[top]
000
FXUS62 KCHS 230542
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
1242 AM EST MON NOV 23 2009
.SYNOPSIS...
AN AREA OF LOW PRESSURE WILL TRACK OFFSHORE ALONG THE SOUTHEAST U.S.
COAST TONIGHT...BEFORE LIFTING NORTHEAST OF THE AREA MONDAY INTO
TUESDAY. MEANWHILE...A HIGH PRESSURE WEDGE WILL REMAIN FIRMLY
ENTRENCHED OVER COASTAL SOUTH CAROLINA AND GEORGIA THROUGH TUESDAY.
ANOTHER AREA OF LOW PRESSURE IS EXPECTED TO MOVE ACROSS THE EASTERN
GULF OF MEXICO ON WEDNESDAY THEN ACROSS THE SOUTHWEST ATLANTIC ON
THURSDAY. HIGH PRESSURE WILL THEN GRADUALLY BUILD OVER THE REGION
FROM THE WEST THROUGH NEXT WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
SURFACE ANALYSIS LATE SUNDAY EVENING SHOWS THE REMNANTS OF LOW
PRESSURE NEAR THE COAST OF THE FL BIG BEND...WITH A SECOND LOW
BEGINNING TO FORM OFF THE NE FL COAST. THIS SECOND LOW WILL BECOME
THE MAIN LOW AS IT DEEPENS AROUND A MILLIBAR TONIGHT.
MEANWHILE...THE HIGH PRESSURE WEDGE WILL REMAIN ANCHORED IN
PLACE...ONLY REINFORCED ON THE WEST AND NW SIDE OF THE DEVELOPING
ATLANTIC LOW. ALOFT WE HAVE SEEN ONE SHORT WAVE THAT CAUSED SOME
OF THE EARLIER RAINS MOVE INTO THE ATLANTIC...BUT ANOTHER WEAK
SHORT WAVE IS SEEN ON WATER VAPOR MOVING THROUGH SOUTHERN GA.
ABUNDANT LOW LEVEL MOISTURE WILL REMAIN IN PLACE TONIGHT...TRAPPED
BENEATH THE NOCTURNAL INVERSION...AND THAT ALONG WITH THE SHORT
WAVE AND WEAK ISENTROPIC LIFT WILL STILL PRODUCE OCCASIONAL LIGHT
RAIN...DRIZZLE AND FOG. BUT THE STEADY RAINS HAVE ENDED...AND WE
WILL ADJUST POPS DOWN TO NO MORE THAN 30-50 PERCENT.
GIVEN ALL THE RAINS FROM EARLIER...DOPPLER RADAR SHOWS 1/4 TO 1/2
INCH AMOUNTS IN MOST LOCATIONS THERE IS CERTAINLY THE POTENTIAL
FOR DENSE FOG. BUT 1000 MB GEOSTROPHIC WINDS DROP NO LESS THAN
10-15 KT...WHICH WOULD PREVENT ITS FORMATION. HOWEVER...WITH
WIDESPREAD STRATUS LOWERING THROUGH THE NIGHT...IT MAY BECOME MORE
SURFACE BASED AND LEAD TO A CONCERN FOR DENSE FOG. WE WILL
CONTINUE TO MONITOR.
TEMPS WILL MOVE LITTLE THROUGH THE NIGHT...EVEN RISE A DEGREE OR
TWO...WITH MIN TEMPS MOSTLY IN THE UPPER 40S AND LOWER 50S.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM TUESDAY/...
NORTHERLY FLOW WILL PERSIST INTO MONDAY BEHIND A DEPARTING SURFACE
LOW WHILE A WEAK COASTAL TROUGH REMAINS OFF THE COAST. WITH HIGH
PRESSURE CONTINUING TO RIDGE IN FROM THE NORTH...WEAK ISENTROPIC
ASCENT WILL MAINTAIN CLOUDY SKIES IN MOST AREAS WITH AREAS OF
DRIZZLE POSSIBLE. THE BRUNT OF THE HEAVIER RAINFALL SHOULD BE WELL
NE OF THE AREA BY MID-MORNING. COLD ADVECTION WILL MAINTAIN BELOW-
NORMAL TEMPERATURES /MID TO UPPER 50S/.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
LOW PRESSURE WILL CONTINUE TO TRACK NORTH-NORTHEAST OFF THE
MID-ATLANTIC AND NEW ENGLAND COASTS MONDAY NIGHT INTO TUESDAY. AS
THIS OCCURS...THE RESULTING NORTHERLY FLOW OVER THE REGION WILL ACT
TO REINFORCE THE EXISTING WEDGE...WHICH SHOULD CONTINUE TO EXTEND
SOUTHWARD TO JUST NORTH OF THE ALTAMAHA RIVER. MODEL TIME/HEIGHT
CROSS SECTIONS CONTINUE TO DEPICT ABUNDANT MOISTURE WITHIN THE
BOUNDARY LAYER TRAPPED BENEATH THE LOW LEVEL INVERSION...WHICH
SHOULD BE ENOUGH TO SUPPORT CLOUDY SKIES AND AREAS OF DRIZZLE INTO
TUESDAY MORNING. IN ADDITION...LOW CEILINGS MAY DROP TO THE SURFACE
MONDAY NIGHT INTO TUESDAY MORNING IN A WEAK LOW LEVEL WIND REGIME...
RESULTING IN AREAS OF FOG WHICH COULD BECOME DENSE IN SOME
LOCATIONS. THIS IS ALSO SUPPORTED BY THE SHORT RANGE ENSEMBLE
FORECAST /SREF/ WHICH HAS RATHER HIGH PROBABILITIES OF LOW
VISIBILITIES ACROSS THE AREA. AS FOR TEMPERATURES...CONTINUE TO
FORECAST HIGHS WELL BELOW GUIDANCE ON TUESDAY AS MODELS LIKELY DO
NOT HAVE A GOOD HANDLE OF THE STRENGTH OF THE WEDGE.
SOME UNCERTAINTY DEVELOPS DURING THE MID-WEEK PERIOD AS MODELS HAVE
BEGUN TO TREND TOWARD THE SOLUTION OF LOW PRESSURE TRACKING ACROSS
THE EASTERN GULF OF MEXICO ON WEDNESDAY...THEN SHIFTING/REDEVELOPING
OVER THE SOUTHWEST ATLANTIC ON THURSDAY. ACCOUNTING FOR THE LATEST
MODEL TRENDS...THE FORECAST REFLECTS A SLIGHT CHANCE OF SHOWERS
ACROSS NORTH COASTAL GEORGIA ON WEDNESDAY...ACROSS ALL COASTAL AREAS
WEDNESDAY NIGHT...THEN SHIFTING NORTH AND EAST OF THE AREA FOR
THANKSGIVING DAY. IF THE MODELS CONTINUE THE TREND IN THIS
DIRECTION...THEN RAIN CHANCES MAY NEED TO BE INCREASED AND/OR
EXPANDED ACROSS MORE OF THE FORECAST AREA.
MEDIUM RANGE GUIDANCE IS IN GOOD AGREEMENT DEPICTING A BROAD UPPER
LEVEL TROUGH SHIFTING OVER THE EASTERN U.S. FRIDAY INTO
SATURDAY...AS STRONG HIGH PRESSURE AT THE SURFACE GRADUALLY BUILDS
FROM THE WEST. THIS WILL RESULT IN DRY CONDITIONS...HOWEVER ROUNDS
OF STRONG COLD AIR ADVECTION WILL DEVELOP AS REINFORCING COLD FRONTS
SHIFT THROUGH AT THE SURFACE. THIS WILL LEAD TO MUCH BELOW NORMAL
TEMPERATURES. THERE MAY EVEN BE SOME FROST/FREEZE CONCERNS
INLAND...WITH THE COOLEST TEMPERATURES EXPECTED FRIDAY NIGHT.
THE SURFACE HIGH WILL SETTLE OVER THE REGION ON SUNDAY WITH WEAK
RIDGING BUILDING ALOFT. THIS WILL ALLOW FOR SLOWLY MODERATING
TEMPERATURES BUT WILL ALSO KEEP DRY CONDITIONS IN PLACE.
&&
.AVIATION /06Z MONDAY THROUGH FRIDAY/...
CONSIDERABLE MOISTURE WILL REMAIN IN PLACE WITH THE HIGH PRES
WEDGE TO PERSIST TODAY. WE LOOK FOR IFR CONDITIONS TO PREVAIL AT
KCHS AND KSAV OVERNIGHT THROUGH EARLY AFTERNOON WITH OCCASIONAL
DRIZZLE AND LIGHT FOG POSSIBLY REDUCING VSBY TO IFR AT KSAV INTO
MID MORNING. INVERSION SHOULD LIFT ENOUGH THIS AFTERNOON FOR SOME
IMPROVEMENT BACK TO MVFR. A COUPLE OF MODELS SUCH AS THE SREF AND
WRF HINT THAT IFR CIGS MAY REMAIN STUBBORN AT KSAV THROUGHOUT THE
AFTERNOON. FORECAST SOUNDINGS SHOW IFR CIGS WILL REDEVELOP AFTER
SUNSET AT BOTH TERMINALS. MVFR VSBYS MAY DEVELOP NOT LONG AFTER
DUSK THIS EVENING.
EXTENDED AVIATION OUTLOOK...IFR/MVFR LIKELY THROUGH WED. VFR CONDITIONS
SHOULD BECOME PREVALENT THU THROUGH FRI.
&&
.MARINE...
THE PINCHING OF THE PRESSURE GRADIENT WILL RELAX THROUGH THE NIGHT
AS WEAK LOW PRESSURE BEGINS DEVELOPING OVER THE NE FL OR SE GA
COASTS BY DAYBREAK. THIS ALLOWS FOR A GRADUAL DECREASE IN WINDS
ACROSS THE MARINE AREA...MOST NOTICEABLE AT FIRST ACROSS THE GA
WATERS WHERE THE LOW BEGINS TO FORM. HOWEVER...GIVEN THE HIGH
WINDS FROM EARLIER TODAY...THE SEAS ARE STILL ELEVATED AND WE WILL
EXTEND THE SCA THROUGH 5 AM FOR ALL WATERS 0-20 NM OFF THE COAST.
FOR THE CHARLESTON HARBOR IT LOOKS LIKE THE LOW LEVEL MIXING WILL
NOT SUPPORT ANYTHING HIGHER THAN 15-20 KT TONIGHT...SO WE HAVE
DROPPED THE SCA. ACROSS THE OUTER GA WATERS...ALTHOUGH WINDS ARE
DROPPING WITH SOME BAGGINESS TO THE PRESSURE PATTERN...SEAS ARE
STILL AS HIGH AS 7 FT AND WILL TAKE LONGER TO COME DOWN. THUS SCA
WILL CONTINUE ACROSS AMZ374 TONIGHT.
MOST OF THE CONVECTION TONIGHT WILL OCCUR OVER AND NEAR THE GULF
STREAM...BUT PATCHY RAINS AND DRIZZLE WILL DEVELOP AFTER MIDNIGHT
AND THERE WILL ALSO BE A SLIGHT REDUCTION IN VSBYS DUE TO THESE
CONDITIONS IN THE CHARLESTON HARBOR...WHERE WE HAVE CARRIED VSBYS
LESS THAN 3NM AT TIMES.
RAPIDLY IMPROVING CONDITIONS WILL OCCUR ON MONDAY AS FLOW BECOMES
OFFSHORE AND GRADIENT SIGNIFICANTLY WEAKENS...AND ANY SCA
CONDITIONS ACROSS THE OUTER GA WATERS WILL END BY AFTERNOON.
MONDAY NIGHT THROUGH FRIDAY...A WEDGE OF HIGH PRESSURE INLAND WILL
KEEP A NORTHERLY FLOW IN PLACE OVER THE COASTAL WATERS THROUGH
WEDNESDAY NIGHT WITH WINDS LESS THAN 15 KT. A COLD FRONT WILL SHIFT
OFFSHORE THURSDAY...WITH STRONG COLD AIR ADVECTION DEVELOPING IN ITS
WAKE. THIS COULD RESULT IN THE DEVELOPMENT OF SMALL CRAFT ADVISORY
CONDITIONS...ESPECIALLY OVER THE OUTER GEORGIA WATERS...BY LATE IN
THE WORK WEEK.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 5 AM EST EARLY THIS MORNING FOR
AMZ350-352-354.
SMALL CRAFT ADVISORY UNTIL 11 AM EST THIS MORNING FOR AMZ374.
&&
$$
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000
FXUS62 KCAE 230535
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
1235 AM EST MON NOV 23 2009
.SYNOPSIS...
LOW PRESSURE ALONG THE GULF COAST WILL MOVE SLOWLY NORTHEAST
ACROSS THE FLORIDA PANHANDLE THIS EVENING THEN REFORM OFF THE GA
COAST LATE TONIGHT. HIGH PRESSURE WILL CONTINUE TO WEDGE INTO THE
CAROLINAS FROM THE NORTH THROUGH TUESDAY. A BRIEF RETURN TO MILD
TEMPERATURES IS EXPECTED WEDNESDAY AND THURSDAY AHEAD OF A COLD
FRONT. DRY AND COOL HIGH PRESSURE WILL BUILD IN NEXT WEEKEND.
&&
.NEAR TERM /OVERNIGHT/...
REGIONAL RADARS SHOW RAIN SHIELD DECREASING SOME ACROSS THE
FORECAST AREA THIS EVENING AS MID AND UPPER LEVEL DRYING TRIES TO
TAKE HOLD PER WATER VAPOR IMAGES. SATELLITE ALSO STILL SEEMS TO
INDICATE ANOTHER SHORT WAVE MOVING THROUGH SOUTH-CENTRAL
GEORGIA...WHICH WILL MOVE THROUGH THE CWA OVERNIGHT. LOW LEVEL
WEDGE FLOW REMAINS AT THE SURFACE. WITH RIPPLES STILL MOVING
NORTHWARD AND OVER THE WEDGE...EXPECT SOME SHOWER ACTIVITY TO
REMAIN OVERNIGHT. HAVE ADJUSTED GRID WORDING SLIGHTLY TO ADD
OCCASIONAL RAIN/DRIZZLE TO THE CATEGORICAL POPS AREAS. OTHER THAN
THAT...GRIDS IN GOOD SHAPE AND VERY LITTLE OTHER CHANGES WERE
MADE. TEMPS TO REMAIN NEARLY STEADY REMAINDER OF THE NIGHT.
UPDATES ALREADY OUT.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
WEDGE PATTERN CONTINUES WITH SOUTHWEST FLOW ALOFT AND NORTHEAST
WIND AT THE SURFACE. SHALLOW MOISTURE TRAPPED BENEATH A STRONG
INVERSION WILL HOLD CONSIDERABLE CLOUDINESS ACROSS THE AREA MONDAY
THROUGH TUESDAY NIGHT. EXPECT SOME LINGERING LIGHT RAIN AND AREAS
OF DRIZZLE ESPECIALLY MONDAY. WILL UNDERCUT GUIDANCE MAX TEMPS
HIGH TEMPS. HIGHS IN THE 50S AND LOWS IN THE 40S.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
12Z ECMWF AND 12Z GFS ARE IN PRETTY GOOD AGREEMENT WEDNESDAY
THROUGH SUNDAY. A CLOSED LOW CROSSES THE GREAT LAKES REGION
THROUGH WEDNESDAY. A STRONG SHORTWAVE MOVES FROM THE DAKOTAS TO
THE CENTRAL PLAINS TO DEEPEN THE UPPER LOW OVER THE CENTRAL MS
VALLEY AND OHIO VALLEY THROUGH FRIDAY. THE SURFACE LOW OVER THE
GREAT LAKES REGION SLOWLY MOVES NORTHEAST, DRAGGING A COLD FRONT
ACROSS THE SOUTHEASTERN STATES ON THURSDAY. SINCE MOISTURE IS
LIMITED, EXPECT TO SEE SOME CLOUDINESS BUT LITTLE IF ANY RAINFALL.
MORE PLENTIFUL MOISTURE LOOKS TO REMAIN SOUTH AND EAST OF THE
AREA AND ACROSS THE CENTRAL APPALACHIANS. WILL KEEP THE FORECAST
DRY WEDNESDAY AND THURSDAY.
LARGE MID AND UPPER LEVEL LOW PRESSURE OVER THE EASTERN HALF OF
THE COUNTRY MOVES OFF THE COAST SATURDAY. SURFACE HIGH PRESSURE
BUILDING IN FROM THE WEST FOR NEXT WEEKEND, BRINGING A COOL AND
DRY AIR MASS.
&&
.AVIATION /06Z MONDAY THROUGH SATURDAY/...
HIGH PRESSURE OVER THE MID-ATLANTIC STATES AND NEW ENGLAND WILL MOVE
SLOWLY OFFSHORE THROUGH MONDAY. AN AREA OF LOW LOW PRESSURE ALONG
THE GULF OF MEXICO WILL WEAKEN AS IT MOVES NORTHEAST TOWARD THE
REGION. THE BULK OF THE PRECIPITATION WILL GRADUALLY END FROM SW TO
NE OVERNIGHT LEAVING LOW CLOUDS AND DRIZZLE OVER THE AREA WELL AFTER
SUNRISE MONDAY MORNING. ANTICIPATE IFR/LIFR CONDITIONS FOR MUCH OF
THE 24 HOUR TAF PERIOD...WITH SOME BRIEF PERIODS OF MVFR CIGS/VSBYS
MONDAY AFTERNOON IN A FEW LOCATIONS.
EXTENDED AVIATION OUTLOOK...WIDESPREAD MVFR OR IFR CONDITIONS WILL
CONTINUE MONDAY NIGHT AND PERHAPS EVEN INTO TUESDAY AS LOW PRESSURE
MOVES UP THE ATLANTIC COAST AND HIGH PRESSURE CONTINUES TO BUILD IN
FROM THE NORTH.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
000
FXUS62 KCHS 230303
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
1003 PM EST SUN NOV 22 2009
.SYNOPSIS...
AN AREA OF LOW PRESSURE WILL TRACK OFFSHORE ALONG THE SOUTHEAST U.S.
COAST TONIGHT...BEFORE LIFTING NORTHEAST OF THE AREA MONDAY INTO
TUESDAY. MEANWHILE...A HIGH PRESSURE WEDGE WILL REMAIN FIRMLY
ENTRENCHED OVER COASTAL SOUTH CAROLINA AND GEORGIA THROUGH TUESDAY.
ANOTHER AREA OF LOW PRESSURE IS EXPECTED TO MOVE ACROSS THE EASTERN
GULF OF MEXICO ON WEDNESDAY THEN ACROSS THE SOUTHWEST ATLANTIC ON
THURSDAY. HIGH PRESSURE WILL THEN GRADUALLY BUILD OVER THE REGION
FROM THE WEST THROUGH NEXT WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
SURFACE ANALYSIS LATE SUNDAY EVENING SHOWS THE REMNANTS OF LOW
PRESSURE NEAR THE COAST OF THE FL BIG BEND...WITH A SECOND LOW
BEGINNING TO FORM OFF THE NE FL COAST. THIS SECOND LOW WILL BECOME
THE MAIN LOW AS IT DEEPENS AROUND A MILLIBAR TONIGHT.
MEANWHILE...THE HIGH PRESSURE WEDGE WILL REMAIN ANCHORED IN
PLACE...ONLY REINFORCED ON THE WEST AND NW SIDE OF THE DEVELOPING
ATLANTIC LOW. ALOFT WE HAVE SEEN ONE SHORT WAVE THAT CAUSED SOME
OF THE EARLIER RAINS MOVE INTO THE ATLANTIC...BUT ANOTHER WEAK
SHORT WAVE IS SEEN ON WATER VAPOR MOVING THROUGH SOUTHERN GA.
ABUNDANT LOW LEVEL MOISTURE WILL REMAIN IN PLACE TONIGHT...TRAPPED
BENEATH THE NOCTURNAL INVERSION...AND THAT ALONG WITH THE SHORT
WAVE AND WEAK ISENTROPIC LIFT WILL STILL PRODUCE OCCASIONAL LIGHT
RAIN...DRIZZLE AND FOG. BUT THE STEADY RAINS HAVE ENDED...AND WE
WILL ADJUST POPS DOWN TO NO MORE THAN 30-50 PERCENT.
GIVEN ALL THE RAINS FROM EARLIER...DOPPLER RADAR SHOWS 1/4 TO 1/2
INCH AMOUNTS IN MOST LOCATIONS THERE IS CERTAINLY THE POTENTIAL
FOR DENSE FOG. BUT 1000 MB GEOSTROPHIC WINDS DROP NO LESS THAN
10-15 KT...WHICH WOULD PREVENT ITS FORMATION. HOWEVER...WITH
WIDESPREAD STRATUS LOWERING THROUGH THE NIGHT...IT MAY BECOME MORE
SURFACE BASED AND LEAD TO A CONCERN FOR DENSE FOG. WE WILL
CONTINUE TO MONITOR.
TEMPS WILL MOVE LITTLE THROUGH THE NIGHT...EVEN RISE A DEGREE OR
TWO...WITH MIN TEMPS MOSTLY IN THE UPPER 40S AND LOWER 50S.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/...
NORTHERLY FLOW WILL PERSIST INTO MONDAY BEHIND A DEPARTING SURFACE
LOW WHILE A WEAK COASTAL TROUGH REMAINS OFF THE COAST. WITH HIGH
PRESSURE CONTINUING TO RIDGE IN FROM THE NORTH...WEAK ISENTROPIC
ASCENT WILL MAINTAIN CLOUDY SKIES IN MOST AREAS WITH AREAS OF
DRIZZLE POSSIBLE. THE BRUNT OF THE HEAVIER RAINFALL SHOULD BE WELL
NE OF THE AREA BY MID-MORNING. COLD ADVECTION WILL MAINTAIN BELOW-
NORMAL TEMPERATURES /MID TO UPPER 50S/.
&&
.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
LOW PRESSURE WILL CONTINUE TO TRACK NORTH-NORTHEAST OFF THE
MID-ATLANTIC AND NEW ENGLAND COASTS MONDAY NIGHT INTO TUESDAY. AS
THIS OCCURS...THE RESULTING NORTHERLY FLOW OVER THE REGION WILL ACT
TO REINFORCE THE EXISTING WEDGE...WHICH SHOULD CONTINUE TO EXTEND
SOUTHWARD TO JUST NORTH OF THE ALTAMAHA RIVER. MODEL TIME/HEIGHT
CROSS SECTIONS CONTINUE TO DEPICT ABUNDANT MOISTURE WITHIN THE
BOUNDARY LAYER TRAPPED BENEATH THE LOW LEVEL INVERSION...WHICH
SHOULD BE ENOUGH TO SUPPORT CLOUDY SKIES AND AREAS OF DRIZZLE INTO
TUESDAY MORNING. IN ADDITION...LOW CEILINGS MAY DROP TO THE SURFACE
MONDAY NIGHT INTO TUESDAY MORNING IN A WEAK LOW LEVEL WIND REGIME...
RESULTING IN AREAS OF FOG WHICH COULD BECOME DENSE IN SOME
LOCATIONS. THIS IS ALSO SUPPORTED BY THE SHORT RANGE ENSEMBLE
FORECAST /SREF/ WHICH HAS RATHER HIGH PROBABILITIES OF LOW
VISIBILITIES ACROSS THE AREA. AS FOR TEMPERATURES...CONTINUE TO
FORECAST HIGHS WELL BELOW GUIDANCE ON TUESDAY AS MODELS LIKELY DO
NOT HAVE A GOOD HANDLE OF THE STRENGTH OF THE WEDGE.
SOME UNCERTAINTY DEVELOPS DURING THE MID-WEEK PERIOD AS MODELS HAVE
BEGUN TO TREND TOWARD THE SOLUTION OF LOW PRESSURE TRACKING ACROSS
THE EASTERN GULF OF MEXICO ON WEDNESDAY...THEN SHIFTING/REDEVELOPING
OVER THE SOUTHWEST ATLANTIC ON THURSDAY. ACCOUNTING FOR THE LATEST
MODEL TRENDS...THE FORECAST REFLECTS A SLIGHT CHANCE OF SHOWERS
ACROSS NORTH COASTAL GEORGIA ON WEDNESDAY...ACROSS ALL COASTAL AREAS
WEDNESDAY NIGHT...THEN SHIFTING NORTH AND EAST OF THE AREA FOR
THANKSGIVING DAY. IF THE MODELS CONTINUE THE TREND IN THIS
DIRECTION...THEN RAIN CHANCES MAY NEED TO BE INCREASED AND/OR
EXPANDED ACROSS MORE OF THE FORECAST AREA.
MEDIUM RANGE GUIDANCE IS IN GOOD AGREEMENT DEPICTING A BROAD UPPER
LEVEL TROUGH SHIFTING OVER THE EASTERN U.S. FRIDAY INTO
SATURDAY...AS STRONG HIGH PRESSURE AT THE SURFACE GRADUALLY BUILDS
FROM THE WEST. THIS WILL RESULT IN DRY CONDITIONS...HOWEVER ROUNDS
OF STRONG COLD AIR ADVECTION WILL DEVELOP AS REINFORCING COLD FRONTS
SHIFT THROUGH AT THE SURFACE. THIS WILL LEAD TO MUCH BELOW NORMAL
TEMPERATURES. THERE MAY EVEN BE SOME FROST/FREEZE CONCERNS
INLAND...WITH THE COOLEST TEMPERATURES EXPECTED FRIDAY NIGHT.
THE SURFACE HIGH WILL SETTLE OVER THE REGION ON SUNDAY WITH WEAK
RIDGING BUILDING ALOFT. THIS WILL ALLOW FOR SLOWLY MODERATING
TEMPERATURES BUT WILL ALSO KEEP DRY CONDITIONS IN PLACE.
&&
.AVIATION /03Z MONDAY THROUGH FRIDAY/...
CONSIDERABLE MOISTURE WILL REMAIN IN PLACE WITH HIGH PRESSURE
WEDGE TO PERSIST TONIGHT INTO MONDAY...AND WITH A LOWERING OF THE
NOCTURNAL INVERSION WE LOOK FOR IFR CONDITIONS TO PREVAIL AT KCHS
AND KSAV MOST OF THE TIME THROUGH 17Z WITH OCCASIONAL DRIZZLE AND
LIGHT FOG. INVERSION LIFTS ENOUGH MONDAY AFTERNOON FOR SOME
IMPROVEMENT BACK TO MVFR WEATHER THE REST OF THE TAF PERIOD.
WINDS FROM THE EVENING SOUNDING ARE SHOWING 30 KT AT 1K FEET...AND
THUS WE HAVE INCLUDED WIND SHEAR AT KSAV THROUGH 03Z WHERE SURFACE
WINDS WILL BE A LITTLE LESS THAN AT KCHS.
EXTENDED AVIATION OUTLOOK...MVFR OR LOWER CONDITIONS ARE LIKELY
MONDAY INTO TUESDAY. VFR CONDITIONS SHOULD BECOME PREVALENT
WEDNESDAY THROUGH FRIDAY.
&&
.MARINE...
THE PINCHING OF THE PRESSURE GRADIENT WILL RELAX THROUGH THE NIGHT
AS WEAK LOW PRESSURE BEGINS DEVELOPING OVER THE NE FL OR SE GA
COASTS BY DAYBREAK. THIS ALLOWS FOR A GRADUAL DECREASE IN WINDS
ACROSS THE MARINE AREA...MOST NOTICEABLE AT FIRST ACROSS THE GA
WATERS WHERE THE LOW BEGINS TO FORM. HOWEVER...GIVEN THE HIGH
WINDS FROM EARLIER TODAY...THE SEAS ARE STILL ELEVATED AND WE WILL
EXTEND THE SCA THROUGH 5 AM FOR ALL WATERS 0-20 NM OFF THE COAST.
FOR THE CHARLESTON HARBOR IT LOOKS LIKE THE LOW LEVEL MIXING WILL
NOT SUPPORT ANYTHING HIGHER THAN 15-20 KT TONIGHT...SO WE HAVE
DROPPED THE SCA. ACROSS THE OUTER GA WATERS...ALTHOUGH WINDS ARE
DROPPING WITH SOME BAGGINESS TO THE PRESSURE PATTERN...SEAS ARE
STILL AS HIGH AS 7 FT AND WILL TAKE LONGER TO COME DOWN. THUS SCA
WILL CONTINUE ACROSS AMZ374 TONIGHT.
MOST OF THE CONVECTION TONIGHT WILL OCCUR OVER AND NEAR THE GULF
STREAM...BUT PATCHY RAINS AND DRIZZLE WILL DEVELOP AFTER MIDNIGHT
AND THERE WILL ALSO BE A SLIGHT REDUCTION IN VSBYS DUE TO THESE
CONDITIONS IN THE CHARLESTON HARBOR...WHERE WE HAVE CARRIED VSBYS
LESS THAN 3NM AT TIMES.
RAPIDLY IMPROVING CONDITIONS WILL OCCUR ON MONDAY AS FLOW BECOMES
OFFSHORE AND GRADIENT SIGNIFICANTLY WEAKENS...AND ANY SCA
CONDITIONS ACROSS THE OUTER GA WATERS WILL END BY AFTERNOON.
MONDAY NIGHT THROUGH FRIDAY...A WEDGE OF HIGH PRESSURE INLAND WILL
KEEP A NORTHERLY FLOW IN PLACE OVER THE COASTAL WATERS THROUGH
WEDNESDAY NIGHT WITH WINDS LESS THAN 15 KT. A COLD FRONT WILL SHIFT
OFFSHORE THURSDAY...WITH STRONG COLD AIR ADVECTION DEVELOPING IN ITS
WAKE. THIS COULD RESULT IN THE DEVELOPMENT OF SMALL CRAFT ADVISORY
CONDITIONS...ESPECIALLY OVER THE OUTER GEORGIA WATERS...BY LATE IN
THE WORK WEEK.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 5 AM EST MONDAY FOR AMZ350-352-354.
SMALL CRAFT ADVISORY UNTIL 11 AM EST MONDAY FOR AMZ374.
&&
$$
33
[top]
000
FXUS62 KGSP 230238
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
938 PM EST SUN NOV 22 2009
.SYNOPSIS...
A COOL AND MOIST WEDGE OF HIGH PRESSURE WILL LINGER ATOP THE REGION
THROUGH AT LEAST MONDAY. MILDER AIR WILL TRY TO PUSH BACK INTO THE
AREA TUESDAY AHEAD OF AN APPROACHING COLD FRONT WHICH IS FORECAST TO
MOVE THROUGH ON THURSDAY.
&&
.NEAR TERM /THROUGH MONDAY/...
AT 0215Z...THE CENTER OF A MID LEVEL S/W WAS LOCATED OVER KTYS AND
SLIDING ENE. LATEST RADAR COMPOSITE INDICATED THAT THE MAJORITY OF
THE RAINFALL COVERED FROM THE EAST SLOPES OF THE NC MTNS TO THE
OUTER BANKS. RAINFALL SHOULD CONTINUE TO LIFT NORTH OVER NIGHT AS
THE S/W APPROACHES AND DEPARTS THE CWA. BY LATE TONIGHT...MEASURABLE
-RA COVERAGE WILL DECREASE SIGNIFICANTLY ACROSS THE WESTERN TIER OF
THE CWA...WITH GOOD COVERAGE LINGERING OVER THE I-77 CORRIDOR.
DURING THE PREDAWN HOURS...LIFT AND MOISTURE SHOULD BECOME
LIMITED...YIELDING MAINLY DRIZZLE. I WILL UPDATE THE FORECAST TO
REFLECT THE LATEST TIMING. MINOR CHANGES WERE MADE TO THE
TEMPERATURE...SKY...AND WIND FORECAST.
MAX TEMPS WILL HARDLY BUDGE TOMORROW AS THE CLASSICAL COLD
AIR DAMMING TRANSITIONS INTO MORE OF AN IN SITU EVENT. THE HIGHER
MTN ELEVATIONS ALONG THE TN LINE MAY SEE SOME CLEARING...BUT
EVERYONE ELSE LOOKS TO STAY CLOUDY...DRIZZLY AND FOGGY THROUGH THE
DAY. IN FACT...THE FOG MAY BECOME WORSE DURING THE DAY AS THE COLD
DOME BEGINS TO WEAKEN.
&&
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
AS OF 115 PM SUNDAY...LINGERING LLVL MOISTURE/SFC RIDGING WITHIN
INCREASINGLY WEAK FLOW REGIME EXPECTED TO ALLOW WEDGE CONDITIONS TO
CONTINUE MONDAY NIGHT. FORCING FOR PCPN IS MINIMAL...WITH JUST
SPOTTY LIGHT RAIN/DRIZZLE STILL PSBL. IT IS NOT CONCLUSIVE WHETHER
ENUF MIXING WILL BE SEEN TO PREVENT FOG FORMATION OUTSIDE OF THE
MTN VALLEYS. TUESDAY IS STILL SHAPING UP TO BE A TRICKY FCST AS THE
DEGREE OF OVERALL IMPROVEMENT IN SKY CONDITIONS REMAIN QUESTIONABLE
WITHIN THE WEAKENING WEDGE...GIVING THE LIGHT AND VARIABLE FLOW
WITHIN THE POTENTIAL SCOURING LAYERS. REGIONALLY...THE BIGGEST MODEL
DISCREPANCY SEEMS TO BE THE MET MOS FCST OF LOW OVC ALL DAY AND
MUCH COOLER MAXES...ESPECIALLY ALONG AND EAST OF I-77. AT THIS
JUNCTURE...WILL GIVE AT LEAST PARTIAL PROPS TO THIS SOLUTION...AND
COOL FROM PERSISTENCE A CATEGORY OR SO ACRS THE EASTERN
PIEDMONT...WITH THE LATEST MOS BLEND ELSEWHERE RESULTING IN PERHAPS
A DOWNWARD DEG OR TWO TWEAK TO GOING MAXES.
NOTWITHSTANDING WHATEVER DEGREE OF LOWER CLOUDS WHICH MAY OR MAY NOT
HAVE MIXED OUT TUESDAY AFTERNOON...WHICH WOULD THEN LINGER INTO
TUESDAY NIGHT...SENSIBLE WX EXPECTED TO BE LIMITED TO NOTHING MORE
THAN A SPOTTY LIGHT SHOWER THREAT WITHIN THE WSW FLOW AHEAD OF FAST
MOVING IMPULSE WITHIN SW FLOW ALOFT. EXPECTING TO MAKE LITTLE CHANGE
TO INHERITED PRE-FRONTAL MINS...SVRL CATEGORIES ABOVE CLIMO.
LINGERING SLIGHT SHOWER CHANCES TO CONTINUE WEDNESDAY MORNING
AS AFOREMENTIONED IMPULSE MOVES QUICKLY THRU. OTHERWISE...A FAIR
AND MILDER DAY REMAINS ON TAP.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
AS OF 240 PM SUNDAY...THE MEDIUM RANGE APPEARS TO BE SHAPING UP AS A
PERIOD OF EARLY WINTER WEATHER...ACROSS THE MTNS AT LEAST. THE
FORECAST STUCK FAIRLY CLOSE TO THE HPC SCENARIO...WHICH FAVORS THE
ECMWF MORE THAN THE OTHER OPERATIONAL MODELS. THE FIRST CONCERN IS
THE THANKSGIVING FORECAST. AT THIS TIME...IT APPEARS THAT ANY SRN
STREAM ENERGY WILL TRACK PAST TOO FAR TO THE SOUTH TO AFFECT THE
WESTERN CAROLINAS. THE MODELS HAVE A SURFACE LOW FAR ENOUGH OFF THE
SOUTHEAST COAST WEDNESDAY NIGHT AND THURSDAY TO MISS US. INSTEAD...
THE POTENT UPPER LOW OVER THE MIDWEST WILL SEND A SHORT WAVE DOWN
ACROSS THE TN VALLEY AND SRN APPALACHIANS. FORCING LOOKS GREAT BUT
THE SYSTEM WILL BE MOISTURE STARVED...SO POP WAS LIMITED TO LOW END
CHC AND SLIGHT CHANCE FAVORING NC...AS IS USUALLY THE CASE WITH
SYSTEMS COMING IN FROM THE W OR NW. THE FRONT SHOULD MOVE THROUGH
LATE IN THE DAY AND WILL USHER IN MUCH COLDER AIR.
WITH THAT...THE STAGE SHOULD BE SET FOR POTENTIALLY THE FIRST REAL
NW FLOW SNOW EVENT OF THE SEASON. PARTIAL THICKNESS VALUES DROP AND
850MB TEMPS DIVE BELOW ZERO IN THE EVENING AS MOISTURE IS PUSHED UP
THE TN SIDE OF THE MTNS. SHOWERS SHOULD BREAK OUT IN THE UPSLOPE
AREAS IN THE EVENING AND WILL CHANGE OVER TO SNOW SHOWERS BY LATE
EVENING. ONCE ESTABLISHED...PRODUCTION OF PRECIP IN THE NW FLOW
SHOULD CONTINUE INTO FRIDAY EVENING. FRIDAY IS AN INTERESTING DAY.
HAVE CUT HIGH TEMPS OVER THE MTNS BASED ON THE CLOUDS AND SHOWER
ACTIVITY BUT NOT ENOUGH TO KEEP SHOWERS IN A SOLID FORM. I SUSPECT
THAT MY HIGH TEMP IS OPTIMISTICALLY HIGH...IN WHICH CASE IT WOULD
FOLLOW THAT SHOWERS WOULD REMAIN IN THE FORM OF SNOW OR RAIN/SNOW
MIXED FOR A LONGER PERIOD OF THE DAY. AT ANY RATE...SHOWERS SHOULD
CHANGE BACK TO SNOW IN THE EVENING BEFORE ENDING LATE FRIDAY NIGHT.
SATURDAY AND SUNDAY SHOULD SEE TEMPS GRADUALLY REBOUND TO
CLIMATOLOGICAL VALUES WITH HIGH PRESSURE BUILDING IN FROM THE WEST.
HAVE KEPT THE NEXT SYSTEM AT BAY TO THE WEST ON SUNDAY FOR THE TIME
BEING.
&&
.AVIATION /03Z MONDAY THROUGH FRIDAY/...
AT KCLT...UPSTREAM OBS TREND AND FORECAST SOUNDINGS INDICATE THAT
MVFR CONDITIONS WILL DEVELOP OVER THE TERMINAL BETWEEN 00-03Z. MOS
GUIDANCE AND FORECAST SOUNDINGS INDICATE THAT IFR CEILINGS ARE IN
THE OFFING AFTER MIDNIGHT. BASED ON MODEL TIMING OF THE TMB...I WILL
FORECAST IFR CEILINGS ARRIVING AROUND 08Z. LLVL CONDITIONS SHOULD
REMAIN NEARLY SATURATED THROUGH THE REST OF THE TAF PERIOD.
HOWEVER...RAINFALL RATES WILL DECREASE SIGNIFICANTLY AFTER SUNRISE
WITH LOSS OF DEEP MOISTURE AND LIFT. SHALLOW MOISTURE AND LIFT WILL
LIKELY SUPPORT -DZ AND IFR CEILINGS FROM MID DAY MON THROUGH THE
REST OF THE TAF PERIOD.
WINDS WILL REMAIN NORTHEAST FROM 020-040 DEGREES BETWEEN 6-10 KTS
THROUGH THE TAF PERIOD. MARGINAL LLWS COULD DEVELOP BETWEEN 03-09Z.
I WILL NOT MENTION IN THE TAFS AT THIS TIME...BUT I WILL CONTINUE TO
MONITOR VWP FROM THE TCLT FOR WIND TRENDS.
ELSEWHERE...AT 2330Z...A MODERATE TO HEAVY PATCH OF -RA WAS LOCATED
NEAR KAVL. THIS AREA OF RA WILL CONTINUE TO LIFT NORTHWARD...PASSING
CLOSE TO KHKY BETWEEN 01-02Z. THE REST OF THE NIGHT...AREAS OF -RA
SHOULD CONTINUE TO MOVE ACROSS THE WESTERN CAROLINAS...WITH RAINFALL
RATES DECREASING SIGNIFICANTLY DURING THE PRE DAWN HOURS. LIGHT DZ
WILL LIKELY DEVELOP BETWEEN MID MORNING AND NOON MONDAY AND REMAIN
THE REST OF THE DAY.
CEILINGS WILL FAVOR IFR DURING THE NIGHT AND MAY IMPROVE SLOWLY
AFTER SUNRISE MONDAY. DURING THE AFTERNOON...MVFR CONDITIONS MAY
SWEEP ACROSS THE WESTERN CAROLINAS LATE TOMORROW AFTERNOON.
OTHERWISE...LIGHT NORTHEAST WINDS WILL PERSIST...EXCEPT NORTH WINDS
AT KAVL.
OUTLOOK...WIDESPREAD IFR CONDITIONS ARE EXPECTED TO CONTINUE MONDAY
NIGHT. MODEL GUIDANCE SHOWS IMPROVEMENT TUESDAY BUT MOST LIKELY AT
BEST MVFR SHOULD BE EXPECTED UNTIL WEDNESDAY. A COLD FRONT WILL
BRING WINDY CONDITIONS ON THURSDAY AND A FEW RESTRICTIONS IN SHOWERS
IN THE MOUNTAINS.
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...CSH
NEAR TERM...NED/MCAVOY
SHORT TERM...CSH
LONG TERM...PM
AVIATION...NED
000
FXUS62 KCAE 230216
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
916 PM EST SUN NOV 22 2009
.SYNOPSIS...
LOW PRESSURE ALONG THE GULF COAST WILL MOVE SLOWLY NORTHEAST
ACROSS THE FLORIDA PANHANDLE THIS EVENING THEN REFORM OFF THE GA
COAST LATE TONIGHT. HIGH PRESSURE WILL CONTINUE TO WEDGE INTO THE
CAROLINAS FROM THE NORTH THROUGH TUESDAY. A BRIEF RETURN TO MILD
TEMPERATURES IS EXPECTED WEDNESDAY AND THURSDAY AHEAD OF A COLD
FRONT. DRY AND COOL HIGH PRESSURE WILL BUILD IN NEXT WEEKEND.
&&
.NEAR TERM /OVERNIGHT/...
REGIONAL RADARS SHOW RAIN SHIELD DECREASING SOME ACROSS THE
FORECAST AREA THIS EVENING AS MID AND UPPER LEVEL DRYING TRIES TO
TAKE HOLD PER WATER VAPOR IMAGES. SATELLITE ALSO STILL SEEMS TO
INDICATE ANOTHER SHORT WAVE MOVING THROUGH SOUTH-CENTRAL
GEORGIA...WHICH WILL MOVE THROUGH THE CWA OVERNIGHT. LOW LEVEL
WEDGE FLOW REMAINS AT THE SURFACE. WITH RIPPLES STILL MOVING
NORTHWARD AND OVER THE WEDGE...EXPECT SOME SHOWER ACTIVITY TO
REMAIN OVERNIGHT. HAVE ADJUSTED GRID WORDING SLIGHTLY TO ADD
OCCASIONAL RAIN/DRIZZLE TO THE CATEGORICAL POPS AREAS. OTHER THAN
THAT...GRIDS IN GOOD SHAPE AND VERY LITTLE OTHER CHANGES WERE
MADE. TEMPS TO REMAIN NEARLY STEADY REMAINDER OF THE NIGHT.
UPDATES ALREADY OUT.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
WEDGE PATTERN CONTINUES WITH SOUTHWEST FLOW ALOFT AND NORTHEAST
WIND AT THE SURFACE. SHALLOW MOISTURE TRAPPED BENEATH A STRONG
INVERSION WILL HOLD CONSIDERABLE CLOUDINESS ACROSS THE AREA MONDAY
THROUGH TUESDAY NIGHT. EXPECT SOME LINGERING LIGHT RAIN AND AREAS
OF DRIZZLE ESPECIALLY MONDAY. WILL UNDERCUT GUIDANCE MAX TEMPS
HIGH TEMPS. HIGHS IN THE 50S AND LOWS IN THE 40S.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
12Z ECMWF AND 12Z GFS ARE IN PRETTY GOOD AGREEMENT WEDNESDAY
THROUGH SUNDAY. A CLOSED LOW CROSSES THE GREAT LAKES REGION
THROUGH WEDNESDAY. A STRONG SHORTWAVE MOVES FROM THE DAKOTAS TO
THE CENTRAL PLAINS TO DEEPEN THE UPPER LOW OVER THE CENTRAL MS
VALLEY AND OHIO VALLEY THROUGH FRIDAY. THE SURFACE LOW OVER THE
GREAT LAKES REGION SLOWLY MOVES NORTHEAST, DRAGGING A COLD FRONT
ACROSS THE SOUTHEASTERN STATES ON THURSDAY. SINCE MOISTURE IS
LIMITED, EXPECT TO SEE SOME CLOUDINESS BUT LITTLE IF ANY RAINFALL.
MORE PLENTIFUL MOISTURE LOOKS TO REMAIN SOUTH AND EAST OF THE
AREA AND ACROSS THE CENTRAL APPALACHIANS. WILL KEEP THE FORECAST
DRY WEDNESDAY AND THURSDAY.
LARGE MID AND UPPER LEVEL LOW PRESSURE OVER THE EASTERN HALF OF
THE COUNTRY MOVES OFF THE COAST SATURDAY. SURFACE HIGH PRESSURE
BUILDING IN FROM THE WEST FOR NEXT WEEKEND, BRINGING A COOL AND
DRY AIR MASS.
&&
.AVIATION /02Z MONDAY THROUGH FRIDAY/...
HIGH PRESSURE OVER THE MID-ATLANTIC STATES AND NEW ENGLAND WILL MOVE
SLOWLY OFFSHORE THROUGH MONDAY. AN AREA OF LOW LOW PRESSURE ALONG
THE GULF OF MEXICO WILL WEAKEN AS IT MOVES NORTHEAST TOWARD THE
REGION. PRECIPITATION WILL GRADUALLY END FROM SW TO NE OVERNIGHT
LEAVING LOW CLOUDS AND DRIZZLE OVER THE AREA WELL AFTER SUNRISE
MONDAY MORNING. ANTICIPATE IFR/LIFR CONDITIONS FOR MUCH OF THE 24
HOUR TAF PERIOD...WITH SOME BRIEF PERIODS OF MVFR CIGS/VSBYS MONDAY
AFTERNOON IN A FEW LOCATIONS.
EXTENDED AVIATION OUTLOOK...WIDESPREAD MVFR OR IFR CONDITIONS WILL
CONTINUE MONDAY NIGHT AND PERHAPS EVEN INTO TUESDAY AS LOW PRESSURE
MOVES UP THE ATLANTIC COAST AND HIGH PRESSURE CONTINUES TO BUILD IN
FROM THE NORTH.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
000
FXUS62 KGSP 230001
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
701 PM EST SUN NOV 22 2009
.SYNOPSIS...
A COOL AND MOIST WEDGE OF HIGH PRESSURE WILL LINGER ATOP THE REGION
THROUGH AT LEAST MONDAY. MILDER AIR WILL TRY TO PUSH BACK INTO THE
AREA TUESDAY AHEAD OF AN APPROACHING COLD FRONT WHICH IS FORECAST TO
MOVE THROUGH ON THURSDAY.
&&
.NEAR TERM /THROUGH MONDAY/...
THE AREA OF STRONG ASCENT...ASSOCIATED WITH MID-LEVEL FRONTOGENESIS
AND A COUPLED UPPER JET...WILL MOVE NORTHEAST OF THE REGION EARLY
THIS EVENING. WHILE THAT WILL BE THE END OF DEEP LAYER
FORCING...THERE REMAINS GOOD LLVL FORCING IN THE FORM OF LLVL WARM
ADVECTION ALONG THE H8 FRONT. THE FRONT CURRENTLY EXTENDS ACROSS THE
MIDLANDS AND N CNTRL GA...BUT IT WILL LIFT NORTHWARD OVERNIGHT. THE
BEST FORCING WILL OCCUR BETWEEN 00 AND 06 UTC...PARTICULARLY EAST OF
THE HIGHER MTN ELEVATIONS. I HAVE CATEGORICAL POPS OVER MOST OF THE
FA FOR THE OVERNIGHT HOURS.
AREAS ALONG THE I-77 CORRIDOR HOLD ON THE WARM ADVECTION THROUGH THE
MORNING HOURS ON MONDAY...AND I/VE KEPT POPS IN THIS AREA HIGH
THROUGH THE FIRST HALF OF THE DAY. THIS IS SUPPORTED BY THE SREF QPF
FIELDS. MAX TEMPS WILL HARDLY BUDGE TOMORROW AS THE CLASSICAL COLD
AIR DAMMING TRANSITIONS INTO MORE OF AN IN SITU EVENT. THE HIGHER
MTN ELEVATIONS ALONG THE TN LINE MAY SEE SOME CLEARING...BUT
EVERYONE ELSE LOOKS TO STAY CLOUDY...DRIZZLY AND FOGGY THROUGH THE
DAY. IN FACT...THE FOG MAY BECOME WORSE DURING THE DAY AS THE COLD
DOME BEGINS TO WEAKEN.
&&
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
AS OF 115 PM SUNDAY...LINGERING LLVL MOISTURE/SFC RIDGING WITHIN
INCREASINGLY WEAK FLOW REGIME EXPECTED TO ALLOW WEDGE CONDITIONS TO
CONTINUE MONDAY NIGHT. FORCING FOR PCPN IS MINIMAL...WITH JUST
SPOTTY LIGHT RAIN/DRIZZLE STILL PSBL. IT IS NOT CONCLUSIVE WHETHER
ENUF MIXING WILL BE SEEN TO PREVENT FOG FORMATION OUTSIDE OF THE
MTN VALLEYS. TUESDAY IS STILL SHAPING UP TO BE A TRICKY FCST AS THE
DEGREE OF OVERALL IMPROVEMENT IN SKY CONDITIONS REMAIN QUESTIONABLE
WITHIN THE WEAKENING WEDGE...GIVING THE LIGHT AND VARIABLE FLOW
WITHIN THE POTENTIAL SCOURING LAYERS. REGIONALLY...THE BIGGEST MODEL
DISCREPANCY SEEMS TO BE THE MET MOS FCST OF LOW OVC ALL DAY AND
MUCH COOLER MAXES...ESPECIALLY ALONG AND EAST OF I-77. AT THIS
JUNCTURE...WILL GIVE AT LEAST PARTIAL PROPS TO THIS SOLUTION...AND
COOL FROM PERSISTENCE A CATEGORY OR SO ACRS THE EASTERN
PIEDMONT...WITH THE LATEST MOS BLEND ELSEWHERE RESULTING IN PERHAPS
A DOWNWARD DEG OR TWO TWEAK TO GOING MAXES.
NOTWITHSTANDING WHATEVER DEGREE OF LOWER CLOUDS WHICH MAY OR MAY NOT
HAVE MIXED OUT TUESDAY AFTERNOON...WHICH WOULD THEN LINGER INTO
TUESDAY NIGHT...SENSIBLE WX EXPECTED TO BE LIMITED TO NOTHING MORE
THAN A SPOTTY LIGHT SHOWER THREAT WITHIN THE WSW FLOW AHEAD OF FAST
MOVING IMPULSE WITHIN SW FLOW ALOFT. EXPECTING TO MAKE LITTLE CHANGE
TO INHERITED PRE-FRONTAL MINS...SVRL CATEGORIES ABOVE CLIMO.
LINGERING SLIGHT SHOWER CHANCES TO CONTINUE WEDNESDAY MORNING
AS AFOREMENTIONED IMPULSE MOVES QUICKLY THRU. OTHERWISE...A FAIR
AND MILDER DAY REMAINS ON TAP.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
AS OF 240 PM SUNDAY...THE MEDIUM RANGE APPEARS TO BE SHAPING UP AS A
PERIOD OF EARLY WINTER WEATHER...ACROSS THE MTNS AT LEAST. THE
FORECAST STUCK FAIRLY CLOSE TO THE HPC SCENARIO...WHICH FAVORS THE
ECMWF MORE THAN THE OTHER OPERATIONAL MODELS. THE FIRST CONCERN IS
THE THANKSGIVING FORECAST. AT THIS TIME...IT APPEARS THAT ANY SRN
STREAM ENERGY WILL TRACK PAST TOO FAR TO THE SOUTH TO AFFECT THE
WESTERN CAROLINAS. THE MODELS HAVE A SURFACE LOW FAR ENOUGH OFF THE
SOUTHEAST COAST WEDNESDAY NIGHT AND THURSDAY TO MISS US. INSTEAD...
THE POTENT UPPER LOW OVER THE MIDWEST WILL SEND A SHORT WAVE DOWN
ACROSS THE TN VALLEY AND SRN APPALACHIANS. FORCING LOOKS GREAT BUT
THE SYSTEM WILL BE MOISTURE STARVED...SO POP WAS LIMITED TO LOW END
CHC AND SLIGHT CHANCE FAVORING NC...AS IS USUALLY THE CASE WITH
SYSTEMS COMING IN FROM THE W OR NW. THE FRONT SHOULD MOVE THROUGH
LATE IN THE DAY AND WILL USHER IN MUCH COLDER AIR.
WITH THAT...THE STAGE SHOULD BE SET FOR POTENTIALLY THE FIRST REAL
NW FLOW SNOW EVENT OF THE SEASON. PARTIAL THICKNESS VALUES DROP AND
850MB TEMPS DIVE BELOW ZERO IN THE EVENING AS MOISTURE IS PUSHED UP
THE TN SIDE OF THE MTNS. SHOWERS SHOULD BREAK OUT IN THE UPSLOPE
AREAS IN THE EVENING AND WILL CHANGE OVER TO SNOW SHOWERS BY LATE
EVENING. ONCE ESTABLISHED...PRODUCTION OF PRECIP IN THE NW FLOW
SHOULD CONTINUE INTO FRIDAY EVENING. FRIDAY IS AN INTERESTING DAY.
HAVE CUT HIGH TEMPS OVER THE MTNS BASED ON THE CLOUDS AND SHOWER
ACTIVITY BUT NOT ENOUGH TO KEEP SHOWERS IN A SOLID FORM. I SUSPECT
THAT MY HIGH TEMP IS OPTIMISTICALLY HIGH...IN WHICH CASE IT WOULD
FOLLOW THAT SHOWERS WOULD REMAIN IN THE FORM OF SNOW OR RAIN/SNOW
MIXED FOR A LONGER PERIOD OF THE DAY. AT ANY RATE...SHOWERS SHOULD
CHANGE BACK TO SNOW IN THE EVENING BEFORE ENDING LATE FRIDAY NIGHT.
SATURDAY AND SUNDAY SHOULD SEE TEMPS GRADUALLY REBOUND TO
CLIMATOLOGICAL VALUES WITH HIGH PRESSURE BUILDING IN FROM THE WEST.
HAVE KEPT THE NEXT SYSTEM AT BAY TO THE WEST ON SUNDAY FOR THE TIME
BEING.
&&
.AVIATION /00Z MONDAY THROUGH FRIDAY/...
AT KCLT...UPSTREAM OBS TREND AND FORECAST SOUNDINGS INDICATE THAT
MVFR CONDITIONS WILL DEVELOP OVER THE TERMINAL BETWEEN 00-03Z. MOS
GUIDANCE AND FORECAST SOUNDINGS INDICATE THAT IFR CEILINGS ARE IN
THE OFFING AFTER MIDNIGHT. BASED ON MODEL TIMING OF THE TMB...I WILL
FORECAST IFR CEILINGS ARRIVING AROUND 08Z. LLVL CONDITIONS SHOULD
REMAIN NEARLY SATURATED THROUGH THE REST OF THE TAF PERIOD.
HOWEVER...RAINFALL RATES WILL DECREASE SIGNIFICANTLY AFTER SUNRISE
WITH LOSS OF DEEP MOISTURE AND LIFT. SHALLOW MOISTURE AND LIFT WILL
LIKELY SUPPORT -DZ AND IFR CEILINGS FROM MID DAY MON THROUGH THE
REST OF THE TAF PERIOD.
WINDS WILL REMAIN NORTHEAST FROM 020-040 DEGREES BETWEEN 6-10 KTS
THROUGH THE TAF PERIOD. MARGINAL LLWS COULD DEVELOP BETWEEN 03-09Z.
I WILL NOT MENTION IN THE TAFS AT THIS TIME...BUT I WILL CONTINUE TO
MONITOR VWP FROM THE TCLT FOR WIND TRENDS.
ELSEWHERE...AT 2330Z...A MODERATE TO HEAVY PATCH OF -RA WAS LOCATED
NEAR KAVL. THIS AREA OF RA WILL CONTINUE TO LIFT NORTHWARD...PASSING
CLOSE TO KHKY BETWEEN 01-02Z. THE REST OF THE NIGHT...AREAS OF -RA
SHOULD CONTINUE TO MOVE ACROSS THE WESTERN CAROLINAS...WITH RAINFALL
RATES DECREASING SIGNIFICANTLY DURING THE PRE DAWN HOURS. LIGHT DZ
WILL LIKELY DEVELOP BETWEEN MID MORNING AND NOON MONDAY AND REMAIN
THE REST OF THE DAY.
CEILINGS WILL FAVOR IFR DURING THE NIGHT AND MAY IMPROVE SLOWLY
AFTER SUNRISE MONDAY. DURING THE AFTERNOON...MVFR CONDITIONS MAY
SWEEP ACROSS THE WESTERN CAROLINAS LATE TOMORROW AFTERNOON.
OTHERWISE...LIGHT NORTHEAST WINDS WILL PERSIST...EXCEPT NORTH WINDS
AT KAVL.
OUTLOOK...WIDESPREAD IFR CONDITIONS ARE EXPECTED TO CONTINUE MONDAY
NIGHT. MODEL GUIDANCE SHOWS IMPROVEMENT TUESDAY BUT MOST LIKELY AT
BEST MVFR SHOULD BE EXPECTED UNTIL WEDNESDAY. A COLD FRONT WILL
BRING WINDY CONDITIONS ON THURSDAY AND A FEW RESTRICTIONS IN SHOWERS
IN THE MOUNTAINS.
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...CSH
NEAR TERM...MCAVOY
SHORT TERM...CSH
LONG TERM...PM
AVIATION...NED
000
FXUS62 KCAE 222329
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
629 PM EST SUN NOV 22 2009
.SYNOPSIS...
LOW PRESSURE ALONG THE GULF COAST WILL MOVE SLOWLY NORTHEAST
ACROSS THE FLORIDA PANHANDLE THIS EVENING THEN REFORM OFF THE GA
COAST LATE TONIGHT. HIGH PRESSURE WILL CONTINUE TO WEDGE INTO THE
CAROLINAS FROM THE NORTH THROUGH TUESDAY. A BRIEF RETURN TO MILD
TEMPERATURES IS EXPECTED WEDNESDAY AND THURSDAY AHEAD OF A COLD
FRONT. DRY AND COOL HIGH PRESSURE WILL BUILD IN NEXT WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
STRONG WARM AIR ADVECTION/ISENTROPIC LIFT OVER THE AREA THIS
AFTERNOON/EVENING MOVES NORTH OVERNIGHT. SHORT WAVE CROSSING AL/GA
LIFTS NORTHEAST ACROSS THE WESTERN CAROLINAS TONIGHT. WATER VAPOR
SHOWING MID/UPPER LEVEL DRY SLOT OVER SRN GA WORKING ITS WAS INTO
WRN SC.
SURFACE LOW IN THE NORTHERN GULF OF MEXICO WILL CONTINUE TO
WEAKEN...TO RE-DEVELOP ALONG AN INVERTED TROUGH OFF THE SOUTHEAST
COAST. WIDESPREAD RAIN THIS AFTERNOON AND EVENING WILL DECREASE IN
COVERAGE TONIGHT. STILL EXPECT LINGERING DRIZZLE AND A CHANCE OF
LIGHT RAIN. NOT A LOT OF CHANGE IN TEMPERATURES OVERNIGHT...LOWS IN THE
MID/UPPER 40S.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
WEDGE PATTERN CONTINUES WITH SOUTHWEST FLOW ALOFT AND NORTHEAST WIND
AT THE SURFACE. SHALLOW MOISTURE TRAPPED BENEATH A STRONG INVERSION
WILL HOLD CONSIDERABLE CLOUDINESS ACROSS THE AREA MONDAY THROUGH
TUESDAY NIGHT. EXPECT SOME LINGERING LIGHT RAIN AND AREAS OF DRIZZLE
ESPECIALLY MONDAY. WILL UNDERCUT GUIDANCE MAX TEMPS HIGH TEMPS.
HIGHS IN THE 50S AND LOWS IN THE 40S.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
12Z ECMWF AND 12Z GFS ARE IN PRETTY GOOD AGREEMENT WEDNESDAY
THROUGH SUNDAY. A CLOSED LOW CROSSES THE GREAT LAKES REGION
THROUGH WEDNESDAY. A STRONG SHORTWAVE MOVES FROM THE DAKOTAS TO
THE CENTRAL PLAINS TO DEEPEN THE UPPER LOW OVER THE CENTRAL MS
VALLEY AND OHIO VALLEY THROUGH FRIDAY. THE SURFACE LOW OVER THE
GREAT LAKES REGION SLOWLY MOVES NORTHEAST, DRAGGING A COLD FRONT
ACROSS THE SOUTHEASTERN STATES ON THURSDAY. SINCE MOISTURE IS
LIMITED, EXPECT TO SEE SOME CLOUDINESS BUT LITTLE IF ANY RAINFALL.
MORE PLENTIFUL MOISTURE LOOKS TO REMAIN SOUTH AND EAST OF THE
AREA AND ACROSS THE CENTRAL APPALACHIANS. WILL KEEP THE FORECAST
DRY WEDNESDAY AND THURSDAY.
LARGE MID AND UPPER LEVEL LOW PRESSURE OVER THE EASTERN HALF OF
THE COUNTRY MOVES OFF THE COAST SATURDAY. SURFACE HIGH PRESSURE
BUILDING IN FROM THE WEST FOR NEXT WEEKEND, BRINGING A COOL AND
DRY AIR MASS.
&&
.AVIATION /00Z MONDAY THROUGH SATURDAY/...
HIGH PRESSURE OVER THE MID-ATLANTIC STATES AND NEW ENGLAND WILL MOVE
SLOWLY OFFSHORE THROUGH MONDAY. AN AREA OF LOW LOW PRESSURE ALONG
THE GULF OF MEXICO WILL WEAKEN AS IT MOVES NORTHEAST TOWARD THE
REGION. PRECIPITATION WILL GRADUALLY END FROM SW TO NE OVERNIGHT
LEAVING LOW CLOUDS AND DRIZZLE OVER THE AREA WELL AFTER SUNRISE
MONDAY MORNING. ANTICIPATE IFR/LIFR CONDITIONS FOR MUCH OF THE 24
HOUR TAF PERIOD...WITH SOME BRIEF PERIODS OF MVFR CIGS/VSBYS MONDAY
AFTERNOON IN A FEW LOCATIONS.
EXTENDED AVIATION OUTLOOK...WIDESPREAD MVFR OR IFR CONDITIONS WILL
CONTINUE MONDAY NIGHT AND PERHAPS EVEN INTO TUESDAY AS LOW PRESSURE
MOVES UP THE ATLANTIC COAST AND HIGH PRESSURE CONTINUES TO BUILD IN
FROM THE NORTH.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
000
FXUS62 KCHS 222329
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
629 PM EST SUN NOV 22 2009
.SYNOPSIS...
AN AREA OF LOW PRESSURE WILL TRACK OFFSHORE ALONG THE SOUTHEAST U.S.
COAST TONIGHT...BEFORE LIFTING NORTHEAST OF THE AREA MONDAY INTO
TUESDAY. MEANWHILE...A HIGH PRESSURE WEDGE WILL REMAIN FIRMLY
ENTRENCHED OVER COASTAL SOUTH CAROLINA AND GEORGIA THROUGH TUESDAY.
ANOTHER AREA OF LOW PRESSURE IS EXPECTED TO MOVE ACROSS THE EASTERN
GULF OF MEXICO ON WEDNESDAY THEN ACROSS THE SOUTHWEST ATLANTIC ON
THURSDAY. HIGH PRESSURE WILL THEN GRADUALLY BUILD OVER THE REGION
FROM THE WEST THROUGH NEXT WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
AN UPPER LOW LIFTING UP THE SPINE OF THE APPALACHIANS WILL SPUR
SURFACE CYCLOGENESIS OFF THE SC COAST TONIGHT. MEANWHILE...RESIDUAL
LOW PRESSURE IN THE EASTERN GULF WILL CONTINUE TO WEAKEN TONIGHT.
A LOBE OF VORTICITY ON THE EASTERN SIDE OF THE SHORTWAVE IS
RESPONSIBLE FOR MUCH OF THE PRECIPITATION CURRENTLY OVERSPREADING
THE AREA. WEAK NVA ON THE BACK SIDE OF THIS FEATURE IS CLEARING
MOST OF THE PRECIPITATION OUT OF OUR SOUTHWESTERN ZONES. SOME
ADDITIONAL ISENTROPIC LIFT ACROSS SOUTHERN SC MAY OCCUR THIS
EVENING AS THE COASTAL TROUGH STRENGTHENS AND MOISTURE STREAMS OFF
THE ATLANTIC. HOWEVER PRECIP SHOULD START TAPERING OFF FROM SW TO
NE OVERNIGHT AS THE MAJORITY OF THE FORCING PUSHES NE OF THE AREA.
PRODIGIOUS CLOUD COVER AND COLD ADVECTION WILL DROP TEMPS INTO THE
UPPER 40S INLAND TO LOWER 50S COASTAL.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/...
NORTHERLY FLOW WILL PERSIST INTO MONDAY BEHIND A DEPARTING SURFACE
LOW WHILE A WEAK COASTAL TROUGH REMAINS OFF THE COAST. WITH HIGH
PRESSURE CONTINUING TO RIDGE IN FROM THE NORTH...WEAK ISENTROPIC
ASCENT WILL MAINTAIN CLOUDY SKIES IN MOST AREAS WITH AREAS OF
DRIZZLE POSSIBLE. THE BRUNT OF THE HEAVIER RAINFALL SHOULD BE WELL
NE OF THE AREA BY MID-MORNING. COLD ADVECTION WILL MAINTAIN BELOW-
NORMAL TEMPERATURES /MID TO UPPER 50S/.
&&
.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
LOW PRESSURE WILL CONTINUE TO TRACK NORTH-NORTHEAST OFF THE
MID-ATLANTIC AND NEW ENGLAND COASTS MONDAY NIGHT INTO TUESDAY. AS
THIS OCCURS...THE RESULTING NORTHERLY FLOW OVER THE REGION WILL ACT
TO REINFORCE THE EXISTING WEDGE...WHICH SHOULD CONTINUE TO EXTEND
SOUTHWARD TO JUST NORTH OF THE ALTAMAHA RIVER. MODEL TIME/HEIGHT
CROSS SECTIONS CONTINUE TO DEPICT ABUNDANT MOISTURE WITHIN THE
BOUNDARY LAYER TRAPPED BENEATH THE LOW LEVEL INVERSION...WHICH
SHOULD BE ENOUGH TO SUPPORT CLOUDY SKIES AND AREAS OF DRIZZLE INTO
TUESDAY MORNING. IN ADDITION...LOW CEILINGS MAY DROP TO THE SURFACE
MONDAY NIGHT INTO TUESDAY MORNING IN A WEAK LOW LEVEL WIND REGIME...
RESULTING IN AREAS OF FOG WHICH COULD BECOME DENSE IN SOME
LOCATIONS. THIS IS ALSO SUPPORTED BY THE SHORT RANGE ENSEMBLE
FORECAST /SREF/ WHICH HAS RATHER HIGH PROBABILITIES OF LOW
VISIBILITIES ACROSS THE AREA. AS FOR TEMPERATURES...CONTINUE TO
FORECAST HIGHS WELL BELOW GUIDANCE ON TUESDAY AS MODELS LIKELY DO
NOT HAVE A GOOD HANDLE OF THE STRENGTH OF THE WEDGE.
SOME UNCERTAINTY DEVELOPS DURING THE MID-WEEK PERIOD AS MODELS HAVE
BEGUN TO TREND TOWARD THE SOLUTION OF LOW PRESSURE TRACKING ACROSS
THE EASTERN GULF OF MEXICO ON WEDNESDAY...THEN SHIFTING/REDEVELOPING
OVER THE SOUTHWEST ATLANTIC ON THURSDAY. ACCOUNTING FOR THE LATEST
MODEL TRENDS...THE FORECAST REFLECTS A SLIGHT CHANCE OF SHOWERS
ACROSS NORTH COASTAL GEORGIA ON WEDNESDAY...ACROSS ALL COASTAL AREAS
WEDNESDAY NIGHT...THEN SHIFTING NORTH AND EAST OF THE AREA FOR
THANKSGIVING DAY. IF THE MODELS CONTINUE THE TREND IN THIS
DIRECTION...THEN RAIN CHANCES MAY NEED TO BE INCREASED AND/OR
EXPANDED ACROSS MORE OF THE FORECAST AREA.
MEDIUM RANGE GUIDANCE IS IN GOOD AGREEMENT DEPICTING A BROAD UPPER
LEVEL TROUGH SHIFTING OVER THE EASTERN U.S. FRIDAY INTO
SATURDAY...AS STRONG HIGH PRESSURE AT THE SURFACE GRADUALLY BUILDS
FROM THE WEST. THIS WILL RESULT IN DRY CONDITIONS...HOWEVER ROUNDS
OF STRONG COLD AIR ADVECTION WILL DEVELOP AS REINFORCING COLD FRONTS
SHIFT THROUGH AT THE SURFACE. THIS WILL LEAD TO MUCH BELOW NORMAL
TEMPERATURES. THERE MAY EVEN BE SOME FROST/FREEZE CONCERNS
INLAND...WITH THE COOLEST TEMPERATURES EXPECTED FRIDAY NIGHT.
THE SURFACE HIGH WILL SETTLE OVER THE REGION ON SUNDAY WITH WEAK
RIDGING BUILDING ALOFT. THIS WILL ALLOW FOR SLOWLY MODERATING
TEMPERATURES BUT WILL ALSO KEEP DRY CONDITIONS IN PLACE.
&&
.AVIATION /00Z MONDAY THROUGH FRIDAY/...
SHORT WAVE MOVING THROUGH SC THIS EVENING WILL GENERATE AN HOUR OR
LESS OF MODERATE RAINS AT KCHS THROUGH 01Z...OTHERWISE THE STEADY
RAINS HAVE ENDED AT BOTH TERMINALS.
CONSIDERABLE MOISTURE WILL REMAIN IN PLACE WITH HIGH PRESSURE
WEDGE TO PERSIST TONIGHT INTO MONDAY...AND WITH A LOWERING OF THE
NOCTURNAL INVERSION WE LOOK FOR IFR CONDITIONS TO PREVAIL AT KCHS
AND KSAV MOST OF THE TIME THROUGH 17Z WITH OCCASIONAL DRIZZLE AND
LIGHT FOG. INVERSION LIFTS ENOUGH MONDAY AFTERNOON FOR SOME
IMPROVEMENT BACK TO MVFR WEATHER THE REST OF THE TAF PERIOD.
WINDS FROM THE EVENING SOUNDING ARE SHOWING 30 KT AT 1K FEET...AND
THUS WE HAVE INCLUDED WIND SHEAR AT KSAV THROUGH 03Z WHERE SURFACE
WINDS WILL BE A LITTLE LESS THAN AT KCHS.
EXTENDED AVIATION OUTLOOK...MVFR OR LOWER CONDITIONS ARE LIKELY
MONDAY INTO TUESDAY. VFR CONDITIONS SHOULD BECOME PREVALENT
WEDNESDAY THROUGH FRIDAY.
&&
.MARINE...
GRADIENT IS EXPECTED TO TIGHTEN THIS EVENING AS THE COASTAL TROUGH
STRENGTHENS OFF OUR COAST. BRIEF NE WIND SURGE WILL PROBABLY TAKE
PLACE BEFORE A CLOSED SURFACE LOW DEVELOPS NE OF THE WATERS AFTER
MIDNIGHT. WILL CONTINUE SMALL CRAFT ADVISORIES FOR ALL NEARSHORE
WATERS AND THE HARBOR THROUGH MIDNIGHT WITH AN ADVISORY RUNNING
THROUGH 11 AM MONDAY FOR THE OFFSHORE GA WATERS FOR 6 FT SEAS.
RAPIDLY IMPROVING CONDITIONS WILL OCCUR ON MONDAY AS FLOW BECOMES
OFFSHORE AND GRADIENT SIGNIFICANTLY WEAKENS.
MONDAY NIGHT THROUGH FRIDAY...A WEDGE OF HIGH PRESSURE INLAND WILL
KEEP A NORTHERLY FLOW IN PLACE OVER THE COASTAL WATERS THROUGH
WEDNESDAY NIGHT WITH WINDS LESS THAN 15 KT. A COLD FRONT WILL SHIFT
OFFSHORE THURSDAY...WITH STRONG COLD AIR ADVECTION DEVELOPING IN ITS
WAKE. THIS COULD RESULT IN THE DEVELOPMENT OF SMALL CRAFT ADVISORY
CONDITIONS...ESPECIALLY OVER THE OUTER GEORGIA WATERS...BY LATE IN
THE WORK WEEK.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR AMZ330-350-
352-354.
SMALL CRAFT ADVISORY UNTIL 11 AM EST MONDAY FOR AMZ374.
&&
$$
33
000
FXUS62 KCAE 222329
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
629 PM EST SUN NOV 22 2009
.SYNOPSIS...
LOW PRESSURE ALONG THE GULF COAST WILL MOVE SLOWLY NORTHEAST
ACROSS THE FLORIDA PANHANDLE THIS EVENING THEN REFORM OFF THE GA
COAST LATE TONIGHT. HIGH PRESSURE WILL CONTINUE TO WEDGE INTO THE
CAROLINAS FROM THE NORTH THROUGH TUESDAY. A BRIEF RETURN TO MILD
TEMPERATURES IS EXPECTED WEDNESDAY AND THURSDAY AHEAD OF A COLD
FRONT. DRY AND COOL HIGH PRESSURE WILL BUILD IN NEXT WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
STRONG WARM AIR ADVECTION/ISENTROPIC LIFT OVER THE AREA THIS
AFTERNOON/EVENING MOVES NORTH OVERNIGHT. SHORT WAVE CROSSING AL/GA
LIFTS NORTHEAST ACROSS THE WESTERN CAROLINAS TONIGHT. WATER VAPOR
SHOWING MID/UPPER LEVEL DRY SLOT OVER SRN GA WORKING ITS WAS INTO
WRN SC.
SURFACE LOW IN THE NORTHERN GULF OF MEXICO WILL CONTINUE TO
WEAKEN...TO RE-DEVELOP ALONG AN INVERTED TROUGH OFF THE SOUTHEAST
COAST. WIDESPREAD RAIN THIS AFTERNOON AND EVENING WILL DECREASE IN
COVERAGE TONIGHT. STILL EXPECT LINGERING DRIZZLE AND A CHANCE OF
LIGHT RAIN. NOT A LOT OF CHANGE IN TEMPERATURES OVERNIGHT...LOWS IN THE
MID/UPPER 40S.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
WEDGE PATTERN CONTINUES WITH SOUTHWEST FLOW ALOFT AND NORTHEAST WIND
AT THE SURFACE. SHALLOW MOISTURE TRAPPED BENEATH A STRONG INVERSION
WILL HOLD CONSIDERABLE CLOUDINESS ACROSS THE AREA MONDAY THROUGH
TUESDAY NIGHT. EXPECT SOME LINGERING LIGHT RAIN AND AREAS OF DRIZZLE
ESPECIALLY MONDAY. WILL UNDERCUT GUIDANCE MAX TEMPS HIGH TEMPS.
HIGHS IN THE 50S AND LOWS IN THE 40S.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
12Z ECMWF AND 12Z GFS ARE IN PRETTY GOOD AGREEMENT WEDNESDAY
THROUGH SUNDAY. A CLOSED LOW CROSSES THE GREAT LAKES REGION
THROUGH WEDNESDAY. A STRONG SHORTWAVE MOVES FROM THE DAKOTAS TO
THE CENTRAL PLAINS TO DEEPEN THE UPPER LOW OVER THE CENTRAL MS
VALLEY AND OHIO VALLEY THROUGH FRIDAY. THE SURFACE LOW OVER THE
GREAT LAKES REGION SLOWLY MOVES NORTHEAST, DRAGGING A COLD FRONT
ACROSS THE SOUTHEASTERN STATES ON THURSDAY. SINCE MOISTURE IS
LIMITED, EXPECT TO SEE SOME CLOUDINESS BUT LITTLE IF ANY RAINFALL.
MORE PLENTIFUL MOISTURE LOOKS TO REMAIN SOUTH AND EAST OF THE
AREA AND ACROSS THE CENTRAL APPALACHIANS. WILL KEEP THE FORECAST
DRY WEDNESDAY AND THURSDAY.
LARGE MID AND UPPER LEVEL LOW PRESSURE OVER THE EASTERN HALF OF
THE COUNTRY MOVES OFF THE COAST SATURDAY. SURFACE HIGH PRESSURE
BUILDING IN FROM THE WEST FOR NEXT WEEKEND, BRINGING A COOL AND
DRY AIR MASS.
&&
.AVIATION /00Z MONDAY THROUGH SATURDAY/...
HIGH PRESSURE OVER THE MID-ATLANTIC STATES AND NEW ENGLAND WILL MOVE
SLOWLY OFFSHORE THROUGH MONDAY. AN AREA OF LOW LOW PRESSURE ALONG
THE GULF OF MEXICO WILL WEAKEN AS IT MOVES NORTHEAST TOWARD THE
REGION. PRECIPITATION WILL GRADUALLY END FROM SW TO NE OVERNIGHT
LEAVING LOW CLOUDS AND DRIZZLE OVER THE AREA WELL AFTER SUNRISE
MONDAY MORNING. ANTICIPATE IFR/LIFR CONDITIONS FOR MUCH OF THE 24
HOUR TAF PERIOD...WITH SOME BRIEF PERIODS OF MVFR CIGS/VSBYS MONDAY
AFTERNOON IN A FEW LOCATIONS.
EXTENDED AVIATION OUTLOOK...WIDESPREAD MVFR OR IFR CONDITIONS WILL
CONTINUE MONDAY NIGHT AND PERHAPS EVEN INTO TUESDAY AS LOW PRESSURE
MOVES UP THE ATLANTIC COAST AND HIGH PRESSURE CONTINUES TO BUILD IN
FROM THE NORTH.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
000
FXUS62 KCHS 222329
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
629 PM EST SUN NOV 22 2009
.SYNOPSIS...
AN AREA OF LOW PRESSURE WILL TRACK OFFSHORE ALONG THE SOUTHEAST U.S.
COAST TONIGHT...BEFORE LIFTING NORTHEAST OF THE AREA MONDAY INTO
TUESDAY. MEANWHILE...A HIGH PRESSURE WEDGE WILL REMAIN FIRMLY
ENTRENCHED OVER COASTAL SOUTH CAROLINA AND GEORGIA THROUGH TUESDAY.
ANOTHER AREA OF LOW PRESSURE IS EXPECTED TO MOVE ACROSS THE EASTERN
GULF OF MEXICO ON WEDNESDAY THEN ACROSS THE SOUTHWEST ATLANTIC ON
THURSDAY. HIGH PRESSURE WILL THEN GRADUALLY BUILD OVER THE REGION
FROM THE WEST THROUGH NEXT WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
AN UPPER LOW LIFTING UP THE SPINE OF THE APPALACHIANS WILL SPUR
SURFACE CYCLOGENESIS OFF THE SC COAST TONIGHT. MEANWHILE...RESIDUAL
LOW PRESSURE IN THE EASTERN GULF WILL CONTINUE TO WEAKEN TONIGHT.
A LOBE OF VORTICITY ON THE EASTERN SIDE OF THE SHORTWAVE IS
RESPONSIBLE FOR MUCH OF THE PRECIPITATION CURRENTLY OVERSPREADING
THE AREA. WEAK NVA ON THE BACK SIDE OF THIS FEATURE IS CLEARING
MOST OF THE PRECIPITATION OUT OF OUR SOUTHWESTERN ZONES. SOME
ADDITIONAL ISENTROPIC LIFT ACROSS SOUTHERN SC MAY OCCUR THIS
EVENING AS THE COASTAL TROUGH STRENGTHENS AND MOISTURE STREAMS OFF
THE ATLANTIC. HOWEVER PRECIP SHOULD START TAPERING OFF FROM SW TO
NE OVERNIGHT AS THE MAJORITY OF THE FORCING PUSHES NE OF THE AREA.
PRODIGIOUS CLOUD COVER AND COLD ADVECTION WILL DROP TEMPS INTO THE
UPPER 40S INLAND TO LOWER 50S COASTAL.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/...
NORTHERLY FLOW WILL PERSIST INTO MONDAY BEHIND A DEPARTING SURFACE
LOW WHILE A WEAK COASTAL TROUGH REMAINS OFF THE COAST. WITH HIGH
PRESSURE CONTINUING TO RIDGE IN FROM THE NORTH...WEAK ISENTROPIC
ASCENT WILL MAINTAIN CLOUDY SKIES IN MOST AREAS WITH AREAS OF
DRIZZLE POSSIBLE. THE BRUNT OF THE HEAVIER RAINFALL SHOULD BE WELL
NE OF THE AREA BY MID-MORNING. COLD ADVECTION WILL MAINTAIN BELOW-
NORMAL TEMPERATURES /MID TO UPPER 50S/.
&&
.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
LOW PRESSURE WILL CONTINUE TO TRACK NORTH-NORTHEAST OFF THE
MID-ATLANTIC AND NEW ENGLAND COASTS MONDAY NIGHT INTO TUESDAY. AS
THIS OCCURS...THE RESULTING NORTHERLY FLOW OVER THE REGION WILL ACT
TO REINFORCE THE EXISTING WEDGE...WHICH SHOULD CONTINUE TO EXTEND
SOUTHWARD TO JUST NORTH OF THE ALTAMAHA RIVER. MODEL TIME/HEIGHT
CROSS SECTIONS CONTINUE TO DEPICT ABUNDANT MOISTURE WITHIN THE
BOUNDARY LAYER TRAPPED BENEATH THE LOW LEVEL INVERSION...WHICH
SHOULD BE ENOUGH TO SUPPORT CLOUDY SKIES AND AREAS OF DRIZZLE INTO
TUESDAY MORNING. IN ADDITION...LOW CEILINGS MAY DROP TO THE SURFACE
MONDAY NIGHT INTO TUESDAY MORNING IN A WEAK LOW LEVEL WIND REGIME...
RESULTING IN AREAS OF FOG WHICH COULD BECOME DENSE IN SOME
LOCATIONS. THIS IS ALSO SUPPORTED BY THE SHORT RANGE ENSEMBLE
FORECAST /SREF/ WHICH HAS RATHER HIGH PROBABILITIES OF LOW
VISIBILITIES ACROSS THE AREA. AS FOR TEMPERATURES...CONTINUE TO
FORECAST HIGHS WELL BELOW GUIDANCE ON TUESDAY AS MODELS LIKELY DO
NOT HAVE A GOOD HANDLE OF THE STRENGTH OF THE WEDGE.
SOME UNCERTAINTY DEVELOPS DURING THE MID-WEEK PERIOD AS MODELS HAVE
BEGUN TO TREND TOWARD THE SOLUTION OF LOW PRESSURE TRACKING ACROSS
THE EASTERN GULF OF MEXICO ON WEDNESDAY...THEN SHIFTING/REDEVELOPING
OVER THE SOUTHWEST ATLANTIC ON THURSDAY. ACCOUNTING FOR THE LATEST
MODEL TRENDS...THE FORECAST REFLECTS A SLIGHT CHANCE OF SHOWERS
ACROSS NORTH COASTAL GEORGIA ON WEDNESDAY...ACROSS ALL COASTAL AREAS
WEDNESDAY NIGHT...THEN SHIFTING NORTH AND EAST OF THE AREA FOR
THANKSGIVING DAY. IF THE MODELS CONTINUE THE TREND IN THIS
DIRECTION...THEN RAIN CHANCES MAY NEED TO BE INCREASED AND/OR
EXPANDED ACROSS MORE OF THE FORECAST AREA.
MEDIUM RANGE GUIDANCE IS IN GOOD AGREEMENT DEPICTING A BROAD UPPER
LEVEL TROUGH SHIFTING OVER THE EASTERN U.S. FRIDAY INTO
SATURDAY...AS STRONG HIGH PRESSURE AT THE SURFACE GRADUALLY BUILDS
FROM THE WEST. THIS WILL RESULT IN DRY CONDITIONS...HOWEVER ROUNDS
OF STRONG COLD AIR ADVECTION WILL DEVELOP AS REINFORCING COLD FRONTS
SHIFT THROUGH AT THE SURFACE. THIS WILL LEAD TO MUCH BELOW NORMAL
TEMPERATURES. THERE MAY EVEN BE SOME FROST/FREEZE CONCERNS
INLAND...WITH THE COOLEST TEMPERATURES EXPECTED FRIDAY NIGHT.
THE SURFACE HIGH WILL SETTLE OVER THE REGION ON SUNDAY WITH WEAK
RIDGING BUILDING ALOFT. THIS WILL ALLOW FOR SLOWLY MODERATING
TEMPERATURES BUT WILL ALSO KEEP DRY CONDITIONS IN PLACE.
&&
.AVIATION /00Z MONDAY THROUGH FRIDAY/...
SHORT WAVE MOVING THROUGH SC THIS EVENING WILL GENERATE AN HOUR OR
LESS OF MODERATE RAINS AT KCHS THROUGH 01Z...OTHERWISE THE STEADY
RAINS HAVE ENDED AT BOTH TERMINALS.
CONSIDERABLE MOISTURE WILL REMAIN IN PLACE WITH HIGH PRESSURE
WEDGE TO PERSIST TONIGHT INTO MONDAY...AND WITH A LOWERING OF THE
NOCTURNAL INVERSION WE LOOK FOR IFR CONDITIONS TO PREVAIL AT KCHS
AND KSAV MOST OF THE TIME THROUGH 17Z WITH OCCASIONAL DRIZZLE AND
LIGHT FOG. INVERSION LIFTS ENOUGH MONDAY AFTERNOON FOR SOME
IMPROVEMENT BACK TO MVFR WEATHER THE REST OF THE TAF PERIOD.
WINDS FROM THE EVENING SOUNDING ARE SHOWING 30 KT AT 1K FEET...AND
THUS WE HAVE INCLUDED WIND SHEAR AT KSAV THROUGH 03Z WHERE SURFACE
WINDS WILL BE A LITTLE LESS THAN AT KCHS.
EXTENDED AVIATION OUTLOOK...MVFR OR LOWER CONDITIONS ARE LIKELY
MONDAY INTO TUESDAY. VFR CONDITIONS SHOULD BECOME PREVALENT
WEDNESDAY THROUGH FRIDAY.
&&
.MARINE...
GRADIENT IS EXPECTED TO TIGHTEN THIS EVENING AS THE COASTAL TROUGH
STRENGTHENS OFF OUR COAST. BRIEF NE WIND SURGE WILL PROBABLY TAKE
PLACE BEFORE A CLOSED SURFACE LOW DEVELOPS NE OF THE WATERS AFTER
MIDNIGHT. WILL CONTINUE SMALL CRAFT ADVISORIES FOR ALL NEARSHORE
WATERS AND THE HARBOR THROUGH MIDNIGHT WITH AN ADVISORY RUNNING
THROUGH 11 AM MONDAY FOR THE OFFSHORE GA WATERS FOR 6 FT SEAS.
RAPIDLY IMPROVING CONDITIONS WILL OCCUR ON MONDAY AS FLOW BECOMES
OFFSHORE AND GRADIENT SIGNIFICANTLY WEAKENS.
MONDAY NIGHT THROUGH FRIDAY...A WEDGE OF HIGH PRESSURE INLAND WILL
KEEP A NORTHERLY FLOW IN PLACE OVER THE COASTAL WATERS THROUGH
WEDNESDAY NIGHT WITH WINDS LESS THAN 15 KT. A COLD FRONT WILL SHIFT
OFFSHORE THURSDAY...WITH STRONG COLD AIR ADVECTION DEVELOPING IN ITS
WAKE. THIS COULD RESULT IN THE DEVELOPMENT OF SMALL CRAFT ADVISORY
CONDITIONS...ESPECIALLY OVER THE OUTER GEORGIA WATERS...BY LATE IN
THE WORK WEEK.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR AMZ330-350-
352-354.
SMALL CRAFT ADVISORY UNTIL 11 AM EST MONDAY FOR AMZ374.
&&
$$
33
000
FXUS62 KCHS 222122
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
422 PM EST SUN NOV 22 2009
.SYNOPSIS...
AN AREA OF LOW PRESSURE WILL TRACK OFFSHORE ALONG THE SOUTHEAST U.S.
COAST TONIGHT...BEFORE LIFTING NORTHEAST OF THE AREA MONDAY INTO
TUESDAY. MEANWHILE...A HIGH PRESSURE WEDGE WILL REMAIN FIRMLY
ENTRENCHED OVER COASTAL SOUTH CAROLINA AND GEORGIA THROUGH TUESDAY.
ANOTHER AREA OF LOW PRESSURE IS EXPECTED TO MOVE ACROSS THE EASTERN
GULF OF MEXICO ON WEDNESDAY THEN ACROSS THE SOUTHWEST ATLANTIC ON
THURSDAY. HIGH PRESSURE WILL THEN GRADUALLY BUILD OVER THE REGION
FROM THE WEST THROUGH NEXT WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
AN UPPER LOW LIFTING UP THE SPINE OF THE APPALACHIANS WILL SPUR
SURFACE CYCLOGENESIS OFF THE SC COAST TONIGHT. MEANWHILE...RESIDUAL
LOW PRESSURE IN THE EASTERN GULF WILL CONTINUE TO WEAKEN TONIGHT.
A LOBE OF VORTICITY ON THE EASTERN SIDE OF THE SHORTWAVE IS
RESPONSIBLE FOR MUCH OF THE PRECIPITATION CURRENTLY OVERSPREADING
THE AREA. WEAK NVA ON THE BACK SIDE OF THIS FEATURE IS CLEARING
MOST OF THE PRECIPITATION OUT OF OUR SOUTHWESTERN ZONES. SOME
ADDITIONAL ISENTROPIC LIFT ACROSS SOUTHERN SC MAY OCCUR THIS
EVENING AS THE COASTAL TROUGH STRENGTHENS AND MOISTURE STREAMS OFF
THE ATLANTIC. HOWEVER PRECIP SHOULD START TAPERING OFF FROM SW TO
NE OVERNIGHT AS THE MAJORITY OF THE FORCING PUSHES NE OF THE AREA.
PRODIGIOUS CLOUD COVER AND COLD ADVECTION WILL DROP TEMPS INTO THE
UPPER 40S INLAND TO LOWER 50S COASTAL.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/...
NORTHERLY FLOW WILL PERSIST INTO MONDAY BEHIND A DEPARTING SURFACE
LOW WHILE A WEAK COASTAL TROUGH REMAINS OFF THE COAST. WITH HIGH
PRESSURE CONTINUING TO RIDGE IN FROM THE NORTH...WEAK ISENTROPIC
ASCENT WILL MAINTAIN CLOUDY SKIES IN MOST AREAS WITH AREAS OF
DRIZZLE POSSIBLE. THE BRUNT OF THE HEAVIER RAINFALL SHOULD BE WELL
NE OF THE AREA BY MID-MORNING. COLD ADVECTION WILL MAINTAIN BELOW-
NORMAL TEMPERATURES /MID TO UPPER 50S/.
&&
.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
LOW PRESSURE WILL CONTINUE TO TRACK NORTH-NORTHEAST OFF THE
MID-ATLANTIC AND NEW ENGLAND COASTS MONDAY NIGHT INTO TUESDAY. AS
THIS OCCURS...THE RESULTING NORTHERLY FLOW OVER THE REGION WILL ACT
TO REINFORCE THE EXISTING WEDGE...WHICH SHOULD CONTINUE TO EXTEND
SOUTHWARD TO JUST NORTH OF THE ALTAMAHA RIVER. MODEL TIME/HEIGHT
CROSS SECTIONS CONTINUE TO DEPICT ABUNDANT MOISTURE WITHIN THE
BOUNDARY LAYER TRAPPED BENEATH THE LOW LEVEL INVERSION...WHICH
SHOULD BE ENOUGH TO SUPPORT CLOUDY SKIES AND AREAS OF DRIZZLE INTO
TUESDAY MORNING. IN ADDITION...LOW CEILINGS MAY DROP TO THE SURFACE
MONDAY NIGHT INTO TUESDAY MORNING IN A WEAK LOW LEVEL WIND REGIME...
RESULTING IN AREAS OF FOG WHICH COULD BECOME DENSE IN SOME
LOCATIONS. THIS IS ALSO SUPPORTED BY THE SHORT RANGE ENSEMBLE
FORECAST /SREF/ WHICH HAS RATHER HIGH PROBABILITIES OF LOW
VISIBILITIES ACROSS THE AREA. AS FOR TEMPERATURES...CONTINUE TO
FORECAST HIGHS WELL BELOW GUIDANCE ON TUESDAY AS MODELS LIKELY DO
NOT HAVE A GOOD HANDLE OF THE STRENGTH OF THE WEDGE.
SOME UNCERTAINTY DEVELOPS DURING THE MID-WEEK PERIOD AS MODELS HAVE
BEGUN TO TREND TOWARD THE SOLUTION OF LOW PRESSURE TRACKING ACROSS
THE EASTERN GULF OF MEXICO ON WEDNESDAY...THEN SHIFTING/REDEVELOPING
OVER THE SOUTHWEST ATLANTIC ON THURSDAY. ACCOUNTING FOR THE LATEST
MODEL TRENDS...THE FORECAST REFLECTS A SLIGHT CHANCE OF SHOWERS
ACROSS NORTH COASTAL GEORGIA ON WEDNESDAY...ACROSS ALL COASTAL AREAS
WEDNESDAY NIGHT...THEN SHIFTING NORTH AND EAST OF THE AREA FOR
THANKSGIVING DAY. IF THE MODELS CONTINUE THE TREND IN THIS
DIRECTION...THEN RAIN CHANCES MAY NEED TO BE INCREASED AND/OR
EXPANDED ACROSS MORE OF THE FORECAST AREA.
MEDIUM RANGE GUIDANCE IS IN GOOD AGREEMENT DEPICTING A BROAD UPPER
LEVEL TROUGH SHIFTING OVER THE EASTERN U.S. FRIDAY INTO
SATURDAY...AS STRONG HIGH PRESSURE AT THE SURFACE GRADUALLY BUILDS
FROM THE WEST. THIS WILL RESULT IN DRY CONDITIONS...HOWEVER ROUNDS
OF STRONG COLD AIR ADVECTION WILL DEVELOP AS REINFORCING COLD FRONTS
SHIFT THROUGH AT THE SURFACE. THIS WILL LEAD TO MUCH BELOW NORMAL
TEMPERATURES. THERE MAY EVEN BE SOME FROST/FREEZE CONCERNS
INLAND...WITH THE COOLEST TEMPERATURES EXPECTED FRIDAY NIGHT.
THE SURFACE HIGH WILL SETTLE OVER THE REGION ON SUNDAY WITH WEAK
RIDGING BUILDING ALOFT. THIS WILL ALLOW FOR SLOWLY MODERATING
TEMPERATURES BUT WILL ALSO KEEP DRY CONDITIONS IN PLACE.
&&
.AVIATION /21Z SUNDAY THROUGH FRIDAY/...
BACK EDGE OF THE STEADY RAINS WILL MOVE THROUGH KSAV THIS
EVENING...BUT WILL TAKE THE FIRST PART OF TONIGHT AT KCHS BEFORE
TAPERING TO DRIZZLE. MVFR AND/OR IFR CONDITIONS WILL PREVAIL THROUGH
THE ENTIRE FORECAST PERIOD...ALTHOUGH IF WE ARE ABLE TO OBTAIN
ENOUGH OF A DOWNSLOPING NW WIND AT KSAV THERE MIGHT BE A SMALL
PERIOD OF VFR CIGS MONDAY AFTERNOON. THAT HOWEVER APPEARS UNLIKELY
AS OF SUNDAY AFTERNOON.
VAD WIND PROFILE SUGGESTS THAT WIND SHEAR IS OCCURRING AT
KSAV...WHICH WILL CONTINUE THROUGH 03Z BEFORE ENDING.
EXTENDED AVIATION OUTLOOK...MVFR OR LOWER CONDITIONS ARE LIKELY
MONDAY INTO TUESDAY. VFR CONDITIONS SHOULD BECOME PREVALENT
WEDNESDAY THROUGH FRIDAY.
&&
.MARINE...
GRADIENT IS EXPECTED TO TIGHTEN THIS EVENING AS THE COASTAL TROUGH
STRENGTHENS OFF OUR COAST. BRIEF NE WIND SURGE WILL PROBABLY TAKE
PLACE BEFORE A CLOSED SURFACE LOW DEVELOPS NE OF THE WATERS AFTER
MIDNIGHT. WILL CONTINUE SMALL CRAFT ADVISORIES FOR ALL NEARSHORE
WATERS AND THE HARBOR THROUGH MIDNIGHT WITH AN ADVISORY RUNNING
THROUGH 11 AM MONDAY FOR THE OFFSHORE GA WATERS FOR 6 FT SEAS.
RAPIDLY IMPROVING CONDITIONS WILL OCCUR ON MONDAY AS FLOW BECOMES
OFFSHORE AND GRADIENT SIGNIFICANTLY WEAKENS.
MONDAY NIGHT THROUGH FRIDAY...A WEDGE OF HIGH PRESSURE INLAND WILL
KEEP A NORTHERLY FLOW IN PLACE OVER THE COASTAL WATERS THROUGH
WEDNESDAY NIGHT WITH WINDS LESS THAN 15 KT. A COLD FRONT WILL SHIFT
OFFSHORE THURSDAY...WITH STRONG COLD AIR ADVECTION DEVELOPING IN ITS
WAKE. THIS COULD RESULT IN THE DEVELOPMENT OF SMALL CRAFT ADVISORY
CONDITIONS...ESPECIALLY OVER THE OUTER GEORGIA WATERS...BY LATE IN
THE WORK WEEK.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR AMZ330-350-
352-354.
SMALL CRAFT ADVISORY UNTIL 11 AM EST MONDAY FOR AMZ374.
&&
$$
JRL/JAQ
000
FXUS62 KCAE 222002
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
302 PM EST SUN NOV 22 2009
.SYNOPSIS...
LOW PRESSURE ALONG THE GULF COAST WILL MOVE SLOWLY NORTHEAST
ACROSS THE FLORIDA PANHANDLE THIS EVENING THEN REFORM OFF THE GA
COAST LATE TONIGHT. HIGH PRESSURE WILL CONTINUE TO WEDGE INTO THE
CAROLINAS FROM THE NORTH THROUGH TUESDAY. A BRIEF RETURN TO MILD
TEMPERATURES IS EXPECTED WEDNESDAY AND THURSDAY AHEAD OF A COLD
FRONT. DRY AND COOL HIGH PRESSURE WILL BUILD IN NEXT WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
STRONG WARM AIR ADVECTION/ISENTROPIC LIFT OVER THE AREA THIS
AFTERNOON/EVENING MOVES NORTH OVERNIGHT. SHORT WAVE CROSSING AL/GA
LIFTS NORTHEAST ACROSS THE WESTERN CAROLINAS TONIGHT. WATER VAPOR
SHOWING MID/UPPER LEVEL DRY SLOT OVER SRN GA WORKING ITS WAS INTO
WRN SC.
SURFACE LOW IN THE NORTHERN GULF OF MEXICO WILL CONTINUE TO
WEAKEN...TO RE-DEVELOP ALONG AN INVERTED TROUGH OFF THE SOUTHEAST
COAST. WIDESPREAD RAIN THIS AFTERNOON AND EVENING WILL DECREASE IN
COVERAGE TONIGHT. STILL EXPECT LINGERING DRIZZLE AND A CHANCE OF
LIGHT RAIN. NOT A LOT OF CHANGE IN TEMPERATURES OVERNIGHT...LOWS IN THE
MID/UPPER 40S.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
WEDGE PATTERN CONTINUES WITH SOUTHWEST FLOW ALOFT AND NORTHEAST WIND
AT THE SURFACE. SHALLOW MOISTURE TRAPPED BENEATH A STRONG INVERSION
WILL HOLD CONSIDERABLE CLOUDINESS ACROSS THE AREA MONDAY THROUGH
TUESDAY NIGHT. EXPECT SOME LINGERING LIGHT RAIN AND AREAS OF DRIZZLE
ESPECIALLY MONDAY. WILL UNDERCUT GUIDANCE MAX TEMPS HIGH TEMPS.
HIGHS IN THE 50S AND LOWS IN THE 40S.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
12Z ECMWF AND 12Z GFS ARE IN PRETTY GOOD AGREEMENT WEDNESDAY
THROUGH SUNDAY. A CLOSED LOW CROSSES THE GREAT LAKES REGION
THROUGH WEDNESDAY. A STRONG SHORTWAVE MOVES FROM THE DAKOTAS TO
THE CENTRAL PLAINS TO DEEPEN THE UPPER LOW OVER THE CENTRAL MS
VALLEY AND OHIO VALLEY THROUGH FRIDAY. THE SURFACE LOW OVER THE
GREAT LAKES REGION SLOWLY MOVES NORTHEAST, DRAGGING A COLD FRONT
ACROSS THE SOUTHEASTERN STATES ON THURSDAY. SINCE MOISTURE IS
LIMITED, EXPECT TO SEE SOME CLOUDINESS BUT LITTLE IF ANY RAINFALL.
MORE PLENTIFUL MOISTURE LOOKS TO REMAIN SOUTH AND EAST OF THE
AREA AND ACROSS THE CENTRAL APPALACHIANS. WILL KEEP THE FORECAST
DRY WEDNESDAY AND THURSDAY.
LARGE MID AND UPPER LEVEL LOW PRESSURE OVER THE EASTERN HALF OF
THE COUNTRY MOVES OFF THE COAST SATURDAY. SURFACE HIGH PRESSURE
BUILDING IN FROM THE WEST FOR NEXT WEEKEND, BRINGING A COOL AND
DRY AIR MASS.
&&
.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
RAIN IS EXPECTED AT ALL THE TERMINALS AS WARM ADVECTION CONTINUES
PRODUCE BANDS OF RAIN MOVING NORTHWARD OUT OF GEORGIA. CIGS AND
VSBYS WILL GENERALLY START OUT VFR BUT CIGS WILL BE REDUCED TO
MVFR AND VSBYS TO POSSIBLY IFR IN THE PERIODS OF RAIN. FORECAST
SOUNDINGS AND TIME HEIGHT PLOTS INDICATE A GRADUAL SATURATION OF
THE ATMOSPHERE AND AS COLD AIR DAMMING WEDGE TAKES SHAPE...EXPECT
DETERIORATING CONDITIONS THROUGH THE EVENING AND OVERNIGHT HOURS.
MVFR/IFR CIGS ALL TERMINALS BY 03Z AND LIFR CIGS AFTER 09Z. VSBYS
WILL BE A BIT TOUGHER TO CALL DEPENDING ON HOW HEAVY DRIZZLE OR
SCATTERED SHOWERS ARE OVERNIGHT...SO GENERALLY KEPT VSBYS IN THE
MVFR RANGE AT THIS TIME...BUT CONFIDENCE IS NOT HIGH. LOW
CONDITIONS SHOULD LINGER INTO THE DAY MONDAY WITH CONTINUED
NORTHEASTERLY FLOW AND COOL HIGH PRESSURE ACROSS THE AREA.
EXTENDED AVIATION OUTLOOK...WIDESPREAD MVFR OR IFR CONDITIONS WILL
CONTINUE MONDAY AFTERNOON INTO TUESDAY.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
SYNOPSIS...10
NEAR TERM...10
SHORT TERM...10
LONG TERM...10
AVIATION...HC
000
FXUS62 KGSP 221953
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
253 PM EST SUN NOV 22 2009
.SYNOPSIS...
A COOL AND MOIST WEDGE OF HIGH PRESSURE WILL LINGER ATOP THE REGION
THROUGH AT LEAST MONDAY. MILDER AIR WILL TRY TO PUSH BACK INTO THE
AREA TUESDAY AHEAD OF AN APPROACHING COLD FRONT WHICH IS FORECAST
TO MOVE THROUGH ON THURSDAY.
&&
.NEAR TERM /THROUGH MONDAY/...
THE AREA OF STRONG ASCENT...ASSOCIATED WITH MID-LEVEL FRONTOGENESIS
AND A COUPLED UPPER JET...WILL MOVE NORTHEAST OF THE REGION EARLY
THIS EVENING. WHILE THAT WILL BE THE END OF DEEP LAYER
FORCING...THERE REMAINS GOOD LLVL FORCING IN THE FORM OF LLVL WARM
ADVECTION ALONG THE H8 FRONT. THE FRONT CURRENTLY EXTENDS ACROSS THE
MIDLANDS AND N CNTRL GA...BUT IT WILL LIFT NORTHWARD OVERNIGHT. THE
BEST FORCING WILL OCCUR BETWEEN 00 AND 06 UTC...PARTICULARLY EAST OF
THE HIGHER MTN ELEVATIONS. I HAVE CATEGORICAL POPS OVER MOST OF THE
FA FOR THE OVERNIGHT HOURS.
AREAS ALONG THE I-77 CORRIDOR HOLD ON THE WARM ADVECTION THROUGH THE
MORNING HOURS ON MONDAY...AND I/VE KEPT POPS IN THIS AREA HIGH
THROUGH THE FIRST HALF OF THE DAY. THIS IS SUPPORTED BY THE SREF QPF
FIELDS. MAX TEMPS WILL HARDLY BUDGE TOMORROW AS THE CLASSICAL COLD
AIR DAMMING TRANSITIONS INTO MORE OF AN IN SITU EVENT. THE HIGHER
MTN ELEVATIONS ALONG THE TN LINE MAY SEE SOME CLEARING...BUT
EVERYONE ELSE LOOKS TO STAY CLOUDY...DRIZZLY AND FOGGY THROUGH THE
DAY. IN FACT...THE FOG MAY BECOME WORSE DURING THE DAY AS THE COLD
DOME BEGINS TO WEAKEN.
&&
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
AS OF 115 PM SUNDAY...LINGERING LLVL MOISTURE/SFC RIDGING WITHIN
INCREASINGLY WEAK FLOW REGIME EXPECTED TO ALLOW WEDGE CONDITIONS TO
CONTINUE MONDAY NIGHT. FORCING FOR PCPN IS MINIMAL...WITH JUST
SPOTTY LIGHT RAIN/DRIZZLE STILL PSBL. IT IS NOT CONCLUSIVE WHETHER
ENUF MIXING WILL BE SEEN TO PREVENT FOG FORMATION OUTSIDE OF THE
MTN VALLEYS. TUESDAY IS STILL SHAPING UP TO BE A TRICKY FCST AS THE
DEGREE OF OVERALL IMPROVEMENT IN SKY CONDITIONS REMAIN QUESTIONABLE
WITHIN THE WEAKENING WEDGE...GIVING THE LIGHT AND VARIABLE FLOW
WITHIN THE POTENTIAL SCOURING LAYERS. REGIONALLY...THE BIGGEST MODEL
DISCREPANCY SEEMS TO BE THE MET MOS FCST OF LOW OVC ALL DAY AND
MUCH COOLER MAXES...ESPECIALLY ALONG AND EAST OF I-77. AT THIS
JUNCTURE...WILL GIVE AT LEAST PARTIAL PROPS TO THIS SOLUTION...AND
COOL FROM PERSISTENCE A CATEGORY OR SO ACRS THE EASTERN
PIEDMONT...WITH THE LATEST MOS BLEND ELSEWHERE RESULTING IN PERHAPS
A DOWNWARD DEG OR TWO TWEAK TO GOING MAXES.
NOTWITHSTANDING WHATEVER DEGREE OF LOWER CLOUDS WHICH MAY OR MAY NOT
HAVE MIXED OUT TUESDAY AFTERNOON...WHICH WOULD THEN LINGER INTO
TUESDAY NIGHT...SENSIBLE WX EXPECTED TO BE LIMITED TO NOTHING MORE
THAN A SPOTTY LIGHT SHOWER THREAT WITHIN THE WSW FLOW AHEAD OF FAST
MOVING IMPULSE WITHIN SW FLOW ALOFT. EXPECTING TO MAKE LITTLE CHANGE
TO INHERITED PRE-FRONTAL MINS...SVRL CATEGORIES ABOVE CLIMO.
LINGERING SLIGHT SHOWER CHANCES TO CONTINUE WEDNESDAY MORNING
AS AFOREMENTIONED IMPULSE MOVES QUICKLY THRU. OTHERWISE...A FAIR
AND MILDER DAY REMAINS ON TAP.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
AS OF 240 PM SUNDAY...THE MEDIUM RANGE APPEARS TO BE SHAPING UP AS A
PERIOD OF EARLY WINTER WEATHER...ACROSS THE MTNS AT LEAST. THE
FORECAST STUCK FAIRLY CLOSE TO THE HPC SCENARIO...WHICH FAVORS THE
ECMWF MORE THAN THE OTHER OPERATIONAL MODELS. THE FIRST CONCERN IS
THE THANKSGIVING FORECAST. AT THIS TIME...IT APPEARS THAT ANY SRN
STREAM ENERGY WILL TRACK PAST TOO FAR TO THE SOUTH TO AFFECT THE
WESTERN CAROLINAS. THE MODELS HAVE A SURFACE LOW FAR ENOUGH OFF THE
SOUTHEAST COAST WEDNESDAY NIGHT AND THURSDAY TO MISS US. INSTEAD...
THE POTENT UPPER LOW OVER THE MIDWEST WILL SEND A SHORT WAVE DOWN
ACROSS THE TN VALLEY AND SRN APPALACHIANS. FORCING LOOKS GREAT BUT
THE SYSTEM WILL BE MOISTURE STARVED...SO POP WAS LIMITED TO LOW END
CHC AND SLIGHT CHANCE FAVORING NC...AS IS USUALLY THE CASE WITH
SYSTEMS COMING IN FROM THE W OR NW. THE FRONT SHOULD MOVE THROUGH
LATE IN THE DAY AND WILL USHER IN MUCH COLDER AIR.
WITH THAT...THE STAGE SHOULD BE SET FOR POTENTIALLY THE FIRST REAL
NW FLOW SNOW EVENT OF THE SEASON. PARTIAL THICKNESS VALUES DROP AND
850MB TEMPS DIVE BELOW ZERO IN THE EVENING AS MOISTURE IS PUSHED UP
THE TN SIDE OF THE MTNS. SHOWERS SHOULD BREAK OUT IN THE UPSLOPE
AREAS IN THE EVENING AND WILL CHANGE OVER TO SNOW SHOWERS BY LATE
EVENING. ONCE ESTABLISHED...PRODUCTION OF PRECIP IN THE NW FLOW
SHOULD CONTINUE INTO FRIDAY EVENING. FRIDAY IS AN INTERESTING DAY.
HAVE CUT HIGH TEMPS OVER THE MTNS BASED ON THE CLOUDS AND SHOWER
ACTIVITY BUT NOT ENOUGH TO KEEP SHOWERS IN A SOLID FORM. I SUSPECT
THAT MY HIGH TEMP IS OPTIMISTICALLY HIGH...IN WHICH CASE IT WOULD
FOLLOW THAT SHOWERS WOULD REMAIN IN THE FORM OF SNOW OR RAIN/SNOW
MIXED FOR A LONGER PERIOD OF THE DAY. AT ANY RATE...SHOWERS SHOULD
CHANGE BACK TO SNOW IN THE EVENING BEFORE ENDING LATE FRIDAY NIGHT.
SATURDAY AND SUNDAY SHOULD SEE TEMPS GRADUALLY REBOUND TO
CLIMATOLOGICAL VALUES WITH HIGH PRESSURE BUILDING IN FROM THE WEST.
HAVE KEPT THE NEXT SYSTEM AT BAY TO THE WEST ON SUNDAY FOR THE TIME
BEING.
&&
.AVIATION /20Z SUNDAY THROUGH FRIDAY/...
AT KCLT...A NARROW BAND OF MODERATE TO HEAVY RAIN WILL MOVE ACROSS
THE AIRFIELD BETWEEN 19 AND 20 UTC. WINDS WILL BE LIGHT UP TO THAT
TIME...THEN THEY WILL INCREASE UP TO AROUND 10 KTS FROM THE NE...AND
STAY FROM THAT DIRECTION FOR THE FORECAST PERIOD. THE WINDS WILL BE
STRONG ENOUGH UP AROUND 2KFT THAT LOW LEVEL WIND SHEAR COULD BE A
PROBLEM LATER TODAY AND TONIGHT. I HAVEN/T PUT IT IN THE TAF...BUT
IT/S SOMETHING TO KEEP AN EYE ON. CIGS SHOULD FALL INTO THE MVFR
RANGE A COUPLE HOURS AFTER THE RAIN BEGINS. CIGS WILL FALL INTO THE
IFR...OR LIFR...RANGE OVERNIGHT AND SHOULD HOLD AT THAT LEVEL MUCH
OF THE DAY ON MONDAY.
ELSEWHERE...RAIN HAS DEVELOPED OVER MUCH OF THE REGION. THIS IS
RESULTING IN GRADUALLY LOWERING CIGS AND VSBYS. THE CIGS AND VSBYS
WILL VARY A BIT OVER THE NEXT FEW HOURS BEFORE BECOMING MORE SOLIDLY
MVFR LATER IN THE AFTN. CIGS SHOULD FALL INTO THE IFR OR EVEN LIFR
RANGE TONIGHT AND HOLD AT THAT LEVEL THROUGH MOST OF THE DAY ON
MONDAY. WINDS WILL BE NORTHEAST THROUGH THE PERIOD...AND MAY EVEN BE
A LITTLE GUSTY AT TIMES. WINDS AT KAVL...HOWEVER...WILL BE MORE OUT
OF THE N TO NNW.
OUTLOOK...WIDESPREAD IFR CONDITIONS ARE EXPECTED TO CONTINUE MONDAY
NIGHT. MODEL GUIDANCE SHOWS IMPROVEMENT TUESDAY BUT MOST LIKELY AT
BEST MVFR SHOULD BE EXPECTED UNTIL WEDNESDAY. A COLD FRONT WILL
BRING WINDY CONDITIONS ON THURSDAY AND A FEW RESTRICTIONS IN SHOWERS
IN THE MOUNTAINS.
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...CSH
NEAR TERM...MCAVOY
SHORT TERM...CSH
LONG TERM...PM
AVIATION...MCAVOY
000
FXUS62 KCHS 221755
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
1255 PM EST SUN NOV 22 2009
.SYNOPSIS...
AN AREA OF LOW PRES WILL TRACK ALONG THE GULF COAST STATES TODAY
THEN RE-DEVELOP OVER OUR ADJACENT ATLC WATERS TONIGHT. THE LOW
WILL THEN LIFT NE OFF THE CAROLINA COAST MON INTO TUE...AS HIGH
PRES REMAINS ENTRENCHED OVER COASTAL SOUTH CAROLINA AND GEORGIA. A
SERIES OF DRY COLD FRONTS WILL SHIFT THROUGH THE AREA FROM LATE
WEEK INTO THE UPCOMING WEEKEND AS HIGH PRES SLOWLY BUILDS IN FROM
THE W.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
THE UPPER LOW WAS SPINNING ITS WHEELS OVER SOUTHERN ALABAMA THIS
MORNING WHILE THE SURFACE LOW HAD PUSHED INTO THE EASTERN GULF OF
MEXICO. THE VORT MAX ASSOCIATED WITH THE UPPER LOW IS SLOWLY
PUSHING INTO CENTRAL GA TOWARD THE SC MIDLANDS. THE HEAVIEST AND
MOST WIDESPREAD PRECIPITATION HAS BEEN OCCURRING AHEAD OF THIS
FEATURE...MAINLY WEST OF OUR FORECAST AREA. MEANWHILE HIGH
PRESSURE REMAINS ENTRENCHED FROM THE MID-ATLANTIC REGION THROUGH
THE CAROLINAS INTO SOUTHERN GA. DESPITE THE INCREASE IN ISENTROPIC
ASCENT ABOVE THE HIGH PRESSURE WEDGE...A CONSIDERABLE DRY SLOT
OVER THE EASTERN HALF OF THE AREA HAS PREVENTED MUCH IN THE WAY OF
MEASURABLE RAINFALL. LATER THIS AFTERNOON WE SHOULD SEE THE
COASTAL TROUGH OFF THE SC COAST STRENGTHEN WHICH SHOULD IN TURN
IMPROVE RAIN CHANCES ACROSS THE NORTHEASTERN PORTIONS.
HOWEVER...UNTIL THAT OCCURS WE DO NOT EXPECT TO SEE MORE THAN
SCATTERED COVERAGE OF RAIN EAST OF I-95. WE PARED BACK POPS OVER
THE EASTERN HALF OF THE AREA FOR MUCH OF THE DAY ALTHOUGH AT LEAST
LIKELY POPS WILL PREVAIL EVERYWHERE EXCEPT COASTAL CHARLESTON
COUNTY.
THUNDERSTORM POTENTIAL STILL APPEARS VERY LOW BUT AN AREA OF
6-6.5C MID-LEVEL LAPSE RATES MOVING THROUGH THIS AFTERNOON WITH
THE STRONGEST DYNAMICS COULD SUPPORT AN ISOLATED TSTM IN SOUTHERN
AREAS. TEMP FORECAST STILL APPEARS ON TRACK WITH HIGHS REMAINING
IN THE 50S.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM MONDAY/...
SURFACE LOW PRES ALONG S ALABAMA AND THE FLORIDA PANHANDLE WILL
WEAKEN BY THIS EVENING...THEN REDEVELOP OFF THE COAST OF THE
GEORGIA/FLORIDA BORDER...THEN TRACK NE ALONG THE W WALL OF THE
GULF STREAM E OF CHARLESTON BY LATE TONIGHT. THIS KEEPS A SOLID
WEDGE PATTERN GOING FOR OUR AREA. TEMPERATURES SHOULD BE COOL AND
FAIRLY STEADY. A PINCHED GRADIENT SUPPORTING BREEZY CONDITIONS
ALONG THE SOUTH CAROLINA COAST SHOULD RELAX LATE TONIGHT AS THE
EJECTING LOW BUCKLES THE WEDGE NW OVER EASTERN SOUTH CAROLINA.
LOCATIONS SUCH AS CHARLESTON...ST. GEORGE AND MONCKS CORNER MAY
SEE THEIR MOST SIGNIFICANT RAINS BETWEEN DUSK AND MIDNIGHT AS THE
DYNAMICS TRAVERSE THE AREA. ISOLATED ELEVATED THUNDER POSSIBLE E
OF I-95 IN SOUTH CAROLINA DURING THE EVENING. LATER TONIGHT...MID
LEVEL DRYING STRIPS UPPER MOISTURE AND LEAVES SOUNDING PROFILES
SUPPORTIVE OF LIGHTER RAINS AND DRIZZLE AFTER MIDNIGHT...ESPECIALLY
OVER SE GEORGIA WHERE PRECIP MAY JUST BE DRIZZLE LATE. NEAR COASTAL
BREEZES SHOULD ALSO SUBSIDE LATE AS THE PRES GRADIENT WEAKENS.
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
GUIDANCE IS IN GOOD AGREEMENT TRACKING SURFACE LOW PRESSURE
NORTHEASTWARD OFF THE CAROLINA COAST MONDAY THROUGH TUESDAY...WITH
NORTHERLY FLOW STRENGTHENING THE HIGH PRESSURE WEDGE ACROSS THE
FORECAST AREA. DEEP MOISTURE WILL HAVE SHIFTED OUT OF THE REGION BY
DAYBREAK MONDAY...BUT MODEL RELATIVE HUMIDITY TIME/HEIGHT CROSS
SECTIONS CONTINUE TO INDICATE A NEARLY SATURATED BOUNDARY LAYER
ACROSS THE ENTIRE FORECAST AREA THROUGH TUESDAY. GIVEN THE VERY
LIGHT WIND FIELDS OUT OF A NORTH-NORTHEAST THROUGH NORTH-NORTHWEST
DIRECTION AND THE LOW SUN ANGLE...EXPECT THE LOW LEVEL INVERSION TO
HOLD STRONG ACROSS THE AREA...RESULTING IN CLOUDY/MOSTLY CLOUDY
CONDITIONS ALONG WITH SOME LIGHT RAIN AND/OR AREAS OF DRIZZLE
IMPACTING THE REGION THROUGH TUESDAY.
MODEL SOLUTIONS ARE FOR THE MOST PART IN AGREEMENT FOR THE MID-LATE
WEEK TIME FRAME. THE EXCEPTION TO THIS IS THE ECMWF WHICH CONTINUES
TO ADVERTISE DEVELOPMENT OF A WAVE OF LOW PRESSURE TRACKING
NORTHEASTWARD OFF THE GEORGIA AND CAROLINA COAST WEDNESDAY NIGHT AND
THANKSGIVING DAY. GIVEN THE STRONG MODEL CONSENSUS OF THE
GFS/CANADIAN/UKMET SOLUTIONS...AS WELL AS THE ECMWF TRENDING TOWARD
THE SOLUTION OF THE OTHER OPERATIONAL MODELS...WILL KEEP THE
FORECAST RAIN FREE WEDNESDAY THROUGH THANKSGIVING DAY.
HIGH PRESSURE IS THEN EXPECTED TO BUILD BACK INTO THE AREA THURSDAY
NIGHT AND REMAIN THE DOMINANT WEATHER FEATURE THROUGH
SATURDAY...WITH RAIN FREE CONDITIONS ANTICIPATED ACROSS THE REGION.
&&
.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
CONDITIONS HAVE BEEN SLOW TO DETERIORATE TODAY DUE TO A SOLID DRY
SLOT ACROSS THE EASTERN PORTION OF THE AREA. A HEAVIER BATCH OF
RAIN IS NOW MOVING INTO SOUTHEAST GEORGIA AND SHOULD SOON DROP
CEILINGS TO IFR AT KSAV. A FEW MORE HOURS OF VFR CONDITIONS APPEAR
LIKELY AT CHS BEFORE A STRENGTHENING OFFSHORE TROUGH AND
INCREASING MOISTURE FROM THE SW DROP CEILINGS TO MVFR. PREVAILING IFR
PROBABILITIES ARE NOT AS HIGH AT CHS TONIGHT DUE TO A DEEPER COOL
WEDGE AT THE SURFACE AND BETTER MOISTURE INLAND. HINTED AT SOME
LOWER CEILINGS LATE TONIGHT BUT MAINTAINED PREVAILING MVFR
CONDITIONS AT THIS TIME. WE IMPROVED CEILINGS TO MVFR AFTER
DAYBREAK MONDAY AT SAV SINCE SOME DRIER AIR LOOKS TO SHIFT IN FROM
THE NW.
EXTENDED AVIATION OUTLOOK...MVFR OR LOWER CONDITIONS ARE LIKELY
MON INTO TUE. VFR CONDITIONS MAY RETURN WED THROUGH THU.
&&
.MARINE...
WINDS AND SEAS CONTINUE TO INCREASE THIS MORNING AS THE SURFACE WEDGE
DIGS IN FROM THE N AND PRES FALLS INCREASE OVER THE NE GULF OF MEXICO
AND N FLORIDA. WE HAVE RAISED SMALL CRAFT ADVISORIES FOR ALL
WATERS INCLUDING THE CHARLESTON HARBOR TODAY. A PINCHED GRADIENT
WILL GRADUALLY TILT NW INTO COASTAL SOUTH CAROLINA LATE TODAY AND
THIS EVENING...WITH NE WINDS BUILDING TO 20 TO 25 KT...LOCALLY
GUSTIER CONDITIONS POSSIBLE. IN SE GEORGIA...WINDS REACHING NEAR
20 KT AT THE SAVANNAH RIVER ENTRANCE AND POSSIBLY A BIT FURTHER S
SUGGEST SEAS AT LEAST 4-6 FT TODAY.
A WAVE OF LOW PRESSURE WILL TRACK NORTHEAST OFF THE CAROLINA
COAST MONDAY THROUGH TUESDAY...AS SURFACE HIGH PRESSURE REMAINS
STATIONARY OVER SOUTH CAROLINA AND GEORGIA AS WELL AS THE
NEARSHORE COASTAL WATERS. A WEAK COLD FRONT WILL THEN SHIFT
THROUGH THE WATERS WEDNESDAY NIGHT...WITH HIGH PRESSURE THEN
BUILDING BACK INTO THE AREA FOR THURSDAY.
COULD SEE SOME LINGERING SMALL CRAFT CONDITIONS THROUGH MONDAY
MORNING DUE TO ELEVATED SEAS OVER THE NORTHERN SOUTH CAROLINA
NEARSHORE WATERS AND THE OFFSHORE GEORGIA WATERS.
THEREFORE...EXTENDED THE SMALL CRAFT ADVISORY FOR THESE MARINE ZONES
THROUGH LATE MONDAY MORNING. ELSEWHERE...WINDS AND SEAS ARE EXPECTED
TO REMAIN BELOW SMALL CRAFT THRESHOLDS THROUGH THURSDAY.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR AMZ330-352-
354.
SMALL CRAFT ADVISORY UNTIL 11 AM EST MONDAY FOR AMZ350-374.
&&
$$
JRL
000
FXUS62 KGSP 221753
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1253 PM EST SUN NOV 22 2009
.SYNOPSIS...
A COOL AND MOIST WEDGE OF HIGH PRESSURE WILL LINGER ATOP THE REGION
THRU AT LEAST MONDAY. MILDER AIR WILL TRY TO PUSH BACK INTO THE AREA
TUESDAY AHEAD OF AN APPROACHING COLD FRONT WHICH IS FORECAST
TO MOVE THROUGH ON THURSDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
BOTH THE NAM AND GFS TRANSLATE AN AREA OF STRONG H7 FRONTOGENESIS
ACROSS THE UPSTATE AND WRN NC FOOTHILLS AND PIEDMONT THROUGH THE
AFTN HOURS. THIS FORCING HAS RESULTED IN A BAND OF HIGH BASED
PCPN...FALLING THROUGH A DEEP LAYER OF DRY AIR. IN RESPONSE...A
RADAR BRIGHT BAND HAS FORMED OVER THE SW PART OF THE UPSTATE AS OF
1530 UTC. THIS AREA OF PCPN WILL CONTINUE TO TRANSLATE NE ACROSS THE
REGION OVER THE NEXT SEVERAL HOURS. PCPN AMOUNTS SHOULDN/T BE ALL
THAT HEAVY UNDER THE BAND...DESPITE THE HIGH REFLECTIVITIES.
STILL...MEASURE RAINFALL WILL SPREAD ACROSS THE FA A LITTLE MORE
QUICKLY THAN ORIGINALLY EXPECTED...AND I/VE RAISED POPS THE REST OF
THE DAY. AS THE FORCING MOVES INTO THE DEEPER COLD/DRY AIRMASS ALONG
THE LEE ASSOCIATED WITH COLD AIR DAMMING...THE PCPN MAY NOT ACTUALLY
REACH THE GROUND...AND I/VE KEPT THE POPS A LITTLE LOWER ALONG AND
NORTH OF I-40. I INCREASED THE WINDS A LITTLE TO ACCOUNT FOR A
STRENGTHENING BARRIER JET...BUT EVERYTHING ELSE LOOKS GOOD.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
AS OF 230 AM EST SUNDAY...SOUTHWEST UPPER FLOW IS EXPECTED OVER THE
SOUTHEAST ON MONDAY...WITH SHORTWAVES CROSSING THE SOUTHERN
APPALACHIANS EARLY AND LATE IN THE DAY. AN UPPER LOW CROSSES THE
CENTRAL PLAINS FROM MONDAY NIGHT THROUGH WEDNESDAY NIGHT.
A SURFACE RIDGE WILL REMAIN ALONG THE EAST COAST MONDAY AND
TUESDAY...WITH ISENTROPIC UPGLIDE OVER IT THROUGH MONDAY...
SUPPORTING EXTENSIVE CLOUD COVER AND HIGH POPS. BY MONDAY NIGHT THE
MODELS DISAGREE ON THE AMOUNT AND LOCATION OF LINGERING UPGLIDE
FLOW...BUT IN NO CASE IS ANYTHING MORE THAN WEAK DOWNGLIDE SHOWN.
CLOUD COVER WILL BE INCREASED MONDAY NIGHT AND TUESDAY...AS THE CASE
FOR SCOURING THE LOW LEVEL MOISTURE IS WEAK. SMALL POPS WILL BE
MAINTAINED ALONG THE BLUE RIDGE ESCARPMENT MONDAY EVENING...UNTIL
SURFACE WINDS BACK TO THE NORTH. SURFACE WINDS VEER TO NORTHEAST
TUESDAY...AND WITH A LIGHT UPSLOPE COMPONENT...SMALL POPS WILL BE
REINTRODUCED TO THE BLUE RIDGE. AS A SURFACE FRONT APPROACHES
TUESDAY NIGHT...THE MODELS SHOW MOIST SOUTHERLY UPSLOPE FLOW
DEVELOPING...SUPPORTING INCREASING CLOUD COVER AND POPS INCREASING
FROM THE WEST.
WITH COLD AIR DAMMING ONGOING MONDAY...A LOW DIURNAL TEMPERATURE
RANGE WILL BE CARRIED. CLOUD COVER SHOULD KEEP MINIMUM TEMPERATURES
UP MONDAY NIGHT. MAXIMUM TEMPERATURES TUESDAY WILL LEAN TOWARD
LINGERING CLOUD COVER...ALTHOUGH THEY ARE SUBSTANTIALLY WARMER THAN
MONDAY. MINIMUM TEMPERATURES TUESDAY NIGHT REMAIN ELEVATED AS
SOUTHERLY FLOW AN MORE CLOUDS ARE EXPECTED.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
AS OF 330 AM SUNDAY...MDLS SHOWING BETTER AGREEMENT DURING THE
MEDIUM RANGE THAN THE PAST COUPLE OF DAYS. THIS RESULTS IN INCREASED
FORECAST CONFIDENCE. HOWEVER...GIVEN THE POSSIBLE SOLN...WILL KEEP
THINGS LOW KEY FOR NOW. REINFORCING UPPER LOW DROPS INTO THE CENTRAL
US TROF...DIGGING IT EVEN DEEPER. STRONG SHORT WAVE ROTATES AROUND
THE LOW AS IT MOVES EAST FRI AND SAT.
AT THE SFC...THERE MAY BE SOME LINGERING SHOWERS WED AS OCCLUDED
FRONT MOVES ACROSS THE AREA. HIGHS ABOVE NORMAL AS DRIER...BRIEFLY
WARMER AIR MASS MOVES IN. THE GULF LOW TRACK ON THE ECMWF HAS MOVED
FARTHER OFF THE COAST...CLOSER TO THE GFS AND GEM TRACKS. THIS
SHOULD HELP KEEP WED NITE DRY BEFORE THE NEXT SYSTEM APPROACHES.
LOWS ABOVE NORMAL.
AS THE UPPER LOW MOVES TOWARD THE AREA THU...A VERY COLD AIR MASS
MOVES INTO THE AREA. THE GEFS HAS H85 TEMPS 1 TO 1.5 STANDARD
DEVIATIONS BELOW NORMAL. ALONG WITH THE COLD IS LOW LEVEL MOISTURE
MOVING IN FROM THE NW. THIS SETS UP THE POTENTIAL FOR A NW FLOW
PRECIP EVENT FROM THU THRU FRI NITE. EVEN THOUGH THE H85 TEMPS
REMAIN BELOW FREEZING...THE SFC TEMPS RISE ABOVE FREEZING DURING THE
DAY. THEREFORE...HAVE PRECIP STARTING AS RAIN THU AFT...THEN
CHANGING TO RAIN THU NITE. THIS TREND CONTINUES FRIDAY AS SNOW
CHANGES TO RAIN DURING THE DAY...THEN BACK TO SNOW OVERNIGHT. SOME
RAIN COULD DEVELOP OUTSIDE OF THE MTNS THU AFTERNOON...BUT PRECIP
SHOULD REMAIN LIMITED TO THE NORMAL MTN LOCATIONS AFTER. KEPT POPS
AT SLIGHT CHC FOR NOW GIVEN THE MDL TENDENCY TO OVER FORECAST THE
PRECIP AND AMOUNT OF COLD AIR FOR THESE EVENTS IN THE MEDIUM RANGE.
IT IS WAY TOO EARLY TO KNOW IF ADVISORY LEVEL OR HIGHER SNOW AMOUNTS
WILL DEVELOP. HIGHS THU BELOW NORMAL WEST AND NEAR NORMAL EAST.
TEMPS THEN BELOW NORMAL THU NITE THRU FRI NITE.
HAVE FCST PRECIP ENDING FRI NITE...BUT IT COULD LINGER SATURDAY. DRY
FCST SAT NITE. TEMPS REMAIN BELOW NORMAL.
&&
.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
AT KCLT...A NARROW BAND OF MODERATE TO HEAVY RAIN WILL MOVE ACROSS
THE AIRFIELD BETWEEN 19 AND 20 UTC. WINDS WILL BE LIGHT UP TO THAT
TIME...THEN THEY WILL INCREASE UP TO AROUND 10 KTS FROM THE NE...AND
STAY FROM THAT DIRECTION FOR THE FORECAST PERIOD. THE WINDS WILL BE
STRONG ENOUGH UP AROUND 2KFT THAT LOW LEVEL WIND SHEAR COULD BE A
PROBLEM LATER TODAY AND TONIGHT. I HAVEN/T PUT IT IN THE TAF...BUT
IT/S SOMETHING TO KEEP AN EYE ON. CIGS SHOULD FALL INTO THE MVFR
RANGE A COUPLE HOURS AFTER THE RAIN BEGINS. CIGS WILL FALL INTO THE
IFR...OR LIFR...RANGE OVERNIGHT AND SHOULD HOLD AT THAT LEVEL MUCH
OF THE DAY ON MONDAY.
ELSEWHERE...RAIN HAS DEVELOPED OVER MUCH OF THE REGION. THIS IS
RESULTING IN GRADUALLY LOWERING CIGS AND VSBYS. THE CIGS AND VSBYS
WILL VARY A BIT OVER THE NEXT FEW HOURS BEFORE BECOMING MORE SOLIDLY
MVFR LATER IN THE AFTN. CIGS SHOULD FALL INTO THE IFR OR EVEN LIFR
RANGE TONIGHT AND HOLD AT THAT LEVEL THROUGH MOST OF THE DAY ON
MONDAY. WINDS WILL BE NORTHEAST THROUGH THE PERIOD...AND MAY EVEN BE
A LITTLE GUSTY AT TIMES. WINDS AT KAVL...HOWEVER...WILL BE MORE OUT
OF THE N TO NNW.
OUTLOOK...WIDESPREAD IFR CONDITIONS ARE EXPECTED TO CONTINUE MONDAY
NIGHT. MODEL GUIDANCE SHOWS IMPROVEMENT TUESDAY BUT MOST LIKELY AT
BEST MVFR SHOULD BE EXPECTED UNTIL WEDNESDAY. A COLD FRONT WILL
BRING WINDY CONDITIONS ON THURSDAY AND A FEW RESTRICTIONS IN SHOWERS
IN THE MOUNTAINS.
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...RWH
NEAR TERM...MCAVOY
SHORT TERM...JAT
LONG TERM...RWH
AVIATION...MCAVOY
000
FXUS62 KCAE 221742
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
1242 PM EST SUN NOV 22 2009
.SYNOPSIS...
A LOW PRESSURE SYSTEM ALONG THE GULF COAST REGION WILL MOVE SLOWLY
NORTHEAST ACROSS THE FLORIDA PANHANDLE TODAY THEN REFORM ALONG THE
CAROLINA COAST TONIGHT. HIGH PRESSURE WILL WEDGE INTO THE
CAROLINAS FROM THE NORTH. THIS PATTERN WILL BRING CLOUDS AND RAIN
TO THE AREA THROUGH MONDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A DEEP UPPER LOW CONTINUES TO LIFT NORTHEAST ACROSS MISSISSIPPI
THIS MORNING WHILE STRONG HIGH PRESSURE AT THE SURFACE STRENGTHENS
AS IT RIDGES DOWN THE EAST COAST. MOISTURE FLUX AND WARM ADVECTION
ARE MAXIMIZED EAST OF THE UPPER LOW AND RESULTING IN A BAND OF
RAIN EXTENDING FROM NORTH GEORGIA SOUTHEASTWARD TOWARDS SAVANNAH.
THIS BAND OF RAIN WILL CONTINUE LIFTING NORTH THROUGH THE LATE
MORNING AND EARLY AFTERNOON HOURS...SPREADING RAIN ACROSS THE
FORECAST AREA.
TEMPERATURES WILL STRUGGLE TO RISE MUCH TODAY WITH CONTINUED
NORTHEASTERLY FLOW AND PRECIPITATION MOVING OVER THE AREA...WHICH
WILL ENHANCE A DEVELOPING COLD AIR DAMMING WEDGE THAT IS
DEVELOPING. IT IS DIFFICULT TO FIGURE OUT HOW MUCH MORE
PRECIPITATION WILL DEVELOP BEHIND THIS INITIAL BAND AS THERE WILL
BE SOME DYNAMICS AVAILABLE AS THE LOW LIFTS OUT BUT A SIGNIFICANT
DRY AIR INTRUSION IS WRAPPING UNDERNEATH THE UPPER LOW AND PUSHING
ITS WAY INTO CENTRAL GEORGIA AT THIS TIME AND WILL MOVE INTO THE
FORECAST AREA BY LATE AFTERNOON. THIS LACK OF MOISTURE IN THE MID
AND UPPER LEVELS WILL LIKELY DECREASE THE CHANCE OF SIGNIFICANT
RAINFALL ACCUMULATION LATE AFTERNOON AND OVERNIGHT BUT LIGHT
SHOWERS WILL LINGER AND DRIZZLE SHOULD DEVELOP OVERNIGHT. CLOUDS
WILL REMAIN THROUGH THE DAY AS CEILINGS GRADUALLY LOWER AS THE
ATMOSPHERE MOISTENS UP.
MADE SOME CHANGES TO THE POP GRIDS TO ACCOUNT FOR SLIGHTLY FASTER
TIMING IN THE WARM ADVECTION BUT THE OVERALL CHANGE IN THE
FORECAST IS NOT GOING TO BE VERY SIGNIFICANT. WILL UPDATE THE ZONE
FORECAST TO REMOVE MORNING WORDING.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/...
WEAKENING SHORT WAVE WILL CROSS GEORGIA INTO THE CAROLINAS
TONIGHT. LOW PRESSURE DEVELOPING ON AN INVERTED TROUGH OFF THE SC
COAST. KEPT CATEGORICAL POPS THROUGH EARLY TONIGHT THEN
DIMINISHING AS ISENTROPIC LIFT SHIFTS NORTH AND WEST. RAINFALL
AMOUNTS RANGING FROM ONE HALF INCH TO AROUND ONE INCH. THE SURFACE
LOW WILL MOVE AWAY FROM THE COAST MONDAY WITH RAIN CHANCES
DECREASING. KEPT CHANCE OF DRIZZLE IN FOR MONDAY NIGHT INTO
TUESDAY WITH WEDGE POSSIBLY HOLDING AND HIGH LOW-LEVEL MOISTURE
SUGGESTED BY MODEL T-SECTIONS. COOLER THAN MOS GUIDANCE MAXIMUM
TEMPERATURE FORECAST DUE TO WEDGE.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
MEDIUM RANGE MODELS DEPICT A SERIES OF MID/UPPER LEVEL LOWS MOVING
ACROSS THE UPPER MIDWEST TO THE EASTERN GREAT LAKES AND
SOUTHEASTERN CANADA TUESDAY NIGHT INTO SATURDAY. ALL IN ALL,
SLIGHT UPPER RIDGING OVER THE SOUTHEAST PART OF THE COUNTRY
TUESDAY IS REPLACED BY A LARGE UPPER TROUGH OVER THE EASTERN
UNITED STATES WEDNESDAY THROUGH FRIDAY. UPPER TROUGH FINALLY MOVES
OFF THE EAST COAST SATURDAY. SURFACE HIGH PRESSURE CENTERED OVER
SOUTHEASTERN CANADA TUESDAY NIGHT RIDGING INTO THE AREA FROM THE
NORTH. SURFACE LOW PRESSURE CROSSING THE GREAT LAKES REGION ON
THANKSGIVING DAY WILL DRAG A COLD FRONT ACROSS THE AREA. MOISTURE
APPEARS LIMITED SINCE THE BEST ISENTROPIC LIFT REMAINS SOUTH AND
EAST OF THE FORECAST AREA. ANY CHANCE FOR RAIN (WHICH IS SLIGHT)
LOOKS LIKE WEDNESDAY INTO THURSDAY MORNING. COOL HIGH PRESSURE
BUILDS IN FOR FRIDAY AND SATURDAY. WILL KEEP THE EXTENDED FORECAST
DRY. SEASONABLY MILD MAX TEMPERATURES WEDNESDAY AND THURSDAY COOL
A FEW DEGREES BELOW NORMAL FOR FRIDAY AND SATURDAY. NIGHTTIME LOWS
IN THE 40S MID-WEEK COOLING TO THE MID AND UPPER 30S BY LATE NEXT
WEEK.
&&
.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
RAIN IS EXPECTED AT ALL THE TERMINALS AS WARM ADVECTION CONTINUES
PRODUCE BANDS OF RAIN MOVING NORTHWARD OUT OF GEORGIA. CIGS AND
VSBYS WILL GENERALLY START OUT VFR BUT CIGS WILL BE REDUCED TO
MVFR AND VSBYS TO POSSIBLY IFR IN THE PERIODS OF RAIN. FORECAST
SOUNDINGS AND TIME HEIGHT PLOTS INDICATE A GRADUAL SATURATION OF
THE ATMOSPHERE AND AS COLD AIR DAMMING WEDGE TAKES SHAPE...EXPECT
DETERIORATING CONDITIONS THROUGH THE EVENING AND OVERNIGHT HOURS.
MVFR/IFR CIGS ALL TERMINALS BY 03Z AND LIFR CIGS AFTER 09Z. VSBYS
WILL BE A BIT TOUGHER TO CALL DEPENDING ON HOW HEAVY DRIZZLE OR
SCATTERED SHOWERS ARE OVERNIGHT...SO GENERALLY KEPT VSBYS IN THE
MVFR RANGE AT THIS TIME...BUT CONFIDENCE IS NOT HIGH. LOW
CONDITIONS SHOULD LINGER INTO THE DAY MONDAY WITH CONTINUED
NORTHEASTERLY FLOW AND COOL HIGH PRESSURE ACROSS THE AREA.
EXTENDED AVIATION OUTLOOK...WIDESPREAD MVFR OR IFR CONDITIONS WILL
CONTINUE MONDAY AFTERNOON INTO TUESDAY.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AVIATION...HC
000
FXUS62 KGSP 221553
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1053 AM EST SUN NOV 22 2009
.SYNOPSIS...
HIGH PRESSURE WILL REMAIN WEDGED IN OVER THE REGION AS A LOW
PRESSURE SYSTEM MOVES EAST ALONG THE GULF COAST...THEN NORTH ALONG
THE CAROLINA COAST TODAY THROUGH MONDAY. THE LOW IS EXPECTED TO
REACH THE NEW ENGLAND COAST BY TUESDAY AS WEAK HIGH PRESSURE REMAINS
OVER THE SOUTHEAST STATES. A WEAK COLD FRONT WILL MOVE THROUGH THE
THE AREA BY THE MIDDLE OF THE WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
BOTH THE NAM AND GFS TRANSLATE AN AREA OF STRONG H7 FRONTOGENESIS
ACROSS THE UPSTATE AND WRN NC FOOTHILLS AND PIEDMONT THROUGH THE
AFTN HOURS. THIS FORCING HAS RESULTED IN A BAND OF HIGH BASED
PCPN...FALLING THROUGH A DEEP LAYER OF DRY AIR. IN RESPONSE...A
RADAR BRIGHT BAND HAS FORMED OVER THE SW PART OF THE UPSTATE AS OF
1530 UTC. THIS AREA OF PCPN WILL CONTINUE TO TRANSLATE NE ACROSS THE
REGION OVER THE NEXT SEVERAL HOURS. PCPN AMOUNTS SHOULDN/T BE ALL
THAT HEAVY UNDER THE BAND...DESPITE THE HIGH REFLECTIVITIES.
STILL...MEASURE RAINFALL WILL SPREAD ACROSS THE FA A LITTLE MORE
QUICKLY THAN ORIGINALLY EXPECTED...AND I/VE RAISED POPS THE REST OF
THE DAY. AS THE FORCING MOVES INTO THE DEEPER COLD/DRY AIRMASS ALONG
THE LEE ASSOCIATED WITH COLD AIR DAMMING...THE PCPN MAY NOT ACTUALLY
REACH THE GROUND...AND I/VE KEPT THE POPS A LITTLE LOWER ALONG AND
NORTH OF I-40. I INCREASED THE WINDS A LITTLE TO ACCOUNT FOR A
STRENGTHENING BARRIER JET...BUT EVERYTHING ELSE LOOKS GOOD.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
AS OF 230 AM EST SUNDAY...SOUTHWEST UPPER FLOW IS EXPECTED OVER THE
SOUTHEAST ON MONDAY...WITH SHORTWAVES CROSSING THE SOUTHERN
APPALACHIANS EARLY AND LATE IN THE DAY. AN UPPER LOW CROSSES THE
CENTRAL PLAINS FROM MONDAY NIGHT THROUGH WEDNESDAY NIGHT.
A SURFACE RIDGE WILL REMAIN ALONG THE EAST COAST MONDAY AND
TUESDAY...WITH ISENTROPIC UPGLIDE OVER IT THROUGH MONDAY...
SUPPORTING EXTENSIVE CLOUD COVER AND HIGH POPS. BY MONDAY NIGHT THE
MODELS DISAGREE ON THE AMOUNT AND LOCATION OF LINGERING UPGLIDE
FLOW...BUT IN NO CASE IS ANYTHING MORE THAN WEAK DOWNGLIDE SHOWN.
CLOUD COVER WILL BE INCREASED MONDAY NIGHT AND TUESDAY...AS THE CASE
FOR SCOURING THE LOW LEVEL MOISTURE IS WEAK. SMALL POPS WILL BE
MAINTAINED ALONG THE BLUE RIDGE ESCARPMENT MONDAY EVENING...UNTIL
SURFACE WINDS BACK TO THE NORTH. SURFACE WINDS VEER TO NORTHEAST
TUESDAY...AND WITH A LIGHT UPSLOPE COMPONENT...SMALL POPS WILL BE
REINTRODUCED TO THE BLUE RIDGE. AS A SURFACE FRONT APPROACHES
TUESDAY NIGHT...THE MODELS SHOW MOIST SOUTHERLY UPSLOPE FLOW
DEVELOPING...SUPPORTING INCREASING CLOUD COVER AND POPS INCREASING
FROM THE WEST.
WITH COLD AIR DAMMING ONGOING MONDAY...A LOW DIURNAL TEMPERATURE
RANGE WILL BE CARRIED. CLOUD COVER SHOULD KEEP MINIMUM TEMPERATURES
UP MONDAY NIGHT. MAXIMUM TEMPERATURES TUESDAY WILL LEAN TOWARD
LINGERING CLOUD COVER...ALTHOUGH THEY ARE SUBSTANTIALLY WARMER THAN
MONDAY. MINIMUM TEMPERATURES TUESDAY NIGHT REMAIN ELEVATED AS
SOUTHERLY FLOW AN MORE CLOUDS ARE EXPECTED.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
AS OF 330 AM SUNDAY...MDLS SHOWING BETTER AGREEMENT DURING THE
MEDIUM RANGE THAN THE PAST COUPLE OF DAYS. THIS RESULTS IN INCREASED
FORECAST CONFIDENCE. HOWEVER...GIVEN THE POSSIBLE SOLN...WILL KEEP
THINGS LOW KEY FOR NOW. REINFORCING UPPER LOW DROPS INTO THE CENTRAL
US TROF...DIGGING IT EVEN DEEPER. STRONG SHORT WAVE ROTATES AROUND
THE LOW AS IT MOVES EAST FRI AND SAT.
AT THE SFC...THERE MAY BE SOME LINGERING SHOWERS WED AS OCCLUDED
FRONT MOVES ACROSS THE AREA. HIGHS ABOVE NORMAL AS DRIER...BRIEFLY
WARMER AIR MASS MOVES IN. THE GULF LOW TRACK ON THE ECMWF HAS MOVED
FARTHER OFF THE COAST...CLOSER TO THE GFS AND GEM TRACKS. THIS
SHOULD HELP KEEP WED NITE DRY BEFORE THE NEXT SYSTEM APPROACHES.
LOWS ABOVE NORMAL.
AS THE UPPER LOW MOVES TOWARD THE AREA THU...A VERY COLD AIR MASS
MOVES INTO THE AREA. THE GEFS HAS H85 TEMPS 1 TO 1.5 STANDARD
DEVIATIONS BELOW NORMAL. ALONG WITH THE COLD IS LOW LEVEL MOISTURE
MOVING IN FROM THE NW. THIS SETS UP THE POTENTIAL FOR A NW FLOW
PRECIP EVENT FROM THU THRU FRI NITE. EVEN THOUGH THE H85 TEMPS
REMAIN BELOW FREEZING...THE SFC TEMPS RISE ABOVE FREEZING DURING THE
DAY. THEREFORE...HAVE PRECIP STARTING AS RAIN THU AFT...THEN
CHANGING TO RAIN THU NITE. THIS TREND CONTINUES FRIDAY AS SNOW
CHANGES TO RAIN DURING THE DAY...THEN BACK TO SNOW OVERNIGHT. SOME
RAIN COULD DEVELOP OUTSIDE OF THE MTNS THU AFTERNOON...BUT PRECIP
SHOULD REMAIN LIMITED TO THE NORMAL MTN LOCATIONS AFTER. KEPT POPS
AT SLIGHT CHC FOR NOW GIVEN THE MDL TENDENCY TO OVER FORECAST THE
PRECIP AND AMOUNT OF COLD AIR FOR THESE EVENTS IN THE MEDIUM RANGE.
IT IS WAY TOO EARLY TO KNOW IF ADVISORY LEVEL OR HIGHER SNOW AMOUNTS
WILL DEVELOP. HIGHS THU BELOW NORMAL WEST AND NEAR NORMAL EAST.
TEMPS THEN BELOW NORMAL THU NITE THRU FRI NITE.
HAVE FCST PRECIP ENDING FRI NITE...BUT IT COULD LINGER SATURDAY. DRY
FCST SAT NITE. TEMPS REMAIN BELOW NORMAL.
&&
.AVIATION /16Z SUNDAY THROUGH THURSDAY/...
AT KCLT AND ELSEWHERE...AFTER SOME MORNING VLIFR AT KHKY...MAINLY
VFR EXPECTED THRU THE BULK OF THE DAY. PRECIP JUST NOW ENTERING THE
CWFA. HOWEVER...RAIN IS VERY LIGHT AND ANY RESTRICTIONS ARE STILL
WELL TO THE WEST. LOW VFR EXPECTED BY AFTERNOON AS RAIN MOVES IN
FROM THE WEST. AFTER THE RAIN MOISTENS THE LOW LEVELS...EXPECT A
QUICK TRANSITION TO MVFR VSBY AND LOW MVFR CIGS. CIGS FALL TO IFR
DURING THE EVENING AS THE PRECIP CONTINUES. CANNOT RULE OUT IFR VSBY
AND LIFR CIGS AFTER MIDNIGHT...ESPECIALLY IF SOME HEAVIER RAIN
DEVELOPS. NLY WINDS BECOME NELY AND INCREASE IN SPEED THRU THE
MORNING. THESE WINDS CONTINUE OVERNIGHT. THE EXCEPTION IS KAVL WHERE
SLY WINDS DEVELOP THIS MORNING...THEN BECOME NLY DURING THE
AFTERNOON.
OUTLOOK...THE COLD AIR DAMMING WEDGE WILL PERSIST THROUGH MONDAY
NIGHT WITH WIDESPREAD IFR CONDITIONS. THE MODEL GUIDANCE SHOWS
IMPROVEMENT TUESDAY BUT MOST LIKELY AT BEST MVFR SHOULD BE EXPECTED
UNTIL WEDNESDAY.
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...RWH
NEAR TERM...MCAVOY
SHORT TERM...JAT
LONG TERM...RWH
AVIATION...BSH/RWH
000
FXUS62 KCHS 221529
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
1029 AM EST SUN NOV 22 2009
.SYNOPSIS...
AN AREA OF LOW PRES WILL TRACK ALONG THE GULF COAST STATES TODAY
THEN RE-DEVELOP OVER OUR ADJACENT ATLC WATERS TONIGHT. THE LOW
WILL THEN LIFT NE OFF THE CAROLINA COAST MON INTO TUE...AS HIGH
PRES REMAINS ENTRENCHED OVER COASTAL SOUTH CAROLINA AND GEORGIA. A
SERIES OF DRY COLD FRONTS WILL SHIFT THROUGH THE AREA FROM LATE
WEEK INTO THE UPCOMING WEEKEND AS HIGH PRES SLOWLY BUILDS IN FROM
THE W.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
THE UPPER LOW WAS SPINNING ITS WHEELS OVER SOUTHERN ALABAMA THIS
MORNING WHILE THE SURFACE LOW HAD PUSHED INTO THE EASTERN GULF OF
MEXICO. THE VORT MAX ASSOCIATED WITH THE UPPER LOW IS SLOWLY
PUSHING INTO CENTRAL GA TOWARD THE SC MIDLANDS. THE HEAVIEST AND
MOST WIDESPREAD PRECIPITATION HAS BEEN OCCURRING AHEAD OF THIS
FEATURE...MAINLY WEST OF OUR FORECAST AREA. MEANWHILE HIGH
PRESSURE REMAINS ENTRENCHED FROM THE MID-ATLANTIC REGION THROUGH
THE CAROLINAS INTO SOUTHERN GA. DESPITE THE INCREASE IN ISENTROPIC
ASCENT ABOVE THE HIGH PRESSURE WEDGE...A CONSIDERABLE DRY SLOT
OVER THE EASTERN HALF OF THE AREA HAS PREVENTED MUCH IN THE WAY OF
MEASURABLE RAINFALL. LATER THIS AFTERNOON WE SHOULD SEE THE
COASTAL TROUGH OFF THE SC COAST STRENGTHEN WHICH SHOULD IN TURN
IMPROVE RAIN CHANCES ACROSS THE NORTHEASTERN PORTIONS.
HOWEVER...UNTIL THAT OCCURS WE DO NOT EXPECT TO SEE MORE THAN
SCATTERED COVERAGE OF RAIN EAST OF I-95. WE PARED BACK POPS OVER
THE EASTERN HALF OF THE AREA FOR MUCH OF THE DAY ALTHOUGH AT LEAST
LIKELY POPS WILL PREVAIL EVERYWHERE EXCEPT COASTAL CHARLESTON
COUNTY.
THUNDERSTORM POTENTIAL STILL APPEARS VERY LOW BUT AN AREA OF
6-6.5C MID-LEVEL LAPSE RATES MOVING THROUGH THIS AFTERNOON WITH
THE STRONGEST DYNAMICS COULD SUPPORT AN ISOLATED TSTM IN SOUTHERN
AREAS. TEMP FORECAST STILL APPEARS ON TRACK WITH HIGHS REMAINING
IN THE 50S.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM MONDAY/...
SURFACE LOW PRES ALONG S ALABAMA AND THE FLORIDA PANHANDLE WILL
WEAKEN BY THIS EVENING...THEN REDEVELOP OFF THE COAST OF THE
GEORGIA/FLORIDA BORDER...THEN TRACK NE ALONG THE W WALL OF THE
GULF STREAM E OF CHARLESTON BY LATE TONIGHT. THIS KEEPS A SOLID
WEDGE PATTERN GOING FOR OUR AREA. TEMPERATURES SHOULD BE COOL AND
FAIRLY STEADY. A PINCHED GRADIENT SUPPORTING BREEZY CONDITIONS
ALONG THE SOUTH CAROLINA COAST SHOULD RELAX LATE TONIGHT AS THE
EJECTING LOW BUCKLES THE WEDGE NW OVER EASTERN SOUTH CAROLINA.
LOCATIONS SUCH AS CHARLESTON...ST. GEORGE AND MONCKS CORNER MAY
SEE THEIR MOST SIGNIFICANT RAINS BETWEEN DUSK AND MIDNIGHT AS THE
DYNAMICS TRAVERSE THE AREA. ISOLATED ELEVATED THUNDER POSSIBLE E
OF I-95 IN SOUTH CAROLINA DURING THE EVENING. LATER TONIGHT...MID
LEVEL DRYING STRIPS UPPER MOISTURE AND LEAVES SOUNDING PROFILES
SUPPORTIVE OF LIGHTER RAINS AND DRIZZLE AFTER MIDNIGHT...ESPECIALLY
OVER SE GEORGIA WHERE PRECIP MAY JUST BE DRIZZLE LATE. NEAR COASTAL
BREEZES SHOULD ALSO SUBSIDE LATE AS THE PRES GRADIENT WEAKENS.
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
GUIDANCE IS IN GOOD AGREEMENT TRACKING SURFACE LOW PRESSURE
NORTHEASTWARD OFF THE CAROLINA COAST MONDAY THROUGH TUESDAY...WITH
NORTHERLY FLOW STRENGTHENING THE HIGH PRESSURE WEDGE ACROSS THE
FORECAST AREA. DEEP MOISTURE WILL HAVE SHIFTED OUT OF THE REGION BY
DAYBREAK MONDAY...BUT MODEL RELATIVE HUMIDITY TIME/HEIGHT CROSS
SECTIONS CONTINUE TO INDICATE A NEARLY SATURATED BOUNDARY LAYER
ACROSS THE ENTIRE FORECAST AREA THROUGH TUESDAY. GIVEN THE VERY
LIGHT WIND FIELDS OUT OF A NORTH-NORTHEAST THROUGH NORTH-NORTHWEST
DIRECTION AND THE LOW SUN ANGLE...EXPECT THE LOW LEVEL INVERSION TO
HOLD STRONG ACROSS THE AREA...RESULTING IN CLOUDY/MOSTLY CLOUDY
CONDITIONS ALONG WITH SOME LIGHT RAIN AND/OR AREAS OF DRIZZLE
IMPACTING THE REGION THROUGH TUESDAY.
MODEL SOLUTIONS ARE FOR THE MOST PART IN AGREEMENT FOR THE MID-LATE
WEEK TIME FRAME. THE EXCEPTION TO THIS IS THE ECMWF WHICH CONTINUES
TO ADVERTISE DEVELOPMENT OF A WAVE OF LOW PRESSURE TRACKING
NORTHEASTWARD OFF THE GEORGIA AND CAROLINA COAST WEDNESDAY NIGHT AND
THANKSGIVING DAY. GIVEN THE STRONG MODEL CONSENSUS OF THE
GFS/CANADIAN/UKMET SOLUTIONS...AS WELL AS THE ECMWF TRENDING TOWARD
THE SOLUTION OF THE OTHER OPERATIONAL MODELS...WILL KEEP THE
FORECAST RAIN FREE WEDNESDAY THROUGH THANKSGIVING DAY.
HIGH PRESSURE IS THEN EXPECTED TO BUILD BACK INTO THE AREA THURSDAY
NIGHT AND REMAIN THE DOMINANT WEATHER FEATURE THROUGH
SATURDAY...WITH RAIN FREE CONDITIONS ANTICIPATED ACROSS THE REGION.
&&
.AVIATION /15Z SUNDAY THROUGH THURSDAY/...
DETERIORATING CONDITIONS ON TAP TODAY...INITIALLY AT KSAV WHERE IFR
CIGS AND OCNL IFR VSBYS IN MODERATE RAINS ARE EXPECTED BY LATE
MORNING. AT KCHS...A SOMEWHAT DRIER LOW LEVEL AIR MASS MAY TAKE
AT BIT LONGER TO SATURATE THIS AFTERNOON. WE CONTINUED THE
PREVIOUS TREND OF INTRODUCING MVFR CIGS/VSBYS BY EARLY AFTERNOON
THEN IFR CONDITIONS LIKELY BY MID TO LATE AFTERNOON. NE SURFACE
WINDS WILL BE ON THE INCREASE AT BOTH TERMINALS TODAY AS THE PRES
GRADIENT TIGHTENS.
THIS EVENING INTO THE OVERNIGHT...RAINS WILL EVENTUALLY TAPER TO
DRIZZLE WITH POTENTIAL FOR LIFR CONDITIONS AT BOTH AIRPORTS AFTER
06Z/23. AT KSAV...MODELS ARE HITTING LOWER CIGS AND POSSIBLY
VSBYS 1/2 TO 1 MILE IN FOG AND DRIZZLE OVERNIGHT. KCHS SHOULD LOCK
IN WITH CIGS AT OR BELOW 500 FT AFTER MIDNIGHT BUT WITH WINDS
STAYING UP LONGER...VSBYS ARE NOT EXPECTED TO GET AS LOW AS KSAV.
EXTENDED AVIATION OUTLOOK...IFR CONDITIONS ARE LIKELY MON INTO TUE.
VFR CONDITIONS MAY RETURN WED THROUGH THU.
&&
.MARINE...
WINDS AND SEAS CONTINUE TO INCREASE THIS MORNING AS THE SURFACE WEDGE
DIGS IN FROM THE N AND PRES FALLS INCREASE OVER THE NE GULF OF MEXICO
AND N FLORIDA. WE HAVE RAISED SMALL CRAFT ADVISORIES FOR ALL
WATERS INCLUDING THE CHARLESTON HARBOR TODAY. A PINCHED GRADIENT
WILL GRADUALLY TILT NW INTO COASTAL SOUTH CAROLINA LATE TODAY AND
THIS EVENING...WITH NE WINDS BUILDING TO 20 TO 25 KT...LOCALLY
GUSTIER CONDITIONS POSSIBLE. IN SE GEORGIA...WINDS REACHING NEAR
20 KT AT THE SAVANNAH RIVER ENTRANCE AND POSSIBLY A BIT FURTHER S
SUGGEST SEAS AT LEAST 4-6 FT TODAY.
A WAVE OF LOW PRESSURE WILL TRACK NORTHEAST OFF THE CAROLINA
COAST MONDAY THROUGH TUESDAY...AS SURFACE HIGH PRESSURE REMAINS
STATIONARY OVER SOUTH CAROLINA AND GEORGIA AS WELL AS THE
NEARSHORE COASTAL WATERS. A WEAK COLD FRONT WILL THEN SHIFT
THROUGH THE WATERS WEDNESDAY NIGHT...WITH HIGH PRESSURE THEN
BUILDING BACK INTO THE AREA FOR THURSDAY.
COULD SEE SOME LINGERING SMALL CRAFT CONDITIONS THROUGH MONDAY
MORNING DUE TO ELEVATED SEAS OVER THE NORTHERN SOUTH CAROLINA
NEARSHORE WATERS AND THE OFFSHORE GEORGIA WATERS.
THEREFORE...EXTENDED THE SMALL CRAFT ADVISORY FOR THESE MARINE ZONES
THROUGH LATE MONDAY MORNING. ELSEWHERE...WINDS AND SEAS ARE EXPECTED
TO REMAIN BELOW SMALL CRAFT THRESHOLDS THROUGH THURSDAY.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR AMZ330-352-
354.
SMALL CRAFT ADVISORY UNTIL 11 AM EST MONDAY FOR AMZ350-374.
&&
$$
JRL
000
FXUS62 KCAE 221501 AAA
AFDCAE
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE COLUMBIA SC
1001 AM EST SUN NOV 22 2009
.SYNOPSIS...
A LOW PRESSURE SYSTEM ALONG THE GULF COAST REGION WILL MOVE SLOWLY
NORTHEAST ACROSS THE FLORIDA PANHANDLE TODAY THEN REFORM ALONG THE
CAROLINA COAST TONIGHT. HIGH PRESSURE WILL WEDGE INTO THE
CAROLINAS FROM THE NORTH. THIS PATTERN WILL BRING CLOUDS AND RAIN
TO THE AREA THROUGH MONDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A DEEP UPPER LOW CONTINUES TO LIFT NORTHEAST ACROSS MISSISSIPPI
THIS MORNING WHILE STRONG HIGH PRESSURE AT THE SURFACE STRENGTHENS
AS IT RIDGES DOWN THE EAST COAST. MOISTURE FLUX AND WARM ADVECTION
ARE MAXIMIZED EAST OF THE UPPER LOW AND RESULTING IN A BAND OF
RAIN EXTENDING FROM NORTH GEORGIA SOUTHEASTWARD TOWARDS SAVANNAH.
THIS BAND OF RAIN WILL CONTINUE LIFTING NORTH THROUGH THE LATE
MORNING AND EARLY AFTERNOON HOURS...SPREADING RAIN ACROSS THE
FORECAST AREA.
TEMPERATURES WILL STRUGGLE TO RISE MUCH TODAY WITH CONTINUED
NORTHEASTERLY FLOW AND PRECIPITATION MOVING OVER THE AREA...WHICH
WILL ENHANCE A DEVELOPING COLD AIR DAMMING WEDGE THAT IS
DEVELOPING. IT IS DIFFICULT TO FIGURE OUT HOW MUCH MORE
PRECIPITATION WILL DEVELOP BEHIND THIS INITIAL BAND AS THERE WILL
BE SOME DYNAMICS AVAILABLE AS THE LOW LIFTS OUT BUT A SIGNIFICANT
DRY AIR INTRUSION IS WRAPPING UNDERNEATH THE UPPER LOW AND PUSHING
ITS WAY INTO CENTRAL GEORGIA AT THIS TIME AND WILL MOVE INTO THE
FORECAST AREA BY LATE AFTERNOON. THIS LACK OF MOISTURE IN THE MID
AND UPPER LEVELS WILL LIKELY DECREASE THE CHANCE OF SIGNIFICANT
RAINFALL ACCUMULATION LATE AFTERNOON AND OVERNIGHT BUT LIGHT
SHOWERS WILL LINGER AND DRIZZLE SHOULD DEVELOP OVERNIGHT. CLOUDS
WILL REMAIN THROUGH THE DAY AS CEILINGS GRADUALLY LOWER AS THE
ATMOSPHERE MOISTENS UP.
MADE SOME CHANGES TO THE POP GRIDS TO ACCOUNT FOR SLIGHTLY FASTER
TIMING IN THE WARM ADVECTION BUT THE OVERALL CHANGE IN THE
FORECAST IS NOT GOING TO BE VERY SIGNIFICANT. WILL UPDATE THE ZONE
FORECAST TO REMOVE MORNING WORDING.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/...
WEAKENING SHORT WAVE WILL CROSS GEORGIA INTO THE CAROLINAS
TONIGHT. LOW PRESSURE DEVELOPING ON AN INVERTED TROUGH OFF THE SC
COAST. KEPT CATEGORICAL POPS THROUGH EARLY TONIGHT THEN
DIMINISHING AS ISENTROPIC LIFT SHIFTS NORTH AND WEST. RAINFALL
AMOUNTS RANGING FROM ONE HALF INCH TO AROUND ONE INCH. THE SURFACE
LOW WILL MOVE AWAY FROM THE COAST MONDAY WITH RAIN CHANCES
DECREASING. KEPT CHANCE OF DRIZZLE IN FOR MONDAY NIGHT INTO
TUESDAY WITH WEDGE POSSIBLY HOLDING AND HIGH LOW-LEVEL MOISTURE
SUGGESTED BY MODEL T-SECTIONS. COOLER THAN MOS GUIDANCE MAXIMUM
TEMPERATURE FORECAST DUE TO WEDGE.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
MEDIUM RANGE MODELS DEPICT A SERIES OF MID/UPPER LEVEL LOWS MOVING
ACROSS THE UPPER MIDWEST TO THE EASTERN GREAT LAKES AND
SOUTHEASTERN CANADA TUESDAY NIGHT INTO SATURDAY. ALL IN ALL,
SLIGHT UPPER RIDGING OVER THE SOUTHEAST PART OF THE COUNTRY
TUESDAY IS REPLACED BY A LARGE UPPER TROUGH OVER THE EASTERN
UNITED STATES WEDNESDAY THROUGH FRIDAY. UPPER TROUGH FINALLY MOVES
OFF THE EAST COAST SATURDAY. SURFACE HIGH PRESSURE CENTERED OVER
SOUTHEASTERN CANADA TUESDAY NIGHT RIDGING INTO THE AREA FROM THE
NORTH. SURFACE LOW PRESSURE CROSSING THE GREAT LAKES REGION ON
THANKSGIVING DAY WILL DRAG A COLD FRONT ACROSS THE AREA. MOISTURE
APPEARS LIMITED SINCE THE BEST ISENTROPIC LIFT REMAINS SOUTH AND
EAST OF THE FORECAST AREA. ANY CHANCE FOR RAIN (WHICH IS SLIGHT)
LOOKS LIKE WEDNESDAY INTO THURSDAY MORNING. COOL HIGH PRESSURE
BUILDS IN FOR FRIDAY AND SATURDAY. WILL KEEP THE EXTENDED FORECAST
DRY. SEASONABLY MILD MAX TEMPERATURES WEDNESDAY AND THURSDAY COOL
A FEW DEGREES BELOW NORMAL FOR FRIDAY AND SATURDAY. NIGHTTIME LOWS
IN THE 40S MID-WEEK COOLING TO THE MID AND UPPER 30S BY LATE NEXT
WEEK.
&&
.AVIATION /15Z SUNDAY THROUGH THURSDAY/...
HIGH PRESSURE OVER THE MID-ATLANTIC STATES AND NEW ENGLAND WILL
MOVE SLOWLY OFFSHORE THROUGH MONDAY. AN AREA OF LOW LOW PRESSURE
ALONG THE GULF OF MEXICO WILL WEAKEN AS IT MOVES NORTHEAST TOWARD
THE REGION. 88D REGIONAL COMPOSITE SHOWS A LARGE AREA OF
LIGHT/MODERATE RAIN STRETCHING FROM ALABAMA ACROSS GEORGIA. THE
NORTHERN EDGE WAS ALONG THE CSRA THIS MORNING. AS THE AREA OF LOW
PRESSURE GRADUALLY MOVES NE...EXPECT THE SHIELD OF PCPN TO
GRADUALLY MOVE INTO THE REGION THROUGH THE MORNING HOURS.
CURRENTLY ALL TAF SITES INDICATING VFR CONDITIONS...BUT CONDITIONS
WILL GRADUALLY DIMINISH THROUGH THE MORNING HOURS AND EXPECT MVFR
CONDITIONS TO DEVELOP BETWEEN 17-18Z. TIME SECTIONS SHOW ABUNDANT
LOW LEVEL MOISTURE THROUGH THE PERIOD ALONG WITH INCREASING
ISENTROPIC LIFT THIS AFTERNOON AND LASTING INTO MONDAY. EXPECT
CONDITIONS TO BECOME IFR/LIFR THIS EVENING AND REMAIN THROUGH THE
REST OF THE PERIOD...MAINLY DUE TO LOW CIGS. EXPECT RAIN THROUGH
THE DAY TO TAPER OFF TO DRIZZLE AND CONTINUE THROUGH THE PERIOD.
EXTENDED AVIATION OUTLOOK...WIDESPREAD MVFR OR IFR CONDITIONS WILL
CONTINUE MONDAY AND MONDAY NIGHT AND PERHAPS EVEN INTO TUESDAY. LOW
PRESSURE IS EXPECTED TO WEAKEN AS IT MOVES TOWARD THE AREA...THEN
REFORM ALONG THE NC/VA COAST. HOWEVER...HIGH PRESSURE IS EXPECTED TO
CONTINUE WEDGED IN ACRS THE REGION INTO TUESDAY...CONDITIONS SHOULD
IMPROVE TO VFR BY LATE TUESDAY.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
NEAR TERM...HC
000
FXUS62 KCAE 221151
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
651 AM EST SUN NOV 22 2009
.SYNOPSIS...
A LOW PRESSURE SYSTEM ALONG THE GULF COAST REGION WILL MOVE SLOWLY
NORTHEAST ACROSS THE FLORIDA PANHANDLE TODAY THEN REFORM ALONG THE
CAROLINA COAST TONIGHT. HIGH PRESSURE WILL WEDGE INTO THE
CAROLINAS FROM THE NORTH. THIS PATTERN WILL BRING CLOUDS AND RAIN
TO THE AREA THROUGH MONDAY.
&&
.NEAR TERM /THROUGH TODAY/...
SURFACE LOW AT 07Z OVER LOUISIANA MOVING SLOWLY NORTHEAST TODAY.
RADAR AT 07Z SHOWING RAIN MOVING INTO WESTERN GEORGIA. HIGH
PRESSURE OVER THE MID ATLANTIC/NORTHEASTERN STATES EXTENDING INTO
THE CAROLINAS. COLD AIR DAMMING WEDGE DEVELOPING. MODELS IN
AGREEMENT WITH STRONG ISENTROPIC LIFT/MOISTURE FLUX OVER THE AREA
THIS AFTERNOON. TEMPERATURES COOLER THAN PREVIOUS FORECAST AT 06Z
WITH MID TO HIGH LEVEL CLOUDS ADVECTING INTO THE AREA. CUT MAXIMUM
TEMPERATURES SLIGHTLY DUE TO COOLER START TO THE DAY/WEDGE
SCHEME...OTHERWISE VERY LITTLE CHANGES MADE. CATEGORICAL POPS
DEVELOPING FROM CSRA MID MORNING TO NORTHERN MIDLANDS THIS AFTERNOON.
&&
.SHORT TERM /TONIGHT THROUGH TUESDAY/...
WEAKENING SHORT WAVE WILL CROSS GEORGIA INTO THE CAROLINAS
TONIGHT. LOW PRESSURE DEVELOPING ON AN INVERTED TROUGH OFF THE SC
COAST. KEPT CATEGORICAL POPS THROUGH EARLY TONIGHT THEN
DIMINISHING AS ISENTROPIC LIFT SHIFTS NORTH AND WEST. RAINFALL
AMOUNTS RANGING FROM ONE HALF INCH TO AROUND ONE INCH. THE SURFACE
LOW WILL MOVE AWAY FROM THE COAST MONDAY WITH RAIN CHANCES
DECREASING. KEPT CHANCE OF DRIZZLE IN FOR MONDAY NIGHT INTO
TUESDAY WITH WEDGE POSSIBLY HOLDING AND HIGH LOW-LEVEL MOISTURE
SUGGESTED BY MODEL T-SECTIONS. COOLER THAN MOS GUIDANCE MAXIMUM
TEMPERATURE FORECAST DUE TO WEDGE.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
MEDIUM RANGE MODELS DEPICT A SERIES OF MID/UPPER LEVEL LOWS MOVING
ACROSS THE UPPER MIDWEST TO THE EASTERN GREAT LAKES AND
SOUTHEASTERN CANADA TUESDAY NIGHT INTO SATURDAY. ALL IN ALL,
SLIGHT UPPER RIDGING OVER THE SOUTHEAST PART OF THE COUNTRY
TUESDAY IS REPLACED BY A LARGE UPPER TROUGH OVER THE EASTERN
UNITED STATES WEDNESDAY THROUGH FRIDAY. UPPER TROUGH FINALLY MOVES
OFF THE EAST COAST SATURDAY. SURFACE HIGH PRESSURE CENTERED OVER
SOUTHEASTERN CANADA TUESDAY NIGHT RIDGING INTO THE AREA FROM THE
NORTH. SURFACE LOW PRESSURE CROSSING THE GREAT LAKES REGION ON
THANKSGIVING DAY WILL DRAG A COLD FRONT ACROSS THE AREA. MOISTURE
APPEARS LIMITED SINCE THE BEST ISENTROPIC LIFT REMAINS SOUTH AND
EAST OF THE FORECAST AREA. ANY CHANCE FOR RAIN (WHICH IS SLIGHT)
LOOKS LIKE WEDNESDAY INTO THURSDAY MORNING. COOL HIGH PRESSURE
BUILDS IN FOR FRIDAY AND SATURDAY. WILL KEEP THE EXTENDED FORECAST
DRY. SEASONABLY MILD MAX TEMPERATURES WEDNESDAY AND THURSDAY COOL
A FEW DEGREES BELOW NORMAL FOR FRIDAY AND SATURDAY. NIGHTTIME LOWS
IN THE 40S MID-WEEK COOLING TO THE MID AND UPPER 30S BY LATE NEXT
WEEK.
&&
.AVIATION /12Z SUNDAY THROUGH FRIDAY/...
HIGH PRESSURE OVER THE MID-ATLANTIC STATES AND NEW ENGLAND WILL MOVE
SLOWLY OFFSHORE THROUGH MONDAY. AN AREA OF LOW LOW PRESSURE ALONG
THE GULF OF MEXICO WILL WEAKEN AS IT MOVES NORTHEAST TOWARD THE
REGION. 88D REGIONAL COMPOSITE SHOWS A LARGE AREA OF LIGHT/MODERATE
RAIN STRETCHING FROM ALABAMA ACROSS GEORGIA. THE NORTHERN EDGE WAS
ALONG THE CSRA THIS MORNING. AS THE AREA OF LOW PRESSURE GRADUALLY
MOVES NE...EXPECT THE SHIELD OF PCPN TO GRADUALLY MOVE INTO THE
REGION THROUGH THE MORNING HOURS. CURRENTLY ALL TAF SITES INDICATING
VFR CONDITIONS...BUT CONDITIONS WILL GRADUALLY DIMINISH THROUGH THE
MORNING HOURS AND EXPECT MVFR CONDITIONS TO DEVELOP BETWEEN 17-18Z.
TIME SECTIONS SHOW ABUNDANT LOW LEVEL MOISTURE THROUGH THE PERIOD
ALONG WITH INCREASING ISENTROPIC LIFT THIS AFTERNOON AND LASTING
INTO MONDAY. EXPECT CONDITIONS TO BECOME IFR/LIFR THIS EVENING AND
REMAIN THROUGH THE REST OF THE PERIOD...MAINLY DUE TO LOW CIGS.
EXPECT RAIN THROUGH THE DAY TO TAPER OFF TO DRIZZLE AND CONTINUE
THROUGH THE PERIOD.
EXTENDED AVIATION OUTLOOK...WIDESPREAD MVFR OR IFR CONDITIONS WILL
CONTINUE MONDAY AND MONDAY NIGHT AND PERHAPS EVEN INTO TUESDAY. LOW
PRESSURE IS EXPECTED TO WEAKEN AS IT MOVES TOWARD THE AREA...THEN
REFORM ALONG THE NC/VA COAST. HOWEVER...HIGH PRESSURE IS EXPECTED TO
CONTINUE WEDGED IN ACRS THE REGION INTO TUESDAY...CONDITIONS SHOULD
IMPROVE TO VFR BY LATE TUESDAY.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
000
FXUS62 KGSP 221143
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
643 AM EST SUN NOV 22 2009
.SYNOPSIS...
HIGH PRESSURE WILL REMAIN WEDGED IN OVER THE REGION AS A LOW
PRESSURE SYSTEM MOVES EAST ALONG THE GULF COAST...THEN NORTH ALONG
THE CAROLINA COAST TODAY THROUGH MONDAY. THE LOW IS EXPECTED TO
REACH THE NEW ENGLAND COAST BY TUESDAY AS WEAK HIGH PRESSURE REMAINS
OVER THE SOUTHEAST STATES. A WEAK COLD FRONT WILL MOVE THROUGH THE
THE AREA BY THE MIDDLE OF THE WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
REGIONAL RADAR TRENDS SHOW THE LEADING EDGE OF THE PRECIP SHIELD
BEGINNING TO SPREAD NORTHWARD ACROSS CENTRAL GA...THOUGH A MODEL
SOUNDING TAKEN FROM KAND SHOWS A VERY DRY ATMOSPHERE STRETCHING FROM
THE SURFACE UP TO AROUND THE H6 LEVEL. THIS DRY LAYER SHOULD KEEP
THE NORTHWARD EXTENT OF MEASURABLE PRECIP IN CHECK THROUGH DAYBREAK
THOUGH HIGH CLOUDS WILL CONTINUE TO STREAM IN FROM THE SW.
OVERALL...THE VARIOUS MODEL SOLUTIONS ARE IN PRETTY GOOD AGREEMENT
WITH THE ONSET OF PRECIP ACROSS THE FA IN THE MID TO LATE MORNING
TIME FRAME WITH A SW TO NE GRADIENT. ALOFT...THE MID AND UPPER LEVEL
SHORTWAVE WILL DAMPEN OUT ALONG ITS NE TRACK TODAY. THE INITIAL BURST
OF PRECIP...THAT IS SPREADING NORTHWARD NOW...IS LARGELY BEING
FORCED BY AN AREA OF LOW LEVEL ISENTROPIC LIFT AND MID/UPPER LEVEL
DIVERGENCE OUT AHEAD OF THE TROF AXIS. STILL EXPECT THE BULK OF
PRECIP DURING THE TODAY PERIOD TO FAVOR AREAS TO THE SOUTH AND EAST
ESPECIALLY AS A COASTAL FRONT TAKES SHAPE DURING THE AFTERNOON. THEN
DURING THE OVERNIGHT...MODELS ALL INDICATE AN AREA OF WIDESPREAD
LIGHT PRECIP DEVELOPING ACROSS THE HEART OF THE FA AS A SECONDARY
AREA OF ISENTROPIC LIFT ON THE 295K SURFACE MOVES ACROSS THE REGION.
THIS ALSO COINCIDES WITH WHEN THE DEEPEST MOISTURE SETTLES IN. WEDGE
WILL FIRMLY REMAIN ENTRENCHED AS WAA SPREADS OVER TOP OF THE COOL
DOME THROUGH 12Z MONDAY.
CONCERNING TEMPS...I HAVE TRENDED HIGHS DOWNWARD ESPECIALLY ACROSS
THE EAST WHERE SKIES HAVE REMAINED NEARLY CLEAR FOR MUCH OF THE
EVENING AND EARLY MORNING. THIS HAS ALLOWED CURRENT TEMPS TO COOL TO
A COUPLE OF DEGREES BELOW THE TREND INDICATED BY GUIDANCE.
THEREFORE...I BLENDED TEMPS TOWARD THE COOLER MAV WHICH RESULTS IN
LOW 50S ALONG THE I-77 CORRIDOR.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
AS OF 230 AM EST SUNDAY...SOUTHWEST UPPER FLOW IS EXPECTED OVER THE
SOUTHEAST ON MONDAY...WITH SHORTWAVES CROSSING THE SOUTHERN
APPALACHIANS EARLY AND LATE IN THE DAY. AN UPPER LOW CROSSES THE
CENTRAL PLAINS FROM MONDAY NIGHT THROUGH WEDNESDAY NIGHT.
A SURFACE RIDGE WILL REMAIN ALONG THE EAST COAST MONDAY AND
TUESDAY...WITH ISENTROPIC UPGLIDE OVER IT THROUGH MONDAY...
SUPPORTING EXTENSIVE CLOUD COVER AND HIGH POPS. BY MONDAY NIGHT THE
MODELS DISAGREE ON THE AMOUNT AND LOCATION OF LINGERING UPGLIDE
FLOW...BUT IN NO CASE IS ANYTHING MORE THAN WEAK DOWNGLIDE SHOWN.
CLOUD COVER WILL BE INCREASED MONDAY NIGHT AND TUESDAY...AS THE CASE
FOR SCOURING THE LOW LEVEL MOISTURE IS WEAK. SMALL POPS WILL BE
MAINTAINED ALONG THE BLUE RIDGE ESCARPMENT MONDAY EVENING...UNTIL
SURFACE WINDS BACK TO THE NORTH. SURFACE WINDS VEER TO NORTHEAST
TUESDAY...AND WITH A LIGHT UPSLOPE COMPONENT...SMALL POPS WILL BE
REINTRODUCED TO THE BLUE RIDGE. AS A SURFACE FRONT APPROACHES
TUESDAY NIGHT...THE MODELS SHOW MOIST SOUTHERLY UPSLOPE FLOW
DEVELOPING...SUPPORTING INCREASING CLOUD COVER AND POPS INCREASING
FROM THE WEST.
WITH COLD AIR DAMMING ONGOING MONDAY...A LOW DIURNAL TEMPERATURE
RANGE WILL BE CARRIED. CLOUD COVER SHOULD KEEP MINIMUM TEMPERATURES
UP MONDAY NIGHT. MAXIMUM TEMPERATURES TUESDAY WILL LEAN TOWARD
LINGERING CLOUD COVER...ALTHOUGH THEY ARE SUBSTANTIALLY WARMER THAN
MONDAY. MINIMUM TEMPERATURES TUESDAY NIGHT REMAIN ELEVATED AS
SOUTHERLY FLOW AN MORE CLOUDS ARE EXPECTED.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
AS OF 330 AM SUNDAY...MDLS SHOWING BETTER AGREEMENT DURING THE
MEDIUM RANGE THAN THE PAST COUPLE OF DAYS. THIS RESULTS IN INCREASED
FORECAST CONFIDENCE. HOWEVER...GIVEN THE POSSIBLE SOLN...WILL KEEP
THINGS LOW KEY FOR NOW. REINFORCING UPPER LOW DROPS INTO THE CENTRAL
US TROF...DIGGING IT EVEN DEEPER. STRONG SHORT WAVE ROTATES AROUND
THE LOW AS IT MOVES EAST FRI AND SAT.
AT THE SFC...THERE MAY BE SOME LINGERING SHOWERS WED AS OCCLUDED
FRONT MOVES ACROSS THE AREA. HIGHS ABOVE NORMAL AS DRIER...BRIEFLY
WARMER AIR MASS MOVES IN. THE GULF LOW TRACK ON THE ECMWF HAS MOVED
FARTHER OFF THE COAST...CLOSER TO THE GFS AND GEM TRACKS. THIS
SHOULD HELP KEEP WED NITE DRY BEFORE THE NEXT SYSTEM APPROACHES.
LOWS ABOVE NORMAL.
AS THE UPPER LOW MOVES TOWARD THE AREA THU...A VERY COLD AIR MASS
MOVES INTO THE AREA. THE GEFS HAS H85 TEMPS 1 TO 1.5 STANDARD
DEVIATIONS BELOW NORMAL. ALONG WITH THE COLD IS LOW LEVEL MOISTURE
MOVING IN FROM THE NW. THIS SETS UP THE POTENTIAL FOR A NW FLOW
PRECIP EVENT FROM THU THRU FRI NITE. EVEN THOUGH THE H85 TEMPS
REMAIN BELOW FREEZING...THE SFC TEMPS RISE ABOVE FREEZING DURING THE
DAY. THEREFORE...HAVE PRECIP STARTING AS RAIN THU AFT...THEN
CHANGING TO RAIN THU NITE. THIS TREND CONTINUES FRIDAY AS SNOW
CHANGES TO RAIN DURING THE DAY...THEN BACK TO SNOW OVERNIGHT. SOME
RAIN COULD DEVELOP OUTSIDE OF THE MTNS THU AFTERNOON...BUT PRECIP
SHOULD REMAIN LIMITED TO THE NORMAL MTN LOCATIONS AFTER. KEPT POPS
AT SLIGHT CHC FOR NOW GIVEN THE MDL TENDENCY TO OVER FORECAST THE
PRECIP AND AMOUNT OF COLD AIR FOR THESE EVENTS IN THE MEDIUM RANGE.
IT IS WAY TOO EARLY TO KNOW IF ADVISORY LEVEL OR HIGHER SNOW AMOUNTS
WILL DEVELOP. HIGHS THU BELOW NORMAL WEST AND NEAR NORMAL EAST.
TEMPS THEN BELOW NORMAL THU NITE THRU FRI NITE.
HAVE FCST PRECIP ENDING FRI NITE...BUT IT COULD LINGER SATURDAY. DRY
FCST SAT NITE. TEMPS REMAIN BELOW NORMAL.
&&
.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
AT KCLT AND ELSEWHERE...AFTER SOME MORNING VLIFR AT KHKY...MAINLY
VFR EXPECTED THRU THE BULK OF THE DAY. PRECIP JUST NOW ENTERING THE
CWFA. HOWEVER...RAIN IS VERY LIGHT AND ANY RESTRICTIONS ARE STILL
WELL TO THE WEST. LOW VFR EXPECTED BY AFTERNOON AS RAIN MOVES IN
FROM THE WEST. AFTER THE RAIN MOISTENS THE LOW LEVELS...EXPECT A
QUICK TRANSITION TO MVFR VSBY AND LOW MVFR CIGS. CIGS FALL TO IFR
DURING THE EVENING AS THE PRECIP CONTINUES. CANNOT RULE OUT IFR VSBY
AND LIFR CIGS AFTER MIDNIGHT...ESPECIALLY IF SOME HEAVIER RAIN
DEVELOPS. NLY WINDS BECOME NELY AND INCREASE IN SPEED THRU THE
MORNING. THESE WINDS CONTINUE OVERNIGHT. THE EXCEPTION IS KAVL WHERE
SLY WINDS DEVELOP THIS MORNING...THEN BECOME NLY DURING THE
AFTERNOON.
OUTLOOK...THE COLD AIR DAMMING WEDGE WILL PERSIST THROUGH MONDAY
NIGHT WITH WIDESPREAD IFR CONDITIONS. THE MODEL GUIDANCE SHOWS
IMPROVEMENT TUESDAY BUT MOST LIKELY AT BEST MVFR SHOULD BE EXPECTED
UNTIL WEDNESDAY.
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...RWH
NEAR TERM...BSH
SHORT TERM...JAT
LONG TERM...RWH
AVIATION...BSH/RWH
000
FXUS62 KCHS 221136
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
636 AM EST SUN NOV 22 2009
.SYNOPSIS...
AN AREA OF LOW PRES WILL TRACK ALONG THE GULF COAST STATES TODAY
THEN RE-DEVELOP OVER OUR ADJACENT ATLC WATERS TONIGHT. THE LOW
WILL THEN LIFT NE OFF THE CAROLINA COAST MON INTO TUE...AS HIGH
PRES REMAINS ENTRENCHED OVER COASTAL SOUTH CAROLINA AND GEORGIA. A
SERIES OF DRY COLD FRONTS WILL SHIFT THROUGH THE AREA FROM LATE
WEEK INTO THE UPCOMING WEEKEND AS HIGH PRES SLOWLY BUILDS IN FROM
THE W.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A COMPLEX UPPER AIR PATTERN E OF THE ROCKIES TO INITIALIZE THIS
MORNINGS PACKAGE. THE MAIN FEATURE WE ARE FOCUSED ON TODAY IS
THE LIFTING AND OPENING CUT-OFF MID LEVEL LOW PRES SYSTEM IN THE
LOWER MISSISSIPPI VALLEY REGION. AS THIS SYSTEM WEAKENS AND PULLS
INTO THE SOUTHERN APPALACHIANS LATE TODAY...INCREASING UPPER
DIFLUENCE AND MID LEVEL OMEGA IS FORECAST TO SPREAD OVER OUR
FORECAST AREA ENHANCING RAINFALL FROM SW TO NE WITH TIME. AT THE
SURFACE...ALL OF OUR REGION WILL REMAIN ENTRENCHED IN A WEDGE
PATTERN WHICH WILL STAY LOCKED BY INCREASING RAINFALL AND VARIOUS
EVAPORATIVE COOLING PROCESSES. WE LOWERED FORECAST TEMPERATURES
SEVERAL DEGREES AND EXPECT ALMOST ALL AREAS WILL STAY IN THE 50S
TODAY. MANY AREAS ALONG TO THE W OF I-95 COULD SEE 1/2 TO 1 INCH
RAINS WITH A STRIPE OF HEAVIER RAINS POSSIBLE SOMEWHERE THROUGH
INLAND AREAS BY DAY/S END. ELEVATED THUNDER IS CERTAINLY POSSIBLY
IN SE GEORGIA AND W OF I-95 IN SOUTH CAROLINA THIS AFTERNOON
SUPPORTED BY GOOD LAPSE RATES BETWEEN 700 MB AND 500 MB AND STRONG
QG-FORCING PROGS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM MONDAY/...
SURFACE LOW PRES ALONG S ALABAMA AND THE FLORIDA PANHANDLE WILL
WEAKEN BY THIS EVENING...THEN REDEVELOP OFF THE COAST OF THE
GEORGIA/FLORIDA BORDER...THEN TRACK NE ALONG THE W WALL OF THE
GULF STREAM E OF CHARLESTON BY LATE TONIGHT. THIS KEEPS A SOLID
WEDGE PATTERN GOING FOR OUR AREA. TEMPERATURES SHOULD BE COOL AND
FAIRLY STEADY. A PINCHED GRADIENT SUPPORTING BREEZY CONDITIONS
ALONG THE SOUTH CAROLINA COAST SHOULD RELAX LATE TONIGHT AS THE
EJECTING LOW BUCKLES THE WEDGE NW OVER EASTERN SOUTH CAROLINA.
LOCATIONS SUCH AS CHARLESTON...ST. GEORGE AND MONCKS CORNER MAY
SEE THEIR MOST SIGNIFICANT RAINS BETWEEN DUSK AND MIDNIGHT AS THE
DYNAMICS TRAVERSE THE AREA. ISOLATED ELEVATED THUNDER POSSIBLE E
OF I-95 IN SOUTH CAROLINA DURING THE EVENING. LATER TONIGHT...MID
LEVEL DRYING STRIPS UPPER MOISTURE AND LEAVES SOUNDING PROFILES
SUPPORTIVE OF LIGHTER RAINS AND DRIZZLE AFTER MIDNIGHT...ESPECIALLY
OVER SE GEORGIA WHERE PRECIP MAY JUST BE DRIZZLE LATE. NEAR COASTAL
BREEZES SHOULD ALSO SUBSIDE LATE AS THE PRES GRADIENT WEAKENS.
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
GUIDANCE IS IN GOOD AGREEMENT TRACKING SURFACE LOW PRESSURE
NORTHEASTWARD OFF THE CAROLINA COAST MONDAY THROUGH TUESDAY...WITH
NORTHERLY FLOW STRENGTHENING THE HIGH PRESSURE WEDGE ACROSS THE
FORECAST AREA. DEEP MOISTURE WILL HAVE SHIFTED OUT OF THE REGION BY
DAYBREAK MONDAY...BUT MODEL RELATIVE HUMIDITY TIME/HEIGHT CROSS
SECTIONS CONTINUE TO INDICATE A NEARLY SATURATED BOUNDARY LAYER
ACROSS THE ENTIRE FORECAST AREA THROUGH TUESDAY. GIVEN THE VERY
LIGHT WIND FIELDS OUT OF A NORTH-NORTHEAST THROUGH NORTH-NORTHWEST
DIRECTION AND THE LOW SUN ANGLE...EXPECT THE LOW LEVEL INVERSION TO
HOLD STRONG ACROSS THE AREA...RESULTING IN CLOUDY/MOSTLY CLOUDY
CONDITIONS ALONG WITH SOME LIGHT RAIN AND/OR AREAS OF DRIZZLE
IMPACTING THE REGION THROUGH TUESDAY.
MODEL SOLUTIONS ARE FOR THE MOST PART IN AGREEMENT FOR THE MID-LATE
WEEK TIME FRAME. THE EXCEPTION TO THIS IS THE ECMWF WHICH CONTINUES
TO ADVERTISE DEVELOPMENT OF A WAVE OF LOW PRESSURE TRACKING
NORTHEASTWARD OFF THE GEORGIA AND CAROLINA COAST WEDNESDAY NIGHT AND
THANKSGIVING DAY. GIVEN THE STRONG MODEL CONSENSUS OF THE
GFS/CANADIAN/UKMET SOLUTIONS...AS WELL AS THE ECMWF TRENDING TOWARD
THE SOLUTION OF THE OTHER OPERATIONAL MODELS...WILL KEEP THE
FORECAST RAIN FREE WEDNESDAY THROUGH THANKSGIVING DAY.
HIGH PRESSURE IS THEN EXPECTED TO BUILD BACK INTO THE AREA THURSDAY
NIGHT AND REMAIN THE DOMINANT WEATHER FEATURE THROUGH
SATURDAY...WITH RAIN FREE CONDITIONS ANTICIPATED ACROSS THE REGION.
&&
.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
DETERIORATING CONDITIONS ON TAP TODAY...INITIALLY AT KSAV WHERE IFR
CIGS AND OCNL IFR VSBYS IN MODERATE RAINS ARE EXPECTED BY LATE
MORNING. AT KCHS...A SOMEWHAT DRIER LOW LEVEL AIR MASS MAY TAKE
AT BIT LONGER TO SATURATE THIS AFTERNOON. WE CONTINUED THE
PREVIOUS TREND OF INTRODUCING MVFR CIGS/VSBYS BY EARLY AFTERNOON
THEN IFR CONDITIONS LIKELY BY MID TO LATE AFTERNOON. NE SURFACE
WINDS WILL BE ON THE INCREASE AT BOTH TERMINALS TODAY AS THE PRES
GRADIENT TIGHTENS.
THIS EVENING INTO THE OVERNIGHT...RAINS WILL EVENTUALLY TAPER TO
DRIZZLE WITH POTENTIAL FOR LIFR CONDITIONS AT BOTH AIRPORTS AFTER
06Z/23. AT KSAV...MODELS ARE HITTING LOWER CIGS AND POSSIBLY
VSBYS 1/2 TO 1 MILE IN FOG AND DRIZZLE OVERNIGHT. KCHS SHOULD LOCK
IN WITH CIGS AT OR BELOW 500 FT AFTER MIDNIGHT BUT WITH WINDS
STAYING UP LONGER...VSBYS ARE NOT EXPECTED TO GET AS LOW AS KSAV.
EXTENDED AVIATION OUTLOOK...IFR CONDITIONS ARE LIKELY MON INTO TUE.
VFR CONDITIONS MAY RETURN WED THROUGH THU.
&&
.MARINE...
WINDS AND SEAS CONTINUE TO INCREASE THIS MORNING AS THE SURFACE WEDGE
DIGS IN FROM THE N AND PRES FALLS INCREASE OVER THE NE GULF OF MEXICO
AND N FLORIDA. WE HAVE RAISED SMALL CRAFT ADVISORIES FOR ALL
WATERS INCLUDING THE CHARLESTON HARBOR TODAY. A PINCHED GRADIENT
WILL GRADUALLY TILT NW INTO COASTAL SOUTH CAROLINA LATE TODAY AND
THIS EVENING...WITH NE WINDS BUILDING TO 20 TO 25 KT...LOCALLY
GUSTIER CONDITIONS POSSIBLE. IN SE GEORGIA...WINDS REACHING NEAR
20 KT AT THE SAVANNAH RIVER ENTRANCE AND POSSIBLY A BIT FURTHER S
SUGGEST SEAS AT LEAST 4-6 FT TODAY.
A WAVE OF LOW PRESSURE WILL TRACK NORTHEAST OFF THE CAROLINA
COAST MONDAY THROUGH TUESDAY...AS SURFACE HIGH PRESSURE REMAINS
STATIONARY OVER SOUTH CAROLINA AND GEORGIA AS WELL AS THE
NEARSHORE COASTAL WATERS. A WEAK COLD FRONT WILL THEN SHIFT
THROUGH THE WATERS WEDNESDAY NIGHT...WITH HIGH PRESSURE THEN
BUILDING BACK INTO THE AREA FOR THURSDAY.
COULD SEE SOME LINGERING SMALL CRAFT CONDITIONS THROUGH MONDAY
MORNING DUE TO ELEVATED SEAS OVER THE NORTHERN SOUTH CAROLINA
NEARSHORE WATERS AND THE OFFSHORE GEORGIA WATERS.
THEREFORE...EXTENDED THE SMALL CRAFT ADVISORY FOR THESE MARINE ZONES
THROUGH LATE MONDAY MORNING. ELSEWHERE...WINDS AND SEAS ARE EXPECTED
TO REMAIN BELOW SMALL CRAFT THRESHOLDS THROUGH THURSDAY.
&&
.TIDES/COASTAL FLOODING...
TIDAL DEPARTURES HAVE BEEN ON THE INCREASE OVERNIGHT AND ARE BECOMING
MORE OF A CONCERN FOR POSSIBLE MINOR SHALLOW COASTAL FLOODING ALONG
THE SOUTH CAROLINA LATER THIS MORNING. IF RECENT TRENDS CONTINUE...WE
MAY NEED TO ISSUE A COASTAL FLOOD ADVISORY FOR TIDES NEARING 7 FT MLLW
IN DOWNTOWN CHARLESTON FOR THE MIDDAY HIGH TIDE. CERTAINLY ANY RAINFALL
WOULD EXACERBATE THE PROBLEM. WE HAVE HIGHLIGHTED POTENTIAL IN OUR HWO.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 10 AM THIS MORNING TO MIDNIGHT EST
TONIGHT FOR AMZ330.
SMALL CRAFT ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR AMZ352-354.
SMALL CRAFT ADVISORY UNTIL 11 AM EST MONDAY FOR AMZ350-374.
&&
$$
000
FXUS62 KCHS 220919
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
419 AM EST SUN NOV 22 2009
.SYNOPSIS...
AN AREA OF LOW PRES WILL TRACK ALONG THE GULF COAST STATES TODAY
THEN RE-DEVELOP OVER OUR ADJACENT ATLC WATERS TONIGHT. THE LOW
WILL THEN LIFT NE OFF THE CAROLINA COAST MON INTO TUE...AS HIGH
PRES REMAINS ENTRENCHED OVER COASTAL SOUTH CAROLINA AND GEORGIA. A
SERIES OF DRY COLD FRONTS WILL SHIFT THROUGH THE AREA FROM LATE
WEEK INTO THE UPCOMING WEEKEND AS HIGH PRES SLOWLY BUILDS IN FROM
THE W.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A COMPLEX UPPER AIR PATTERN E OF THE ROCKIES TO INITIALIZE THIS
MORNINGS PACKAGE. THE MAIN FEATURE WE ARE FOCUSED ON TODAY IS
THE LIFTING AND OPENING CUT-OFF MID LEVEL LOW PRES SYSTEM IN THE
LOWER MISSISSIPPI VALLEY REGION. AS THIS SYSTEM WEAKENS AND PULLS
INTO THE SOUTHERN APPALACHIANS LATE TODAY...INCREASING UPPER
DIFLUENCE AND MID LEVEL OMEGA IS FORECAST TO SPREAD OVER OUR
FORECAST AREA ENHANCING RAINFALL FROM SW TO NE WITH TIME. AT THE
SURFACE...ALL OF OUR REGION WILL REMAIN ENTRENCHED IN A WEDGE
PATTERN WHICH WILL STAY LOCKED BY INCREASING RAINFALL AND VARIOUS
EVAPORATIVE COOLING PROCESSES. WE LOWERED FORECAST TEMPERATURES
SEVERAL DEGREES AND EXPECT ALMOST ALL AREAS WILL STAY IN THE 50S
TODAY. MANY AREAS ALONG TO THE W OF I-95 COULD SEE 1/2 TO 1 INCH
RAINS WITH A STRIPE OF HEAVIER RAINS POSSIBLE SOMEWHERE THROUGH
INLAND AREAS BY DAY/S END. ELEVATED THUNDER IS CERTAINLY POSSIBLY
IN SE GEORGIA AND W OF I-95 IN SOUTH CAROLINA THIS AFTERNOON
SUPPORTED BY GOOD LAPSE RATES BETWEEN 700 MB AND 500 MB AND STRONG
Q-FORCING PROGS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM MONDAY/...
SURFACE LOW PRES ALONG S ALABAMA AND THE FLORIDA PANHANDLE WILL
WEAKEN BY THIS EVENING...THEN REDEVELOP OFF THE COAST OF THE
GEORGIA/FLORIDA BORDER...THEN TRACK NE ALONG THE W WALL OF THE
GULF STREAM E OF CHARLESTON BY LATE TONIGHT. THIS KEEPS A SOLID
WEDGE PATTERN GOING FOR OUR AREA. TEMPERATURES SHOULD BE COOL AND
FAIRLY STEADY. A PINCHED GRADIENT SUPPORTING BREEZY CONDITIONS
ALONG THE SOUTH CAROLINA COAST SHOULD RELAX LATE TONIGHT AS THE
EJECTING LOW BUCKLES THE WEDGE NW OVER EASTERN SOUTH CAROLINA.
LOCATIONS SUCH AS CHARLESTON...ST. GEORGE AND MONCKS CORNER MAY
SEE THEIR MOST SIGNIFICANT RAINS BETWEEN DUSK AND MIDNIGHT AS THE
DYNAMICS TRAVERSE THE AREA. ISOLATED ELEVATED THUNDER POSSIBLE E
OF I-95 IN SOUTH CAROLINA DURING THE EVENING. LATER TONIGHT...MID
LEVEL DRYING STRIPS UPPER MOISTURE AND LEAVES SOUNDING PROFILES
SUPPORTIVE OF LIGHTER RAINS AND DRIZZLE AFTER MIDNIGHT...ESPECIALLY
OVER SE GEORGIA WHERE PRECIP MAY JUST BE DRIZZLE LATE. NEAR COASTAL
BREEZES SHOULD ALSO SUBSIDE LATE AS THE PRES GRADIENT WEAKENS.
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
GUIDANCE IS IN GOOD AGREEMENT TRACKING SURFACE LOW PRESSURE
NORTHEASTWARD OFF THE CAROLINA COAST MONDAY THROUGH TUESDAY...WITH
NORTHERLY FLOW STRENGTHENING THE HIGH PRESSURE WEDGE ACROSS THE
FORECAST AREA. DEEP MOISTURE WILL HAVE SHIFTED OUT OF THE REGION BY
DAYBREAK MONDAY...BUT MODEL RELATIVE HUMIDITY TIME/HEIGHT CROSS
SECTIONS CONTINUE TO INDICATE A NEARLY SATURATED BOUNDARY LAYER
ACROSS THE ENTIRE FORECAST AREA THROUGH TUESDAY. GIVEN THE VERY
LIGHT WIND FIELDS OUT OF A NORTH-NORTHEAST THROUGH NORTH-NORTHWEST
DIRECTION AND THE LOW SUN ANGLE...EXPECT THE LOW LEVEL INVERSION TO
HOLD STRONG ACROSS THE AREA...RESULTING IN CLOUDY/MOSTLY CLOUDY
CONDITIONS ALONG WITH SOME LIGHT RAIN AND/OR AREAS OF DRIZZLE
IMPACTING THE REGION THROUGH TUESDAY.
MODEL SOLUTIONS ARE FOR THE MOST PART IN AGREEMENT FOR THE MID-LATE
WEEK TIME FRAME. THE EXCEPTION TO THIS IS THE ECMWF WHICH CONTINUES
TO ADVERTISE DEVELOPMENT OF A WAVE OF LOW PRESSURE TRACKING
NORTHEASTWARD OFF THE GEORGIA AND CAROLINA COAST WEDNESDAY NIGHT AND
THANKSGIVING DAY. GIVEN THE STRONG MODEL CONSENSUS OF THE
GFS/CANADIAN/UKMET SOLUTIONS...AS WELL AS THE ECMWF TRENDING TOWARD
THE SOLUTION OF THE OTHER OPERATIONAL MODELS...WILL KEEP THE
FORECAST RAIN FREE WEDNESDAY THROUGH THANKSGIVING DAY.
HIGH PRESSURE IS THEN EXPECTED TO BUILD BACK INTO THE AREA THURSDAY
NIGHT AND REMAIN THE DOMINANT WEATHER FEATURE THROUGH
SATURDAY...WITH RAIN FREE CONDITIONS ANTICIPATED ACROSS THE REGION.
&&
.AVIATION /09Z SUNDAY THROUGH THURSDAY/...
KCHS...HIGH PRES WEDGE HOLDS IN PLACE TONIGHT WITH ANTICYCLONIC
FLOW...AND ONLY LIMITED MOISTURE TO BE FOUND IN PLACE. THUS WE
HAVE MAINTAINED VFR WEATHER THROUGH THE MORNING HOURS. HOWEVER...
SHORT WAVE NOW MOVING INTO THE NE GULF OF MEXICO WILL MOVE
THROUGH AFTER DAYBREAK AND RESULT IN SOME LIGHT RAINS DEVELOPING
AROUND 15Z...AND ALSO FOR A LOWERING OF THE CIGS TO AROUND 5K
FEET. THE COMBINATION OF INCREASING LOW LEVEL CONVERGENCE...
ISENTROPIC LIFT AND SHORT WAVES ALOFT WILL PRODUCE A HEAVIER AND
STEADIER RAIN OVERSPREADING THE AREA DURING THE AFTERNOON...AND
WITH IT OUR CONDITIONS WILL DROP TO MVFR AT 18Z AND TO IFR AT 21Z.
NE WINDS SHOULD BEGIN TO GUST OVER 15 KT LATE IN THE AFTERNOON AND
WE EXPECTED A DECENT POTENTIAL FOR SURFACE FLOW GUSTING INTO THE
15 TO 20 KT RANGE TOWARD THE END OF TAF CYCLE. IFR CIGS AND VSBYS
INTO THE LATTER 6 HOURS OF THE TAF CYCLE WITH RAINFALL ANTICIPATED
AND POSSIBLY SOME GUSTY NE SURFACE WINDS AT TIMES.
KSAV...THE HIGH PRES WEDGE AND ITS RESULTING ANTICYCLONIC FLOW
EARLY TONIGHT WILL GIVE WAY TO A SHORT WAVE AND MORE CYCLONIC
CURVATURE OF THE ISOBARS LATE TONIGHT. THIS ALLOWS FOR A STEADY
MOISTENING OF THE LOWER LEVELS AND EVENTUALLY LIGHT RAINS AND A
LOWERING OF THE CIGS TO OCCUR...FALLING TO MVFR AT 14Z. A MORE
SUBSTANTIAL INCREASE IN OVERALL MOISTURE AND LOW LEVEL CONVERGENCE
AND ISENTROPIC LIFT FORMS FOR THE AFTERNOON...AND IFR WEATHER WILL
PREVAIL FROM 18Z ONWARDS. LATER SHIFTS WILL NEED TO KEEP WATCH FOR
A LITTLE ELEVATED CONVECTION THAT WILL ATTEMPT TO DEVELOP LATE
SUNDAY AS SHOWALTER INDICES DROP TO -1 OR -2 AND MID LEVEL LAPSE
RATES APPROACH 6C/KM. GIVEN THE WEDGE IN PLACE AND ATMOSPHERIC
DYNAMICS TAPPED BY THE MODELS WE INCREASING NE SURFACE WINDS INTO
THE 10-15 KT RANGE THIS AFTERNOON AND THERE COULD BE A FEW GUSTS
TO 20 KT AT TIMES. AFTER DUSK...RAIN IS EXPECTED TO TAPER TO
LIGHTER RAINS AND DRIZZLE WITH IFR/LIFR CIGS AND MVFR/IFR VSBYS.
EXTENDED AVIATION OUTLOOK...IFR CONDITIONS ARE LIKELY SUNDAY NIGHT
THROUGH TUE. VFR CONDITIONS MAY RETURN WED THROUGH THU.
&&
.MARINE...
WINDS AND SEAS CONTINUE TO INCREASE THIS MORNING AS THE SURFACE WEDGE
DIGS IN FROM THE N AND PRES FALLS INCREASE OVER THE NE GULF OF MEXICO
AND N FLORIDA. WE HAVE RAISED SMALL CRAFT ADVISORIES FOR ALL
WATERS INCLUDING THE CHARLESTON HARBOR TODAY. A PINCHED GRADIENT
WILL GRADUALLY TILT NW INTO COASTAL SOUTH CAROLINA LATE TODAY AND
THIS EVENING...WITH NE WINDS BUILDING TO 20 TO 25 KT...LOCALLY
GUSTIER CONDITIONS POSSIBLE. IN SE GEORGIA...WINDS REACHING NEAR
20 KT AT THE SAVANNAH RIVER ENTRANCE AND POSSIBLY A BIT FURTHER S
SUGGEST SEAS AT LEAST 4-6 FT TODAY.
A WAVE OF LOW PRESSURE WILL TRACK NORTHEAST OFF THE CAROLINA
COAST MONDAY THROUGH TUESDAY...AS SURFACE HIGH PRESSURE REMAINS
STATIONARY OVER SOUTH CAROLINA AND GEORGIA AS WELL AS THE
NEARSHORE COASTAL WATERS. A WEAK COLD FRONT WILL THEN SHIFT
THROUGH THE WATERS WEDNESDAY NIGHT...WITH HIGH PRESSURE THEN
BUILDING BACK INTO THE AREA FOR THURSDAY.
COULD SEE SOME LINGERING SMALL CRAFT CONDITIONS THROUGH MONDAY
MORNING DUE TO ELEVATED SEAS OVER THE NORTHERN SOUTH CAROLINA
NEARSHORE WATERS AND THE OFFSHORE GEORGIA WATERS.
THEREFORE...EXTENDED THE SMALL CRAFT ADVISORY FOR THESE MARINE ZONES
THROUGH LATE MONDAY MORNING. ELSEWHERE...WINDS AND SEAS ARE EXPECTED
TO REMAIN BELOW SMALL CRAFT THRESHOLDS THROUGH THURSDAY.
&&
.TIDES/COASTAL FLOODING...
TIDAL DEPARTURES HAVE BEEN ON THE INCREASE OVERNIGHT AND ARE BECOMING
MORE OF A CONCERN FOR POSSIBLE MINOR SHALLOW COASTAL FLOODING ALONG
THE SOUTH CAROLINA LATER THIS MORNING. IF RECENT TRENDS CONTINUE...WE
MAY NEED TO ISSUE A COASTAL FLOOD ADVISORY FOR TIDES NEARING 7 FT MLLW
IN DOWNTOWN CHARLESTON FOR THE MIDDAY HIGH TIDE. CERTAINLY ANY RAINFALL
WOULD EXACERBATE THE PROBLEM. WE HAVE HIGHLIGHTED POTENTIAL IN OUR HWO.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 10 AM THIS MORNING TO MIDNIGHT EST
TONIGHT FOR AMZ330.
SMALL CRAFT ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR AMZ352-354.
SMALL CRAFT ADVISORY UNTIL 11 AM EST MONDAY FOR AMZ350-374.
&&
$$
JRJ
000
FXUS62 KGSP 220835
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
335 AM EST SUN NOV 22 2009
.SYNOPSIS...
HIGH PRESSURE WILL REMAIN WEDGED IN OVER THE REGION AS A LOW
PRESSURE SYSTEM MOVES EAST ALONG THE GULF COAST...THEN NORTH ALONG
THE CAROLINA COAST TODAY THROUGH MONDAY. THE LOW IS EXPECTED TO
REACH THE NEW ENGLAND COAST BY TUESDAY AS WEAK HIGH PRESSURE REMAINS
OVER THE SOUTHEAST STATES. A WEAK COLD FRONT WILL MOVE THROUGH THE
THE AREA BY THE MIDDLE OF THE WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
REGIONAL RADAR TRENDS SHOW THE LEADING EDGE OF THE PRECIP SHIELD
BEGINNING TO SPREAD NORTHWARD ACROSS CENTRAL GA...THOUGH A MODEL
SOUNDING TAKEN FROM KAND SHOWS A VERY DRY ATMOSPHERE STRETCHING FROM
THE SURFACE UP TO AROUND THE H6 LEVEL. THIS DRY LAYER SHOULD KEEP
THE NORTHWARD EXTENT OF MEASURABLE PRECIP IN CHECK THROUGH DAYBREAK
THOUGH HIGH CLOUDS WILL CONTINUE TO STREAM IN FROM THE SW.
OVERALL...THE VARIOUS MODEL SOLUTIONS ARE IN PRETTY GOOD AGREEMENT
WITH THE ONSET OF PRECIP ACROSS THE FA IN THE MID TO LATE MORNING
TIME FRAME WITH A SW TO NE GRADIENT. ALOFT...THE MID AND UPPER LEVEL
SHORTWAVE WILL DAMPEN OUT ALONG ITS NE TRACK TODAY. THE INITIAL BURST
OF PRECIP...THAT IS SPREADING NORTHWARD NOW...IS LARGELY BEING
FORCED BY AN AREA OF LOW LEVEL ISENTROPIC LIFT AND MID/UPPER LEVEL
DIVERGENCE OUT AHEAD OF THE TROF AXIS. STILL EXPECT THE BULK OF
PRECIP DURING THE TODAY PERIOD TO FAVOR AREAS TO THE SOUTH AND EAST
ESPECIALLY AS A COASTAL FRONT TAKES SHAPE DURING THE AFTERNOON. THEN
DURING THE OVERNIGHT...MODELS ALL INDICATE AN AREA OF WIDESPREAD
LIGHT PRECIP DEVELOPING ACROSS THE HEART OF THE FA AS A SECONDARY
AREA OF ISENTROPIC LIFT ON THE 295K SURFACE MOVES ACROSS THE REGION.
THIS ALSO COINCIDES WITH WHEN THE DEEPEST MOISTURE SETTLES IN. WEDGE
WILL FIRMLY REMAIN ENTRENCHED AS WAA SPREADS OVER TOP OF THE COOL
DOME THROUGH 12Z MONDAY.
CONCERNING TEMPS...I HAVE TRENDED HIGHS DOWNWARD ESPECIALLY ACROSS
THE EAST WHERE SKIES HAVE REMAINED NEARLY CLEAR FOR MUCH OF THE
EVENING AND EARLY MORNING. THIS HAS ALLOWED CURRENT TEMPS TO COOL TO
A COUPLE OF DEGREES BELOW THE TREND INDICATED BY GUIDANCE.
THEREFORE...I BLENDED TEMPS TOWARD THE COOLER MAV WHICH RESULTS IN
LOW 50S ALONG THE I-77 CORRIDOR.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
AS OF 230 AM EST SUNDAY...SOUTHWEST UPPER FLOW IS EXPECTED OVER THE
SOUTHEAST ON MONDAY...WITH SHORTWAVES CROSSING THE SOUTHERN
APPALACHIANS EARLY AND LATE IN THE DAY. AN UPPER LOW CROSSES THE
CENTRAL PLAINS FROM MONDAY NIGHT THROUGH WEDNESDAY NIGHT.
A SURFACE RIDGE WILL REMAIN ALONG THE EAST COAST MONDAY AND
TUESDAY...WITH ISENTROPIC UPGLIDE OVER IT THROUGH MONDAY...
SUPPORTING EXTENSIVE CLOUD COVER AND HIGH POPS. BY MONDAY NIGHT THE
MODELS DISAGREE ON THE AMOUNT AND LOCATION OF LINGERING UPGLIDE
FLOW...BUT IN NO CASE IS ANYTHING MORE THAN WEAK DOWNGLIDE SHOWN.
CLOUD COVER WILL BE INCREASED MONDAY NIGHT AND TUESDAY...AS THE CASE
FOR SCOURING THE LOW LEVEL MOISTURE IS WEAK. SMALL POPS WILL BE
MAINTAINED ALONG THE BLUE RIDGE ESCARPMENT MONDAY EVENING...UNTIL
SURFACE WINDS BACK TO THE NORTH. SURFACE WINDS VEER TO NORTHEAST
TUESDAY...AND WITH A LIGHT UPSLOPE COMPONENT...SMALL POPS WILL BE
REINTRODUCED TO THE BLUE RIDGE. AS A SURFACE FRONT APPROACHES
TUESDAY NIGHT...THE MODELS SHOW MOIST SOUTHERLY UPSLOPE FLOW
DEVELOPING...SUPPORTING INCREASING CLOUD COVER AND POPS INCREASING
FROM THE WEST.
WITH COLD AIR DAMMING ONGOING MONDAY...A LOW DIURNAL TEMPERATURE
RANGE WILL BE CARRIED. CLOUD COVER SHOULD KEEP MINIMUM TEMPERATURES
UP MONDAY NIGHT. MAXIMUM TEMPERATURES TUESDAY WILL LEAN TOWARD
LINGERING CLOUD COVER...ALTHOUGH THEY ARE SUBSTANTIALLY WARMER THAN
MONDAY. MINIMUM TEMPERATURES TUESDAY NIGHT REMAIN ELEVATED AS
SOUTHERLY FLOW AN MORE CLOUDS ARE EXPECTED.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
AS OF 330 AM SUNDAY...MDLS SHOWING BETTER AGREEMENT DURING THE
MEDIUM RANGE THAN THE PAST COUPLE OF DAYS. THIS RESULTS IN INCREASED
FORECAST CONFIDENCE. HOWEVER...GIVEN THE POSSIBLE SOLN...WILL KEEP
THINGS LOW KEY FOR NOW. REINFORCING UPPER LOW DROPS INTO THE CENTRAL
US TROF...DIGGING IT EVEN DEEPER. STRONG SHORT WAVE ROTATES AROUND
THE LOW AS IT MOVES EAST FRI AND SAT.
AT THE SFC...THERE MAY BE SOME LINGERING SHOWERS WED AS OCCLUDED
FRONT MOVES ACROSS THE AREA. HIGHS ABOVE NORMAL AS DRIER...BRIEFLY
WARMER AIR MASS MOVES IN. THE GULF LOW TRACK ON THE ECMWF HAS MOVED
FARTHER OFF THE COAST...CLOSER TO THE GFS AND GEM TRACKS. THIS
SHOULD HELP KEEP WED NITE DRY BEFORE THE NEXT SYSTEM APPROACHES.
LOWS ABOVE NORMAL.
AS THE UPPER LOW MOVES TOWARD THE AREA THU...A VERY COLD AIR MASS
MOVES INTO THE AREA. THE GEFS HAS H85 TEMPS 1 TO 1.5 STANDARD
DEVIATIONS BELOW NORMAL. ALONG WITH THE COLD IS LOW LEVEL MOISTURE
MOVING IN FROM THE NW. THIS SETS UP THE POTENTIAL FOR A NW FLOW
PRECIP EVENT FROM THU THRU FRI NITE. EVEN THOUGH THE H85 TEMPS
REMAIN BELOW FREEZING...THE SFC TEMPS RISE ABOVE FREEZING DURING THE
DAY. THEREFORE...HAVE PRECIP STARTING AS RAIN THU AFT...THEN
CHANGING TO RAIN THU NITE. THIS TREND CONTINUES FRIDAY AS SNOW
CHANGES TO RAIN DURING THE DAY...THEN BACK TO SNOW OVERNIGHT. SOME
RAIN COULD DEVELOP OUTSIDE OF THE MTNS THU AFTERNOON...BUT PRECIP
SHOULD REMAIN LIMITED TO THE NORMAL MTN LOCATIONS AFTER. KEPT POPS
AT SLIGHT CHC FOR NOW GIVEN THE MDL TENDENCY TO OVER FORECAST THE
PRECIP AND AMOUNT OF COLD AIR FOR THESE EVENTS IN THE MEDIUM RANGE.
IT IS WAY TOO EARLY TO KNOW IF ADVISORY LEVEL OR HIGHER SNOW AMOUNTS
WILL DEVELOP. HIGHS THU BELOW NORMAL WEST AND NEAR NORMAL EAST.
TEMPS THEN BELOW NORMAL THU NITE THRU FRI NITE.
HAVE FCST PRECIP ENDING FRI NITE...BUT IT COULD LINGER SATURDAY. DRY
FCST SAT NITE. TEMPS REMAIN BELOW NORMAL.
&&
.AVIATION /09Z SUNDAY THROUGH THURSDAY/...
AT KCLT AND ELSEWHERE...UPSTREAM OBS AND SATELLITE IMAGERY INDICATE
THAT SCT TO BKN CLOUDS IN THE 10-15 KFT LAYER ARE JUST NOW MAKING
THEIR WAY ACROSS NORTH AND CENTRAL GA. AS SUCH...EXPECT THAT THROUGH
LATE MORNING ALL TAF SITES WILL NOTHING MORE THAN SCT MID LEVEL
CLOUDS WITH BKN TO OVC CIRRUS LAYER AND GENERALLY LIGHT NE FLOW.
BIGGEST CHALLENGE OF THE PRESENT TAF PERIOD REVOLVES AROUND TIMING
OF THE LOWERING OF THE CLOUD DECK AND ONSET OF PRECIP. AN
INVESTIGATION OF SOUNDINGS ACROSS THE AREA INDICATE THAT THERE IS
SUBSTANTIAL DRY AIR FROM THE SURFACE UP TO AROUND 600 MB...WHICH
MEANS IT WILL TAKE A WHILE FOR EVEN A VFR LEVEL CIG TO DEVELOP. THIS
BRINGS THINGS DOWN FIRST AT KAND WITH MVFR LEVEL CIGS AND -RA
DEVELOPING AROUND NOON. I DO BRING IN MVFR DECK AT ALL SITES IN THE
AFTERNOON AS DEEP LAYER MOISTURE INCREASES THROUGHOUT THE DAY. IN
FACT MODEL SOLUTIONS SHOW THAT RAPID DETERIORATION OF CONDITIONS
WON/T OCCUR UNTIL AFTER 00Z. MODELS ARE IN PRETTY GOOD AGREEMENT
THAT THE GREATEST COVERAGE OF PRECIP WILL OCCUR LATE IN THE TAF
PERIOD AS A SECONDARY SURGE OF ISENTROPIC LIFT SPREADS ACROSS THE
REGION. WILL HINT AT THE DEVELOPMENT OF IFR CIGS WITH A MENTION OF
FEW009 FROM KAND TO KCLT IN THE 01-02Z TIME FRAME.
OUTLOOK...CEILING AND VISIBILITY SHOULD COME CRASHING DOWN TO IFR
AND LIFR SUNDAY NIGHT AS MAIN PRECIP AREA MOVES THROUGH. ONCE
ESTABLISHED...THE COLD AIR DAMMING WEDGE WILL PERSIST THROUGH MONDAY
NIGHT WITH WIDESPREAD IFR CONDITIONS. THE MODEL GUIDANCE SHOWS
IMPROVEMENT TUESDAY BUT MOST LIKELY AT BEST MVFR SHOULD BE EXPECTED
UNTIL WEDNESDAY.
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...RWH
NEAR TERM...BSH
SHORT TERM...JAT
LONG TERM...RWH
AVIATION...BSH/PM
000
FXUS62 KCAE 220725
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
225 AM EST SUN NOV 22 2009
.SYNOPSIS...
A LOW PRESSURE SYSTEM ALONG THE GULF COAST REGION WILL MOVE SLOWLY
NORTHEAST ACROSS THE FLORIDA PANHANDLE TODAY THEN REFORM ALONG THE
CAROLINA COAST TONIGHT. HIGH PRESSURE WILL WEDGE INTO THE
CAROLINAS FROM THE NORTH. THIS PATTERN WILL BRING CLOUDS AND RAIN
TO THE AREA THROUGH MONDAY.
&&
.NEAR TERM /THROUGH TODAY/...
SURFACE LOW AT 07Z OVER LOUISIANA MOVING SLOWLY NORTHEAST TODAY.
RADAR AT 07Z SHOWING RAIN MOVING INTO WESTERN GEORGIA. HIGH
PRESSURE OVER THE MID ATLANTIC/NORTHEASTERN STATES EXTENDING INTO
THE CAROLINAS. COLD AIR DAMMING WEDGE DEVELOPING. MODELS IN
AGREEMENT WITH STRONG ISENTROPIC LIFT/MOISTURE FLUX OVER THE AREA
THIS AFTERNOON. TEMPERATURES COOLER THAN PREVIOUS FORECAST AT 06Z
WITH MID TO HIGH LEVEL CLOUDS ADVECTING INTO THE AREA. CUT MAXIMUM
TEMPERATURES SLIGHTLY DUE TO COOLER START TO THE DAY/WEDGE
SCHEME...OTHERWISE VERY LITTLE CHANGES MADE. CATEGORICAL POPS
DEVELOPING FROM CSRA MID MORNING TO NORTHERN MIDLANDS THIS AFTERNOON.
&&
.SHORT TERM /TONIGHT THROUGH TUESDAY/...
WEAKENING SHORT WAVE WILL CROSS GEORGIA INTO THE CAROLINAS
TONIGHT. LOW PRESSURE DEVELOPING ON AN INVERTED TROUGH OFF THE SC
COAST. KEPT CATEGORICAL POPS THROUGH EARLY TONIGHT THEN
DIMINISHING AS ISENTROPIC LIFT SHIFTS NORTH AND WEST. RAINFALL
AMOUNTS RANGING FROM ONE HALF INCH TO AROUND ONE INCH. THE SURFACE
LOW WILL MOVE AWAY FROM THE COAST MONDAY WITH RAIN CHANCES
DECREASING. KEPT CHANCE OF DRIZZLE IN FOR MONDAY NIGHT INTO
TUESDAY WITH WEDGE POSSIBLY HOLDING AND HIGH LOW-LEVEL MOISTURE
SUGGESTED BY MODEL T-SECTIONS. COOLER THAN MOS GUIDANCE MAXIMUM
TEMPERATURE FORECAST DUE TO WEDGE.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
MEDIUM RANGE MODELS DEPICT A SERIES OF MID/UPPER LEVEL LOWS MOVING
ACROSS THE UPPER MIDWEST TO THE EASTERN GREAT LAKES AND
SOUTHEASTERN CANADA TUESDAY NIGHT INTO SATURDAY. ALL IN ALL,
SLIGHT UPPER RIDGING OVER THE SOUTHEAST PART OF THE COUNTRY
TUESDAY IS REPLACED BY A LARGE UPPER TROUGH OVER THE EASTERN
UNITED STATES WEDNESDAY THROUGH FRIDAY. UPPER TROUGH FINALLY MOVES
OFF THE EAST COAST SATURDAY. SURFACE HIGH PRESSURE CENTERED OVER
SOUTHEASTERN CANADA TUESDAY NIGHT RIDGING INTO THE AREA FROM THE
NORTH. SURFACE LOW PRESSURE CROSSING THE GREAT LAKES REGION ON
THANKSGIVING DAY WILL DRAG A COLD FRONT ACROSS THE AREA. MOISTURE
APPEARS LIMITED SINCE THE BEST ISENTROPIC LIFT REMAINS SOUTH AND
EAST OF THE FORECAST AREA. ANY CHANCE FOR RAIN (WHICH IS SLIGHT)
LOOKS LIKE WEDNESDAY INTO THURSDAY MORNING. COOL HIGH PRESSURE
BUILDS IN FOR FRIDAY AND SATURDAY. WILL KEEP THE EXTENDED FORECAST
DRY. SEASONABLY MILD MAX TEMPERATURES WEDNESDAY AND THURSDAY COOL
A FEW DEGREES BELOW NORMAL FOR FRIDAY AND SATURDAY. NIGHTTIME LOWS
IN THE 40S MID-WEEK COOLING TO THE MID AND UPPER 30S BY LATE NEXT
WEEK.
&&
.AVIATION /07Z SUNDAY THROUGH THURSDAY/...
HIGH PRESSURE OVER THE MID-ATLANTIC STATES WILL MOVE OFFSHORE AS A
LOW PRESSURE SYSTEM OVER THE GULF OF MEXICO MOVES NORTHEAST. THIS
LOW WILL TRACK OVER THE SE STATES ON SUNDAY BRINGING RAIN WITH
MVFR/IFR CONDITIONS TO THE AREA. THE TAF PERIOD WILL START OUT VFR
WITH MVFR CIGS DEVELOPING BY AROUND 12Z-14Z WITH SOME SPRINKLES
POSSIBLE BY THEN. CONDITIONS BECOME IFR BY LATE SUNDAY AFTERNOON AS
PRECIPITATION SPREADS ACROSS THE REGION.
EXTENDED AVIATION OUTLOOK...WIDESPREAD MVFR OR IFR CONDITIONS WILL
CONTINUE INTO MONDAY AS THE LOW PRESSURE SYSTEM MOVES THROUGH THE
AREA. CONDITIONS SHOULD IMPROVE TO VFR BY LATE TUESDAY AS THE LOW
MOVES OUT OF THE AREA.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
SYNOPSIS...10
NEAR TERM...10
SHORT TERM...10
LONG TERM...10
AVIATION...
000
FXUS62 KCAE 220615
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
115 AM EST SUN NOV 22 2009
.SYNOPSIS...
A LOW PRESSURE SYSTEM IN THE NORTHWEST GULF OF MEXICO WILL MOVE
SLOWLY NORTHEAST TO THE FLORIDA PANHANDLE TONIGHT...THEN REFORM
ALONG THE CAROLINA COAST SUNDAY NIGHT. HIGH PRESSURE WILL WEDGE
INTO THE CAROLINAS FROM THE NORTH. THIS PATTERN WILL BRING CLOUDS
AND RAIN TO THE AREA THROUGH MONDAY.
&&
.NEAR TERM /TONIGHT/...
CLOUDS CONTINUE TO INCREASE ACROSS THE REGION THIS EVENING AHEAD
OF AN AREA OF LOW PRESSURE NOW BEING SHOWN ON SATELLITE OVER
SOUTHEASTERN LA. LOW LEVEL WEDGE FLOW FROM THE NORTH CONTINUES
OVER THE REGION. LEADING EDGE OF PRECIP BACK ACROSS SOUTHWESTERN
GA HAVING HARD TIME ADVANCING INTO DRIER AIR TONIGHT. UPDATED
FORECAST TO HAVE DRY OVERNIGHT ALL AREAS...AND TO ADJUST OVERNIGHT
LOWS DOWNWARD SLIGHTLY.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
MODELS FINALLY IN AGREEMENT WITH STRONG ISENTROPIC LIFT OVER THE
AREA SUNDAY AFTERNOON INTO SUNDAY NIGHT. WEAKENING SHORT WAVE
MOVING OUT OF TEXAS TONIGHT WILL CROSS GA INTO THE CAROLINAS
SUNDAY NIGHT. LOW PRESSURE DEVELOPING ON AN INVERTED TROUGH OFF
THE SC COAST. KEPT CATEGORICAL POPS FOR SUNDAY INTO SUNDAY NIGHT.
RAINFALL AMOUNTS RANGING FROM ONE HALF INCH TO AROUND ONE INCH.
THE SURFACE LOW WILL MOVE AWAY FROM THE COAST MONDAY WITH RAIN
CHANCES DECREASING. KEPT CHANCE OF DRIZZLE IN FOR MONDAY NIGHT
INTO TUESDAY.
SINCE WEDGE PATTERN EXPECTED SUNDAY THROUGH TUESDAY...SHOULD SEE
PLENTY OF CLOUDS. KEPT DAYTIME TEMPERATURES BELOW GUIDANCE. HIGHS
IN THE LOW TO MID 50S (WHICH MAY BE ON THE HIGH SIDE). LITTLE DIURNAL
CHANGE IN TEMPERATURES EXPECTED. LOWS IN THE MID TO UPPER 40S.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
MEDIUM RANGE MODELS DEPICT A SERIES OF MID/UPPER LEVEL LOWS MOVING
ACROSS THE UPPER MIDWEST TO THE EASTERN GREAT LAKES AND
SOUTHEASTERN CANADA TUESDAY NIGHT INTO SATURDAY. ALL IN ALL,
SLIGHT UPPER RIDGING OVER THE SOUTHEAST PART OF THE COUNTRY
TUESDAY IS REPLACED BY A LARGE UPPER TROUGH OVER THE EASTERN
UNITED STATES WEDNESDAY THROUGH FRIDAY. UPPER TROUGH FINALLY MOVES
OFF THE EAST COAST SATURDAY. SURFACE HIGH PRESSURE CENTERED OVER
SOUTHEASTERN CANADA TUESDAY NIGHT RIDGING INTO THE AREA FROM THE
NORTH. SURFACE LOW PRESSURE CROSSING THE GREAT LAKES REGION ON
THANKSGIVING DAY WILL DRAG A COLD FRONT ACROSS THE AREA. MOISTURE
APPEARS LIMITED SINCE THE BEST ISENTROPIC LIFT REMAINS SOUTH AND
EAST OF THE FORECAST AREA. ANY CHANCE FOR RAIN (WHICH IS SLIGHT)
LOOKS LIKE WEDNESDAY INTO THURSDAY MORNING. COOL HIGH PRESSURE
BUILDS IN FOR FRIDAY AND SATURDAY. WILL KEEP THE EXTENDED FORECAST
DRY. SEASONABLY MILD MAX TEMPERATURES WEDNESDAY AND THURSDAY COOL
A FEW DEGREES BELOW NORMAL FOR FRIDAY AND SATURDAY. NIGHTTIME LOWS
IN THE 40S MID-WEEK COOLING TO THE MID AND UPPER 30S BY LATE NEXT
WEEK.
&&
.AVIATION /06Z SUNDAY THROUGH FRIDAY/...
HIGH PRESSURE OVER THE MID-ATLANTIC STATES WILL MOVE OFFSHORE AS A
LOW PRESSURE SYSTEM OVER THE GULF OF MEXICO MOVES NORTHEAST. THIS
LOW WILL TRACK OVER THE SE STATES ON SUNDAY BRINGING RAIN WITH
MVFR/IFR CONDITIONS TO THE AREA. THE TAF PERIOD WILL START OUT VFR
WITH MVFR CIGS DEVELOPING BY AROUND 12Z-14Z WITH SOME SPRINKLES
POSSIBLE BY THEN. CONDITIONS BECOME IFR BY LATE SUNDAY AFTERNOON AS
PRECIPITATION SPREADS ACROSS THE REGION.
EXTENDED AVIATION OUTLOOK...WIDESPREAD MVFR OR IFR CONDITIONS WILL
CONTINUE INTO MONDAY AS THE LOW PRESSURE SYSTEM MOVES THROUGH THE
AREA. CONDITIONS SHOULD IMPROVE TO VFR BY LATE TUESDAY AS THE LOW
MOVES OUT OF THE AREA.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
000
FXUS62 KGSP 220550
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1250 AM EST SUN NOV 22 2009
.SYNOPSIS...
HIGH PRESSURE OVER THE REGION WILL SHIFT NORTH OVER THE WEEKEND.
THIS WILL ALLOW A LOW PRESSURE SYSTEM TO MOVE EAST ALONG THE GULF
COAST THEN NORTH ALONG THE CAROLINA COAST SUNDAY THROUGH MONDAY.
THE LOW IS EXPECTED TO REACH THE NEW ENGLAND COAST BY TUESDAY AS
WEAK HIGH PRESSURE REMAINS OVER THE SOUTHEAST STATES. ANOTHER COLD
FRONT OR COASTAL LOW COULD MOVE INTO THE AREA BY THE MIDDLE OF NEXT
WEEK.
&&
.NEAR TERM /THROUGH TODAY/...
TEMPS CONTINUE TO FALL FASTER THAN FORECAST...APART FROM NE GEORGIA
WHERE THE LEADING EDGE OF THE MID LEVEL CLOUDINESS IS ADVANCING AS
OF 03Z. WILL ADJUST LOW TEMPS DOWN A FEW DEGREES MAINLY ACROSS THE
NC FOOTHILLS AND PIEDMONT...WHICH WILL NOT CLOUD UP QUICK ENOUGH TO
KEEP TEMPS FROM REACHING THE OLD FORECAST. OTHERWISE...THE REST OF
THE FORECAST WILL BE LEFT ALONE.
CONFLUENT FLOW OFF THE NEW ENGLAND COAST WILL GRADUALLY STRENGTHEN
SFC HIGH PRESSURE OVER THE MID ATLANTIC STATES THROUGH SUNDAY. THE
MORNING UPPER AIR SHOWED VERY DRY AIR DOWN ALONG THE GULF COAST. FOR
EXAMPLE...THE TALLAHASSEE RAOB HAD A 40 DEGREE DEWPOINT DEPRESSION
AT 850 MB. WITH THIS MUCH DRY AIR TO THE SOUTH...AND WITH A
DEVELOPING CLASSICAL COLD AIR DAMMING EVENT...IT/S NOT SURPRISING
THAT THE MODELS HAVE BEEN DELAYING THE ONSET OF PCPN OVER THE PAST
SEVERAL RUNS. AT LEAST THE GFS HAS TONED DOWN THE POT VORT MAXES AND
HEAVY PCPN THAT IT HAD BEEN DRIVING ACROSS THE HEART OF THE WEDGE
RIDGE. THIS SEEMS MORE REALISTIC AS QPF SHOULD BE FAIRLY LIGHT
WITH THE LLVL DRY AIR AND THE WEAKENING SRN STREAM SYSTEM. THE BEST
CHANCES FOR HEAVY RAIN WILL BE ALONG THE COASTAL FRONT...WELL TO OUR
SOUTH.
OVERALL...THE SREF SEEMS TO HAVE DONE THE BEST JOB OF HANDLING THE
EVOLUTION OF THE GULF COAST LOW AND PCPN DISTRIBUTION SO FAR. I/VE
FOLLOWED IT FAIRLY CLOSELY FOR THE TIMING OF PCPN. THIS MEANS A DRY
FORECAST TONIGHT. PCPN SHOULD OVERSPREAD THE REGION FROM THE
SOUTHWEST ON SUNDAY...THOUGH I DON/T SEE ANYTHING FALLING NORTH OF
GREENVILLE UNTIL THE AFTERNOON HOURS. I RAISED MAX TEMPS A COUPLE
CATEGORIES OVER THE NE ZONES WHERE THINNER CLOUD COVER EARLY IN THE
DAY WILL RESULT IN A LITTLE MORE WARMING THAN ORIGINALLY EXPECTED. I
FOLLOWED A MET/MAV BLEND AND WE MATCH UP WELL WITH THE NEIGHBORS.
&&
.SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/...
AS OF 130 PM SATURDAY...NOT THAT THERE IS A GREAT DEAL OF CONFIDENCE
WITH REGARDS TO THE SPECIFICS OF THE SUNDAY NIGHT FCST...BUT LIKELY
SOME DEGREE OF DEEP RH AND ESE FLOW ABOVE LINGERING WEDGE WILL REMAIN
ALL NIGHT. SENSIBLE WX IS STILL EXPECTED TO BE DAMP WITH RAINY AND
DRIZZLY PERIODS...ALTHOUGH PCPN TOTALS WILL BE MODERATE AT WORST.
CONFIDENCE INCREASING THAT DAMMING REGIME WILL REMAIN THRU
MONDAY...ALTHOUGH FORCING FOR ADDITIONAL PCPN WILL WANE...EVENTUALLY
JUST BEING FORCED BY SOME DEGREE OF WAA/EASTERLY FLOW JUST ABV SFC.
EVEN THE MILDER 12 UTC MET NUMBERS...WHICH WILL PROBABLY BE TOO WARM
ANYWAY...SUPPORT NOTABLE LOWERING OF GOING MAX TEMPS. GIVEN THE
WEAKENING OF THE LLVL FLOW MONDAY NIGHT AND RESIDUAL WEAK SFC
RIDGING...THERE SEEMS TO BE LITTLE HOPE OF SCOURING...SO WILL PLAN
ON LEAVING OVC CONDS WITH SPOTTY AREAS OF LIGHT RAIN/DRIZZLE...
ESPECIALLY ALONG AND EAST OF THE ESCARPMENT WHERE WEAK LLVL
EASTERLY FLOW WILL CONTINUE TO LIFT SHALLOW MOISTURE.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
AS OF 145 PM SATURDAY...NOT MUCH AGREEMENT IS SEEN IN THE OP MODELS
WITH RESPECT TO AMOUNT OF DEEPENING OF THE MID WEEK CUT OFF LOW AND
THE LEVEL OF MOISTURE AVAILABLE FOR THE OCCLUDED FRONT TO WORK WITH
ONCE IT REACHES THE CWFA WED MORNING. EVEN LESS AGREEMENT IS SEEN
BETWEEN THE GFS AND THE ECMWF ON THU/FRI WITH THE POLAR VORTEX
REINFORCING THE GLAKES LOW AND THE EVENTUAL TRACK AND SPEED OF THE
LARGE SCALE PATTERN. THE GFS H5 ENS MEMBERS SHOW THE HIGHEST SPREAD
EARLY FRI MORNING WITH ABOUT 8 DM OF UNCERTAINTY ASSOCIATED WITH
THE HEIGHT FIELD...LENDING LOW CONFIDENCE TOWARD THE SETUP FOR A
POSSIBLE MINIMAL NW FLOW EVENT.
NOT MANY CHANGES HAVE BEN MADE TO THE GOING FORECAST WITH LITTLE
CONFIDENCE HAD BOTH IN THE OP MODELS AND HPC GUIDANCE. SOME DECENT
AGREEMENT IS SEEN TUE WITH THE SLOWER BREAKDOWN OF THE SFC WEDGE.
MODEL SOUNDINGS INDICATE RATHER THICK STRATUS HANGING ON THROUGHOUT
THE DAY AND VERY LOW WINDS IN THE BL. SO...MAX TEMP GUIDANCE HAS
BEEN CUT BACK A CAT OR SO OUTSIDE THE MTNS TO ACCOUNT FOR THIS
POSSIBLE SCENARIO. POPS STILL SEEM SUSPECT WITH LITTLE IN THE WAY OF
ORGANIZED FLOW INTERACTING OVER THE WEDGE...SO THE LINGERING SLIGHT
CHANCES WERE CHANGED LITTLE.
THE GFS IS MORE AGGRESSIVE IN BRINGING A MOIST OCCLUDED FRONT TO THE
MTNS BY 12Z WED THAN THE ECMWF. THE EC DOES EVENTUALLY BRING THE
FRONT TO THE AREA LATE IN THE DAY...BUT BOTH MODELS CUT OFF THE GOM
MOISTURE FLUX WITH LLVL RIDGING FROM THE WEST. WITH THE MAIN LARGE
SCALE FORCING SHIFTED NORTH...WILL COUNT ON VERY LITTLE IMPACT AS
FAR A PRECIP COVERAGE GOES. FOR NOW...SLIGHT CHANCES WILL
REMAIN...BUT THIS COULD BE INCREASED ONCE BETTER DATA IS GLEANED ON
THIS SYSTEM.
THE NEXT SYSTEM TO THINK ABOUT WILL BE THU/FRI...AS THE GFS INSISTS
ON A MOIST NW FLOW EVENT...YET THE EC REMAINS DRY AND LOW KEY ON THE
KINEMATIC SETUP. THE GFS AS MENTIONED EARLIER IS BRINGING IN A MUCH
STRONGER REINFORCING POLAR VORTEX INTO THE GLAKES LOW...ABOUT TWICE
AS STRONG PVU/WISE THAN THE ECMWF. THIS SEEMS A LITTLE TOO STRONG
FOR THIS TIME OF YEAR...AND FOR NOW WILL SIDE WITH THE MORE
CONSERVATIVE ECMWF ON THIS ONE. THUS...MINIMAL POPS AND AN ALL RAIN
P/TYPE ARE ADVERTISED FOR THAT PERIOD.
OTHER THAN THE LOWER THAN NORMAL POPS EXPECTED TUE....MAX TEMPS
SHOULD REBOUND RATHER NICELY WED THROUGH FRI. INCREASED INSOLATION
AND A WAA FLOW WILL ENABLE MAXES AT OR PERHAPS A COUPLE DEGREES
ABOVE NORMAL. THE NC MTNS WILL BE TRICKERY FRI...AS IT/S PROBABLE
THAT CAA ASSOCIATED WITH THE PASSING VORTEX TO THE NORTH LOWERS
TEMPS THROUGHOUT THE DAY. YET FOR NOW...WILL ONLY GO A COUPLE
DEGREES BELOW NORMAL WITH SO MUCH UNCERTAINTY AND POOR CONTINUITY
DISPLAYED BY THE GUIDANCE.
&&
.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
AT KCLT AND ELSEWHERE...UPSTREAM OBS AND SATELLITE IMAGERY INDICATE
THAT SCT TO BKN CLOUDS IN THE 10-15 KFT LAYER ARE JUST NOW MAKING
THEIR WAY ACROSS NORTH AND CENTRAL GA. AS SUCH...EXPECT THAT THROUGH
LATE MORNING ALL TAF SITES WILL NOTHING MORE THAN SCT MID LEVEL
CLOUDS WITH BKN TO OVC CIRRUS LAYER AND GENERALLY LIGHT NE FLOW.
BIGGEST CHALLENGE OF THE PRESENT TAF PERIOD REVOLVES AROUND TIMING
OF THE LOWERING OF THE CLOUD DECK AND ONSET OF PRECIP. AN
INVESTIGATION OF SOUNDINGS ACROSS THE AREA INDICATE THAT THERE IS
SUBSTANTIAL DRY AIR FROM THE SURFACE UP TO AROUND 600 MB...WHICH
MEANS IT WILL TAKE A WHILE FOR EVEN A VFR LEVEL CIG TO DEVELOP. THIS
BRINGS THINGS DOWN FIRST AT KAND WITH MVFR LEVEL CIGS AND -RA
DEVELOPING AROUND NOON. I DO BRING IN MVFR DECK AT ALL SITES IN THE
AFTERNOON AS DEEP LAYER MOISTURE INCREASES THROUGHOUT THE DAY. IN
FACT MODEL SOLUTIONS SHOW THAT RAPID DETERIORATION OF CONDITIONS
WON/T OCCUR UNTIL AFTER 00Z. MODELS ARE IN PRETTY GOOD AGREEMENT
THAT THE GREATEST COVERAGE OF PRECIP WILL OCCUR LATE IN THE TAF
PERIOD AS A SECONDARY SURGE OF ISENTROPIC LIFT SPREADS ACROSS THE
REGION. WILL HINT AT THE DEVELOPMENT OF IFR CIGS WITH A MENTION OF
FEW009 FROM KAND TO KCLT IN THE 01-02Z TIME FRAME.
OUTLOOK...CEILING AND VISIBILITY SHOULD COME CRASHING DOWN TO IFR
AND LIFR SUNDAY NIGHT AS MAIN PRECIP AREA MOVES THROUGH. ONCE
ESTABLISHED...THE COLD AIR DAMMING WEDGE WILL PERSIST THROUGH MONDAY
NIGHT WITH WIDESPREAD IFR CONDITIONS. THE MODEL GUIDANCE SHOWS
IMPROVEMENT TUESDAY BUT MOST LIKELY AT BEST MVFR SHOULD BE EXPECTED
UNTIL WEDNESDAY.
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...PAT
NEAR TERM...MCAVOY/PM
SHORT TERM...CSH
LONG TERM...SBK
AVIATION...BSH/PM
000
FXUS62 KCHS 220546
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
1246 AM EST SUN NOV 22 2009
.SYNOPSIS...
HIGH PRESSURE WILL REMAIN NORTH OF THE REGION THROUGH TONIGHT. AN
AREA OF LOW PRESSURE WILL TRACK ALONG THE GULF COAST STATES AND
INTO THE ATLANTIC OFF THE SOUTHEAST GEORGIA COAST SUNDAY NIGHT AND
MONDAY...THEN MOVE NORTHEAST ALONG THE EASTERN SEABOARD. A HIGH
PRESSURE WEDGE WILL THEN DOMINATE INTO MID WEEK. LOW PRESSURE WILL
PASS OFF THE SOUTHEAST U.S. COAST ON THURSDAY...THEN WILL BE
FOLLOWED BY COLDER HIGH PRESSURE FROM THE WEST INTO THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
A 1008 MB LOW IS FOUND ALONG THE SOUTHERN COAST OF LA/MS...MOVING
SLOWLY EASTWARD...WHILE 1025 MB HIGH IS CENTERED OVER LAKE ERIE
AND IS WEDGING SOUTH INTO NORTHERN FLORIDA. THE CENTER OF THE HIGH
WILL SHIFT EASTWARD THROUGH THE NIGHT...WITH THE WEDGE BECOMING
FURTHER ESTABLISHED ACROSS THE AREA AS RAINS START BREAKING OUT
ACROSS SOUTHERN GA IN ASSOCIATION WITH A DEVELOPING WARM FRONT TO
THE SOUTH AND SHORT WAVES MOVING NE FROM THE GULF. AS THE WEDGE
STRENGTHENS AND ISENTROPIC LIFT INCREASES WE LOOK FOR AN INCREASE
IN VERTICAL MOISTURE THROUGH THE NIGHT...MAINLY FAR SOUTH...AS
PWATS RISE TO 1-1.25 INCHES SOUTH OF I-16 IN SE GA LATE. GIVEN
THAT THE LEADING EDGE OF THE PRECIP IS ALREADY A LITTLE FURTHER NE
THAN MODEL GUIDANCE DEPICTS...I FEEL COMPELLED TO ADD AT LEAST
SMALL POPS TO FAR SW ZONES LATE TONIGHT...BEGINNING AROUND 4 AM.
CLOUD COVER HAS DISPERSED A BIT SINCE THIS AFTERNOON IN SOME
AREAS...AND HAS ALLOWED FOR TEMPS TO FALL CLOSE TO OUR EARLIER MIN
TEMP FORECAST. BUT WITH CONSIDERABLE MID AND HIGH LEVEL CLOUDINESS
JUST UPSTREAM...TEMP FALL WILL SLOW OR EVEN REVERSE OVERNIGHT. WE
WILL HOWEVER TWEAK TEMPS DOWN INTO THE UPPER 40S AND LOWER 50S
MOST INLAND LOCATIONS...BUT HOLDING IN THE MID AND UPPER 50S
CLOSER TO THE COAST WITH MODERATE NE WINDS DEVELOPING.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM MONDAY/...
A COASTAL TROUGH WILL FURTHER STRENGTHEN OFF THE NC/SC COAST
SUNDAY MORNING...INCREASING ISENTROPIC ASCENT FROM THE E.
MEANWHILE THE RESIDUAL GULF LOW WILL MOVE INTO THE FL
PANHANDLE...ADVECTING QUITE A BIT OF LOW-LEVEL MOISTURE INTO
SOUTHEAST GA AND CENTRAL SC. RAIN SHOULD OVERSPREAD THE ENTIRE
AREA BY LATE MORNING. WE LEFT ISOLATED THUNDERSTORMS ACROSS FAR
SOUTHEASTERN PORTIONS IN THE AFTERNOON DUE TO A SLUG OF 6C
700-500 MB LAPSE RATES PROGGED TO TREK THROUGH. COLD ADVECTION AND
EVAPORATIONAL COOLING WILL KEEP TEMPERATURES FROM INCREASING VERY
MUCH AFTER DAYBREAK. HIGHS WILL PROBABLY NOT GET ABOVE 60F.
&&
.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
GUIDANCE IS IN GOOD AGREEMENT EJECTING WEAKENING SURFACE LOW
PRESSURE OFF THE GEORGIA COAST SUNDAY NIGHT...THEN TRACKING IT
NORTHEAST ALONG THE CAROLINA COAST INTO MONDAY. AS THIS
OCCURS...OVERRUNNING PRECIPITATION WILL ALLOW A HIGH PRESSURE WEDGE
TO BECOME SOLIDLY ENTRENCHED TO THE LEE OF THE APPALACHIANS AS THE
PARENT HIGH STRENGTHENS OVER NEW ENGLAND. THERE IS SOME UNCERTAINTY
AS TO HOW QUICKLY THE WIDESPREAD RAIN WILL TAPER OFF FROM THE
SOUTHWEST SUNDAY NIGHT...AND SOME CONSIDERATION NEEDS TO BE GIVEN TO
THE NAM WHICH SHOWS A DRY SLOT DEVELOPING OVER THE AREA. AS A
RESULT...THE FORECAST WILL SHOW CATEGORICAL RAIN CHANCES TOWARD THE
SANTEE RIVER DECREASING TO ONLY A CHANCE OF RAIN TOWARD THE ALTAMAHA
RIVER SUNDAY EVENING. RAIN CHANCES LATE SUNDAY NIGHT WILL CONTINUE
TO DIMINISH AS THE DEEPEST MOISTURE SHIFTS NORTH AND EAST OF THE
AREA. AS FOR MONDAY...DEEP MOISTURE WILL BE LACKING BUT PLENTY OF
LOW LEVEL MOISTURE WITHIN THE WEDGE COULD SUPPORT A SLIGHT CHANCE OF
LIGHT RAIN AND/OR DRIZZLE ACROSS THE AREA. TEMPERATURES WILL ALSO BE
SEVERELY IMPACTED BY THE WEDGE...AND GUIDANCE APPEARS MUCH TOO WARM
GIVEN THE EXPECTED SCENARIO...THEREFORE WILL FORECAST HIGHS IN THE
MID 50S WELL INLAND TO AROUND 60 TOWARD THE COAST ON MONDAY.
THE HIGH PRESSURE WEDGE SHOULD PERSIST INTO TUESDAY...BEFORE
GRADUALLY ERODING AS THE PARENT HIGH SHIFTS OFF THE NEW ENGLAND
COAST. ABUNDANT LOW LEVEL MOISTURE WILL KEEP CONSIDERABLE CLOUDINESS
IN PLACE...ALONG WITH THE POTENTIAL FOR AT LEAST PATCHY DRIZZLE.
HIGH TEMPERATURES TUESDAY MAY MODERATE SOME...BUT SHOULD REMAIN
BELOW NORMAL AND WELL BELOW WHAT GUIDANCE SUGGESTS.
WEDNESDAY WILL BE A TRANSITION DAY...WITH DRY CONDITIONS AND NEAR
NORMAL TEMPERATURES EXPECTED. LOW PRESSURE IS EXPECTED TO TRACK
OFFSHORE ALONG THE SOUTHEAST U.S. COAST WEDNESDAY NIGHT INTO
THURSDAY...BUT THERE IS SOME MODEL DISAGREEMENT AS TO HOW FAR
OFFSHORE. THEREFORE...WILL SHOW SOME ISOLATED SHOWERS IN THE
FORECAST FOR WEDNESDAY NIGHT. COOL AND DRY HIGH PRESSURE WILL THEN
BUILD FROM THE WEST LATE IN THE WORK WEEK THROUGH THE FIRST PART OF
THE WEEKEND.
&&
.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
KCHS...HIGH PRES WEDGE HOLDS IN PLACE TONIGHT WITH ANTICYCLONIC
FLOW...AND ONLY LIMITED MOISTURE TO BE FOUND IN PLACE. THUS WE
HAVE MAINTAINED VFR WEATHER THROUGH THE MORNING HOURS. HOWEVER...
SHORT WAVE NOW MOVING INTO THE NE GULF OF MEXICO WILL MOVE
THROUGH AFTER DAYBREAK AND RESULT IN SOME LIGHT RAINS DEVELOPING
AROUND 15Z...AND ALSO FOR A LOWERING OF THE CIGS TO AROUND 5K
FEET. THE COMBINATION OF INCREASING LOW LEVEL CONVERGENCE...
ISENTROPIC LIFT AND SHORT WAVES ALOFT WILL PRODUCE A HEAVIER AND
STEADIER RAIN OVERSPREADING THE AREA DURING THE AFTERNOON...AND
WITH IT OUR CONDITIONS WILL DROP TO MVFR AT 18Z AND TO IFR AT 21Z.
NE WINDS SHOULD BEGIN TO GUST OVER 15 KT LATE IN THE AFTERNOON AND
WE EXPECTED A DECENT POTENTIAL FOR SURFACE FLOW GUSTING INTO THE
15 TO 20 KT RANGE TOWARD THE END OF TAF CYCLE. IFR CIGS AND VSBYS
INTO THE LATTER 6 HOURS OF THE TAF CYCLE WITH RAINFALL ANTICIPATED
AND POSSIBLY SOME GUSTY NE SURFACE WINDS AT TIMES.
KSAV...THE HIGH PRES WEDGE AND ITS RESULTING ANTICYCLONIC FLOW
EARLY TONIGHT WILL GIVE WAY TO A SHORT WAVE AND MORE CYCLONIC
CURVATURE OF THE ISOBARS LATE TONIGHT. THIS ALLOWS FOR A STEADY
MOISTENING OF THE LOWER LEVELS AND EVENTUALLY LIGHT RAINS AND A
LOWERING OF THE CIGS TO OCCUR...FALLING TO MVFR AT 14Z. A MORE
SUBSTANTIAL INCREASE IN OVERALL MOISTURE AND LOW LEVEL CONVERGENCE
AND ISENTROPIC LIFT FORMS FOR THE AFTERNOON...AND IFR WEATHER WILL
PREVAIL FROM 18Z ONWARDS. LATER SHIFTS WILL NEED TO KEEP WATCH FOR
A LITTLE ELEVATED CONVECTION THAT WILL ATTEMPT TO DEVELOP LATE
SUNDAY AS SHOWALTER INDICES DROP TO -1 OR -2 AND MID LEVEL LAPSE
RATES APPROACH 6C/KM. GIVEN THE WEDGE IN PLACE AND ATMOSPHERIC
DYNAMICS TAPPED BY THE MODELS WE INCREASING NE SURFACE WINDS INTO
THE 10-15 KT RANGE THIS AFTERNOON AND THERE COULD BE A FEW GUSTS
TO 20 KT AT TIMES. AFTER DUSK...RAIN IS EXPECTED TO TAPER TO
LIGHTER RAINS AND DRIZZLE WITH IFR/LIFR CIGS AND MVFR/IFR VSBYS.
EXTENDED AVIATION OUTLOOK...IFR CONDITIONS ARE LIKELY SUNDAY NIGHT
THROUGH TUE. VFR CONDITIONS MAY RETURN ON WED.
&&
.MARINE...
THERE WILL CONTINUE TO BE ENOUGH PINCHING OF THE PRESSURE GRADIENT
TONIGHT BETWEEN THE INLAND HIGH PRESSURE WEDGE AND THE DEVELOPING
WARM FRONT TO THE SOUTH...THAT 20 KT WINDS ARE COMMON ACROSS THE
ATLANTIC WATERS TONIGHT. EVEN CHARLESTON HARBOR WILL HAVE A SOLID
15 KT. SEAS WILL BUILD TO 5 OR 6 FEET WITHIN 20 NM OF THE
COAST...AND UP TO 6 OR 7 FEET ACROSS THE OUTER GA WATERS. THE
WATERS WILL BE QUITE AGITATED WITH THE NE OR NORTH WIND
WAVES...AND A 2-4 FOOT SWELL WAVE FROM THE EAST EVERY 8-9 SECONDS.
WE WILL CONTINUE THE SCA/S FOR AMZ350-352-374...AND CAREFULLY KEEP
WATCH ON AMZ330-354 SHOULD THE PINCHING GET STRONGER AND INDUCE
HIGHER WINDS/SEAS.
THE PRESSURE GRADIENT WILL INCREASE FURTHER SUNDAY AS THE WEDGE OF
HIGH PRESSURE STRENGTHENS FROM THE NORTH WHILE AN APPROACHING
UPPER TROUGH STRENGTHENS A TROUGH AT THE SURFACE. 20 OR 25 KT
WINDS WILL BE COMMON...WHILE SEAS WILL BE AT LEAST AS HIGH AS 5 TO
7 FEET. SCA/S MAY BE NEEDED FOR AMZ354 AND AMZ330...OTHERWISE
SOLID SCA WILL OCCUR ELSEWHERE.
CONDITIONS WILL BEGIN TO SLOWLY IMPROVE OVER THE WATERS SUNDAY
NIGHT DUE TO A WEAKENING SURFACE PRESSURE GRADIENT AS LOW PRESSURE
EJECTS OFF THE GEORGIA COAST AND TRACKS JUST OFF THE COAST OF
SOUTH CAROLINA. WINDS AND SEAS SHOULD FALL BELOW SMALL CRAFT
ADVISORY CRITERIA OVER THE FAR SOUTHERN SOUTH CAROLINA NEAR SHORE
WATERS SUNDAY EVENING...THEN OVER THE REMAINING SOUTH CAROLINA
NEAR SHORE WATERS AND OUTER GEORGIA WATERS BY LATE SUNDAY NIGHT. A
NORTHERLY FLOW WILL THEN PERSIST THROUGH MID WEEK...WITH SPEEDS 15
KT OR LESS. AN STRENGTHENING OFFSHORE FLOW IS EXPECTED ON THURSDAY
AS STRONG COLD AIR ADVECTION DEVELOPS OVER THE WATERS.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR AMZ352.
SMALL CRAFT ADVISORY UNTIL 5 AM EST MONDAY FOR AMZ350-374.
&&
$$
000
FXUS62 KCAE 220342
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
1042 PM EST SAT NOV 21 2009
.SYNOPSIS...
A LOW PRESSURE SYSTEM IN THE NORTHWEST GULF OF MEXICO WILL MOVE
SLOWLY NORTHEAST TO THE FLORIDA PANHANDLE TONIGHT...THEN REFORM
ALONG THE CAROLINA COAST SUNDAY NIGHT. HIGH PRESSURE WILL WEDGE
INTO THE CAROLINAS FROM THE NORTH. THIS PATTERN WILL BRING CLOUDS
AND RAIN TO THE AREA THROUGH MONDAY.
&&
.NEAR TERM /TONIGHT/...
CLOUDS CONTINUE TO INCREASE ACROSS THE REGION THIS EVENING AHEAD
OF AN AREA OF LOW PRESSURE NOW BEING SHOWN ON SATELLITE OVER
SOUTHEASTERN LA. LOW LEVEL WEDGE FLOW FROM THE NORTH CONTINUES
OVER THE REGION. LEADING EDGE OF PRECIP BACK ACROSS SOUTHWESTERN
GA HAVING HARD TIME ADVANCING INTO DRIER AIR TONIGHT. UPDATED
FORECAST TO HAVE DRY OVERNIGHT ALL AREAS...AND TO ADJUST OVERNIGHT
LOWS DOWNWARD SLIGHTLY.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
MODELS FINALLY IN AGREEMENT WITH STRONG ISENTROPIC LIFT OVER THE
AREA SUNDAY AFTERNOON INTO SUNDAY NIGHT. WEAKENING SHORT WAVE
MOVING OUT OF TEXAS TONIGHT WILL CROSS GA INTO THE CAROLINAS
SUNDAY NIGHT. LOW PRESSURE DEVELOPING ON AN INVERTED TROUGH OFF
THE SC COAST. KEPT CATEGORICAL POPS FOR SUNDAY INTO SUNDAY NIGHT.
RAINFALL AMOUNTS RANGING FROM ONE HALF INCH TO AROUND ONE INCH.
THE SURFACE LOW WILL MOVE AWAY FROM THE COAST MONDAY WITH RAIN
CHANCES DECREASING. KEPT CHANCE OF DRIZZLE IN FOR MONDAY NIGHT
INTO TUESDAY.
SINCE WEDGE PATTERN EXPECTED SUNDAY THROUGH TUESDAY...SHOULD SEE
PLENTY OF CLOUDS. KEPT DAYTIME TEMPERATURES BELOW GUIDANCE. HIGHS
IN THE LOW TO MID 50S (WHICH MAY BE ON THE HIGH SIDE). LITTLE DIURNAL
CHANGE IN TEMPERATURES EXPECTED. LOWS IN THE MID TO UPPER 40S.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
MEDIUM RANGE MODELS DEPICT A SERIES OF MID/UPPER LEVEL LOWS MOVING
ACROSS THE UPPER MIDWEST TO THE EASTERN GREAT LAKES AND
SOUTHEASTERN CANADA TUESDAY NIGHT INTO SATURDAY. ALL IN ALL,
SLIGHT UPPER RIDGING OVER THE SOUTHEAST PART OF THE COUNTRY
TUESDAY IS REPLACED BY A LARGE UPPER TROUGH OVER THE EASTERN
UNITED STATES WEDNESDAY THROUGH FRIDAY. UPPER TROUGH FINALLY MOVES
OFF THE EAST COAST SATURDAY. SURFACE HIGH PRESSURE CENTERED OVER
SOUTHEASTERN CANADA TUESDAY NIGHT RIDGING INTO THE AREA FROM THE
NORTH. SURFACE LOW PRESSURE CROSSING THE GREAT LAKES REGION ON
THANKSGIVING DAY WILL DRAG A COLD FRONT ACROSS THE AREA. MOISTURE
APPEARS LIMITED SINCE THE BEST ISENTROPIC LIFT REMAINS SOUTH AND
EAST OF THE FORECAST AREA. ANY CHANCE FOR RAIN (WHICH IS SLIGHT)
LOOKS LIKE WEDNESDAY INTO THURSDAY MORNING. COOL HIGH PRESSURE
BUILDS IN FOR FRIDAY AND SATURDAY. WILL KEEP THE EXTENDED FORECAST
DRY. SEASONABLY MILD MAX TEMPERATURES WEDNESDAY AND THURSDAY COOL
A FEW DEGREES BELOW NORMAL FOR FRIDAY AND SATURDAY. NIGHTTIME LOWS
IN THE 40S MID-WEEK COOLING TO THE MID AND UPPER 30S BY LATE NEXT
WEEK.
&&
.AVIATION /04Z SUNDAY THROUGH THURSDAY/...
HIGH PRESSURE OVER THE MID-ATLANTIC STATES WILL MOVE OFFSHORE AS A
LOW PRESSURE SYSTEM OVER THE GULF OF MEXICO MOVES NORTHEAST. THIS
LOW WILL TRACK OVER THE SE STATES ON SUNDAY BRINGING RAIN WITH
MVFR/IFR CONDITIONS TO THE AREA. THE TAF PERIOD WILL START OUT VFR
WITH MVFR CIGS DEVELOPING BY AROUND 12Z-14Z WITH SOME SPRINKLES
POSSIBLE BY THEN. CONDITIONS BECOME IFR BY LATE IN THE TAF PERIOD AS
PRECIPITATION SPREADS ACROSS THE REGION SUNDAY AFTERNOON.
EXTENDED AVIATION OUTLOOK...WIDESPREAD MVFR OR IFR CONDITIONS WILL
CONTINUE LATE SUNDAY INTO EARLY MONDAY AS THE LOW PRESSURE SYSTEM
MOVES THROUGH THE AREA. CONDITIONS WILL IMPROVE TO VFR BY MONDAY
AFTERNOON AS THE LOW MOVES OUT OF THE AREA.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
000
FXUS62 KGSP 220321
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1021 PM EST SAT NOV 21 2009
.SYNOPSIS...
HIGH PRESSURE OVER THE REGION WILL SHIFT NORTH OVER THE WEEKEND.
THIS WILL ALLOW A LOW PRESSURE SYSTEM TO MOVE EAST ALONG THE GULF
COAST THEN NORTH ALONG THE CAROLINA COAST SUNDAY THROUGH MONDAY.
THE LOW IS EXPECTED TO REACH THE NEW ENGLAND COAST BY TUESDAY AS
WEAK HIGH PRESSURE REMAINS OVER THE SOUTHEAST STATES. ANOTHER COLD
FRONT OR COASTAL LOW COULD MOVE INTO THE AREA BY THE MIDDLE OF NEXT
WEEK.
&&
.NEAR TERM /THROUGH SUNDAY/...
TEMPS CONTINUE TO FALL FASTER THAN FORECAST...APART FROM NE GEORGIA
WHERE THE LEADING EDGE OF THE MID LEVEL CLOUDINESS IS ADVANCING AS
OF 03Z. WILL ADJUST LOW TEMPS DOWN A FEW DEGREES MAINLY ACROSS THE
NC FOOTHILLS AND PIEDMONT...WHICH WILL NOT CLOUD UP QUICK ENOUGH TO
KEEP TEMPS FROM REACHING THE OLD FORECAST. OTHERWISE...THE REST OF
THE FORECAST WILL BE LEFT ALONE.
CONFLUENT FLOW OFF THE NEW ENGLAND COAST WILL GRADUALLY STRENGTHEN
SFC HIGH PRESSURE OVER THE MID ATLANTIC STATES THROUGH SUNDAY. THE
MORNING UPPER AIR SHOWED VERY DRY AIR DOWN ALONG THE GULF COAST. FOR
EXAMPLE...THE TALLAHASSEE RAOB HAD A 40 DEGREE DEWPOINT DEPRESSION
AT 850 MB. WITH THIS MUCH DRY AIR TO THE SOUTH...AND WITH A
DEVELOPING CLASSICAL COLD AIR DAMMING EVENT...IT/S NOT SURPRISING
THAT THE MODELS HAVE BEEN DELAYING THE ONSET OF PCPN OVER THE PAST
SEVERAL RUNS. AT LEAST THE GFS HAS TONED DOWN THE POT VORT MAXES AND
HEAVY PCPN THAT IT HAD BEEN DRIVING ACROSS THE HEART OF THE WEDGE
RIDGE. THIS SEEMS MORE REALISTIC AS QPF SHOULD BE FAIRLY LIGHT
WITH THE LLVL DRY AIR AND THE WEAKENING SRN STREAM SYSTEM. THE BEST
CHANCES FOR HEAVY RAIN WILL BE ALONG THE COASTAL FRONT...WELL TO OUR
SOUTH.
OVERALL...THE SREF SEEMS TO HAVE DONE THE BEST JOB OF HANDLING THE
EVOLUTION OF THE GULF COAST LOW AND PCPN DISTRIBUTION SO FAR. I/VE
FOLLOWED IT FAIRLY CLOSELY FOR THE TIMING OF PCPN. THIS MEANS A DRY
FORECAST TONIGHT. PCPN SHOULD OVERSPREAD THE REGION FROM THE
SOUTHWEST ON SUNDAY...THOUGH I DON/T SEE ANYTHING FALLING NORTH OF
GREENVILLE UNTIL THE AFTERNOON HOURS. I RAISED MAX TEMPS A COUPLE
CATEGORIES OVER THE NE ZONES WHERE THINNER CLOUD COVER EARLY IN THE
DAY WILL RESULT IN A LITTLE MORE WARMING THAN ORIGINALLY EXPECTED. I
FOLLOWED A MET/MAV BLEND AND WE MATCH UP WELL WITH THE NEIGHBORS.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/...
AS OF 130 PM SATURDAY...NOT THAT THERE IS A GREAT DEAL OF CONFIDENCE
WITH REGARDS TO THE SPECIFICS OF THE SUNDAY NIGHT FCST...BUT LIKELY
SOME DEGREE OF DEEP RH AND ESE FLOW ABOVE LINGERING WEDGE WILL REMAIN
ALL NIGHT. SENSIBLE WX IS STILL EXPECTED TO BE DAMP WITH RAINY AND
DRIZZLY PERIODS...ALTHOUGH PCPN TOTALS WILL BE MODERATE AT WORST.
CONFIDENCE INCREASING THAT DAMMING REGIME WILL REMAIN THRU
MONDAY...ALTHOUGH FORCING FOR ADDITIONAL PCPN WILL WANE...EVENTUALLY
JUST BEING FORCED BY SOME DEGREE OF WAA/EASTERLY FLOW JUST ABV SFC.
EVEN THE MILDER 12 UTC MET NUMBERS...WHICH WILL PROBABLY BE TOO WARM
ANYWAY...SUPPORT NOTABLE LOWERING OF GOING MAX TEMPS. GIVEN THE
WEAKENING OF THE LLVL FLOW MONDAY NIGHT AND RESIDUAL WEAK SFC
RIDGING...THERE SEEMS TO BE LITTLE HOPE OF SCOURING...SO WILL PLAN
ON LEAVING OVC CONDS WITH SPOTTY AREAS OF LIGHT RAIN/DRIZZLE...
ESPECIALLY ALONG AND EAST OF THE ESCARPMENT WHERE WEAK LLVL
EASTERLY FLOW WILL CONTINUE TO LIFT SHALLOW MOISTURE.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
AS OF 145 PM SATURDAY...NOT MUCH AGREEMENT IS SEEN IN THE OP MODELS
WITH RESPECT TO AMOUNT OF DEEPENING OF THE MID WEEK CUT OFF LOW AND
THE LEVEL OF MOISTURE AVAILABLE FOR THE OCCLUDED FRONT TO WORK WITH
ONCE IT REACHES THE CWFA WED MORNING. EVEN LESS AGREEMENT IS SEEN
BETWEEN THE GFS AND THE ECMWF ON THU/FRI WITH THE POLAR VORTEX
REINFORCING THE GLAKES LOW AND THE EVENTUAL TRACK AND SPEED OF THE
LARGE SCALE PATTERN. THE GFS H5 ENS MEMBERS SHOW THE HIGHEST SPREAD
EARLY FRI MORNING WITH ABOUT 8 DM OF UNCERTAINTY ASSOCIATED WITH
THE HEIGHT FIELD...LENDING LOW CONFIDENCE TOWARD THE SETUP FOR A
POSSIBLE MINIMAL NW FLOW EVENT.
NOT MANY CHANGES HAVE BEN MADE TO THE GOING FORECAST WITH LITTLE
CONFIDENCE HAD BOTH IN THE OP MODELS AND HPC GUIDANCE. SOME DECENT
AGREEMENT IS SEEN TUE WITH THE SLOWER BREAKDOWN OF THE SFC WEDGE.
MODEL SOUNDINGS INDICATE RATHER THICK STRATUS HANGING ON THROUGHOUT
THE DAY AND VERY LOW WINDS IN THE BL. SO...MAX TEMP GUIDANCE HAS
BEEN CUT BACK A CAT OR SO OUTSIDE THE MTNS TO ACCOUNT FOR THIS
POSSIBLE SCENARIO. POPS STILL SEEM SUSPECT WITH LITTLE IN THE WAY OF
ORGANIZED FLOW INTERACTING OVER THE WEDGE...SO THE LINGERING SLIGHT
CHANCES WERE CHANGED LITTLE.
THE GFS IS MORE AGGRESSIVE IN BRINGING A MOIST OCCLUDED FRONT TO THE
MTNS BY 12Z WED THAN THE ECMWF. THE EC DOES EVENTUALLY BRING THE
FRONT TO THE AREA LATE IN THE DAY...BUT BOTH MODELS CUT OFF THE GOM
MOISTURE FLUX WITH LLVL RIDGING FROM THE WEST. WITH THE MAIN LARGE
SCALE FORCING SHIFTED NORTH...WILL COUNT ON VERY LITTLE IMPACT AS
FAR A PRECIP COVERAGE GOES. FOR NOW...SLIGHT CHANCES WILL
REMAIN...BUT THIS COULD BE INCREASED ONCE BETTER DATA IS GLEANED ON
THIS SYSTEM.
THE NEXT SYSTEM TO THINK ABOUT WILL BE THU/FRI...AS THE GFS INSISTS
ON A MOIST NW FLOW EVENT...YET THE EC REMAINS DRY AND LOW KEY ON THE
KINEMATIC SETUP. THE GFS AS MENTIONED EARLIER IS BRINGING IN A MUCH
STRONGER REINFORCING POLAR VORTEX INTO THE GLAKES LOW...ABOUT TWICE
AS STRONG PVU/WISE THAN THE ECMWF. THIS SEEMS A LITTLE TOO STRONG
FOR THIS TIME OF YEAR...AND FOR NOW WILL SIDE WITH THE MORE
CONSERVATIVE ECMWF ON THIS ONE. THUS...MINIMAL POPS AND AN ALL RAIN
P/TYPE ARE ADVERTISED FOR THAT PERIOD.
OTHER THAN THE LOWER THAN NORMAL POPS EXPECTED TUE....MAX TEMPS
SHOULD REBOUND RATHER NICELY WED THROUGH FRI. INCREASED INSOLATION
AND A WAA FLOW WILL ENABLE MAXES AT OR PERHAPS A COUPLE DEGREES
ABOVE NORMAL. THE NC MTNS WILL BE TRICKERY FRI...AS IT/S PROBABLE
THAT CAA ASSOCIATED WITH THE PASSING VORTEX TO THE NORTH LOWERS
TEMPS THROUGHOUT THE DAY. YET FOR NOW...WILL ONLY GO A COUPLE
DEGREES BELOW NORMAL WITH SO MUCH UNCERTAINTY AND POOR CONTINUITY
DISPLAYED BY THE GUIDANCE.
&&
.AVIATION /04Z SUNDAY THROUGH THURSDAY/...
AT KCLT AND KHKY...EXPECT VFR CONDITIONS TO PREVAIL THROUGH MOST...
IF NOT ALL...THE TAF PERIOD. MODEL GUIDANCE HAS BEEN SLOW TO DEVELOP
THE LOW CLOUDS AND PRECIP ASSOCIATED WITH THE APPROACHING LOW. AT
THIS POINT...IT APPEARS THAT MOISTURE WILL GRADUALLY DEEPEN FROM THE
TOP DOWN ON SUNDAY...SUCH THAT A MID LEVEL CEILING SHOULD BE PRESENT
SUNDAY MORNING...BUT THAT LOW CLOUDS WILL NOT ARRIVE UNTIL THE EARLY
EVENING. ALTHOUGH IT IS CERTAINLY POSSIBLE THAT MVFR CONDITIONS WILL
DEVELOP BEFORE THE END OF THE TAF PERIOD...IT REMAINS MORE LIKELY
THAT THEY WILL HOLD OFF UNTIL RIGHT AROUND SUNSET SUNDAY...SO RATHER
THAN INCLUDE ANOTHER FM GROUP I DECIDED TO LEAVE IT OUT FOR THIS
ISSUANCE. WINDS SHOULD REMAIN NORTHEAST THROUGH THE PERIOD.
ELSEWHERE...THIS WILL NOT BE THE CASE. ENOUGH LOW LEVEL UPGLIDE
SHOULD DEVELOP IN THE AFTERNOON TO FORCE THE DEVELOPMENT OF LIGHT
PRECIP. ONCE THAT HAPPENS...SOME TIME AFTER 18Z...THE PRECIP SHOULD
BRING CLOUD BASES DOWN INTO THE MVFR RANGE. RAIN SHOULD BE LIGHT
ENOUGH INITIALLY SO AS TO NOT REDUCE THE VISIBILITY IN MOST
LOCATIONS...THE EXCEPTION BEING KAND WHERE MORE SIGNIFICANT PRECIP
SHOULD ARRIVE FIRST. STILL THINK IFR CONDITIONS WILL HOLD OFF UNTIL
AFTER THE END OF THE TAF PERIOD.
OUTLOOK...CEILING AND VISIBILITY SHOULD COME CRASHING DOWN TO IFR
AND LIFR SUNDAY NIGHT AS MAIN PRECIP AREA MOVES THROUGH. ONCE
ESTABLISHED...THE COLD AIR DAMMING WEDGE WILL PERSIST THROUGH MONDAY
NIGHT WITH WIDESPREAD IFR CONDITIONS. THE MODEL GUIDANCE SHOWS
IMPROVEMENT TUESDAY BUT MOST LIKELY AT BEST MVFR SHOULD BE EXPECTED
UNTIL WEDNESDAY.
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...PAT
NEAR TERM...MCAVOY/PM
SHORT TERM...CSH
LONG TERM...SBK
AVIATION...PM
000
FXUS62 KCHS 220210
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
910 PM EST SAT NOV 21 2009
.SYNOPSIS...
HIGH PRESSURE WILL REMAIN NORTH OF THE REGION THROUGH TONIGHT. AN
AREA OF LOW PRESSURE WILL TRACK ALONG THE GULF COAST STATES AND
INTO THE ATLANTIC OFF THE SOUTHEAST GEORGIA COAST SUNDAY NIGHT AND
MONDAY...THEN MOVE NORTHEAST ALONG THE EASTERN SEABOARD. A HIGH
PRESSURE WEDGE WILL THEN DOMINATE INTO MID WEEK. LOW PRESSURE WILL
PASS OFF THE SOUTHEAST U.S. COAST ON THURSDAY...THEN WILL BE
FOLLOWED BY COLDER HIGH PRESSURE FROM THE WEST INTO THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
A 1007 MB LOW IS FOUND ALONG THE SOUTHERN COAST OF LA...MOVING
SLOWLY EASTWARD...WHILE 1025 MB HIGH IS CENTERED OVER LAKE ERIE
AND IS WEDGING SOUTH INTO NORTHERN FLORIDA. THE CENTER OF THE HIGH
WILL SHIFT EASTWARD THROUGH THE NIGHT...WITH THE WEDGE BECOMING
FURTHER ESTABLISHED ACROSS THE AREA AS RAINS START BREAKING OUT
ACROSS SOUTHERN GA IN ASSOCIATION WITH A DEVELOPING WARM FRONT TO
THE SOUTH AND SHORT WAVES MOVING NE FROM THE GULF. AS THE WEDGE
STRENGTHENS AND ISENTROPIC LIFT INCREASES WE LOOK FOR AN INCREASE
IN VERTICAL MOISTURE THROUGH THE NIGHT...MAINLY FAR SOUTH...AS
PWATS RISE TO 1-1.25 INCHES SOUTH OF I-16 IN SE GA LATE. GIVEN
THAT THE LEADING EDGE OF THE PRECIP IS ALREADY A LITTLE FURTHER NE
THAN MODEL GUIDANCE DEPICTS...I FEEL COMPELLED TO ADD AT LEAST
SMALL POPS TO FAR SW ZONES LATE TONIGHT...BEGINNING AROUND 4 AM.
CLOUD COVER HAS DISPERSED A BIT SINCE THIS AFTERNOON IN SOME
AREAS...AND HAS ALLOWED FOR TEMPS TO FALL CLOSE TO OUR EARLIER MIN
TEMP FORECAST. BUT WITH CONSIDERABLE MID AND HIGH LEVEL CLOUDINESS
JUST UPSTREAM...TEMP FALL WILL SLOW OR EVEN REVERSE OVERNIGHT. WE
WILL HOWEVER TWEAK TEMPS DOWN INTO THE UPPER 40S AND LOWER 50S
MOST INLAND LOCATIONS...BUT HOLDING IN THE MID AND UPPER 50S
CLOSER TO THE COAST WITH MODERATE NE WINDS DEVELOPING.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/...
A COASTAL TROUGH WILL FURTHER STRENGTHEN OFF THE NC/SC COAST
SUNDAY MORNING...INCREASING ISENTROPIC ASCENT FROM THE E.
MEANWHILE THE RESIDUAL GULF LOW WILL MOVE INTO THE FL
PANHANDLE...ADVECTING QUITE A BIT OF LOW-LEVEL MOISTURE INTO
SOUTHEAST GA AND CENTRAL SC. RAIN SHOULD OVERSPREAD THE ENTIRE
AREA BY LATE MORNING. WE LEFT ISOLATED THUNDERSTORMS ACROSS FAR
SOUTHEASTERN PORTIONS IN THE AFTERNOON DUE TO A SLUG OF 6C
700-500 MB LAPSE RATES PROGGED TO TREK THROUGH. COLD ADVECTION AND
EVAPORATIONAL COOLING WILL KEEP TEMPERATURES FROM INCREASING VERY
MUCH AFTER DAYBREAK. HIGHS WILL PROBABLY NOT GET ABOVE 60F.
&&
.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
GUIDANCE IS IN GOOD AGREEMENT EJECTING WEAKENING SURFACE LOW
PRESSURE OFF THE GEORGIA COAST SUNDAY NIGHT...THEN TRACKING IT
NORTHEAST ALONG THE CAROLINA COAST INTO MONDAY. AS THIS
OCCURS...OVERRUNNING PRECIPITATION WILL ALLOW A HIGH PRESSURE WEDGE
TO BECOME SOLIDLY ENTRENCHED TO THE LEE OF THE APPALACHIANS AS THE
PARENT HIGH STRENGTHENS OVER NEW ENGLAND. THERE IS SOME UNCERTAINTY
AS TO HOW QUICKLY THE WIDESPREAD RAIN WILL TAPER OFF FROM THE
SOUTHWEST SUNDAY NIGHT...AND SOME CONSIDERATION NEEDS TO BE GIVEN TO
THE NAM WHICH SHOWS A DRY SLOT DEVELOPING OVER THE AREA. AS A
RESULT...THE FORECAST WILL SHOW CATEGORICAL RAIN CHANCES TOWARD THE
SANTEE RIVER DECREASING TO ONLY A CHANCE OF RAIN TOWARD THE ALTAMAHA
RIVER SUNDAY EVENING. RAIN CHANCES LATE SUNDAY NIGHT WILL CONTINUE
TO DIMINISH AS THE DEEPEST MOISTURE SHIFTS NORTH AND EAST OF THE
AREA. AS FOR MONDAY...DEEP MOISTURE WILL BE LACKING BUT PLENTY OF
LOW LEVEL MOISTURE WITHIN THE WEDGE COULD SUPPORT A SLIGHT CHANCE OF
LIGHT RAIN AND/OR DRIZZLE ACROSS THE AREA. TEMPERATURES WILL ALSO BE
SEVERELY IMPACTED BY THE WEDGE...AND GUIDANCE APPEARS MUCH TOO WARM
GIVEN THE EXPECTED SCENARIO...THEREFORE WILL FORECAST HIGHS IN THE
MID 50S WELL INLAND TO AROUND 60 TOWARD THE COAST ON MONDAY.
THE HIGH PRESSURE WEDGE SHOULD PERSIST INTO TUESDAY...BEFORE
GRADUALLY ERODING AS THE PARENT HIGH SHIFTS OFF THE NEW ENGLAND
COAST. ABUNDANT LOW LEVEL MOISTURE WILL KEEP CONSIDERABLE CLOUDINESS
IN PLACE...ALONG WITH THE POTENTIAL FOR AT LEAST PATCHY DRIZZLE.
HIGH TEMPERATURES TUESDAY MAY MODERATE SOME...BUT SHOULD REMAIN
BELOW NORMAL AND WELL BELOW WHAT GUIDANCE SUGGESTS.
WEDNESDAY WILL BE A TRANSITION DAY...WITH DRY CONDITIONS AND NEAR
NORMAL TEMPERATURES EXPECTED. LOW PRESSURE IS EXPECTED TO TRACK
OFFSHORE ALONG THE SOUTHEAST U.S. COAST WEDNESDAY NIGHT INTO
THURSDAY...BUT THERE IS SOME MODEL DISAGREEMENT AS TO HOW FAR
OFFSHORE. THEREFORE...WILL SHOW SOME ISOLATED SHOWERS IN THE
FORECAST FOR WEDNESDAY NIGHT. COOL AND DRY HIGH PRESSURE WILL THEN
BUILD FROM THE WEST LATE IN THE WORK WEEK THROUGH THE FIRST PART OF
THE WEEKEND.
&&
.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
KCHS...HIGH PRESSURE WEDGE HOLDS IN PLACE TONIGHT WITH
ANTICYCLONIC FLOW...AND ONLY LIMITED MOISTURE TO BE FOUND IN
PLACE. THUS WE HAVE MAINTAINED VFR WEATHER THROUGH SUNDAY MORNING.
HOWEVER...SHORT WAVE NOW MOVING INTO THE NE GULF OF MEXICO WILL
MOVE THROUGH AFTER DAYBREAK AND RESULT IN SOME LIGHT RAINS
DEVELOPING AROUND 14Z...AND ALSO FOR A LOWERING OF THE CIGS TO
AROUND 5K FEET. THE COMBINATION OF INCREASING LOW LEVEL
CONVERGENCE...ISENTROPIC LIFT AND SHORT WAVES ALOFT WILL PRODUCE A
HEAVIER AND STEADIER RAIN OVERSPREADING THE AREA DURING THE
AFTERNOON...AND WITH IT OUR CONDITIONS WILL DROP TO MVFR AT 18Z
AND TO IFR AT 22Z. THE RISK OF WIND SHEAR IS MARGINAL BUT DOES
BEAR WATCHING SUNDAY AFTERNOON.
KSAV...THE HIGH PRESSURE WEDGE AND ITS RESULTING ANTICYCLONIC FLOW
EARLY TONIGHT WILL GIVE WAY TO A SHORT WAVE AND MORE CYCLONIC
CURVATURE OF THE ISOBARS LATE TONIGHT. THIS ALLOWS FOR A STEADY
MOISTENING OF THE LOWER LEVELS AND EVENTUALLY LIGHT RAINS AND A
LOWERING OF THE CIGS TO OCCUR...FALLING TO MVFR AT 14Z. A MORE
SUBSTANTIAL INCREASE IN OVERALL MOISTURE AND LOW LEVEL CONVERGENCE
AND ISENTROPIC LIFT FORMS FOR THE AFTERNOON...AND IFR WEATHER WILL
PREVAIL FROM 18Z ONWARDS. LATER SHIFTS WILL NEED TO KEEP WATCH FOR
A LITTLE ELEVATED CONVECTION THAT WILL ATTEMPT TO DEVELOP LATE
SUNDAY AS SHOWALTER INDICES DROP TO -1 OR -2 AND MID LEVEL LAPSE
RATES APPROACH 6C/KM. ALSO...THE RISK OF WIND SHEAR IS MARGINAL BUT
DOES BEAR WATCHING DURING SUNDAY.
EXTENDED AVIATION OUTLOOK...MVFR OR LOWER CONDITIONS ARE LIKELY
SUNDAY NIGHT THROUGH TUESDAY. VFR CONDITIONS MAY RETURN ON
WEDNESDAY.
&&
.MARINE...
THERE WILL CONTINUE TO BE ENOUGH PINCHING OF THE PRESSURE GRADIENT
TONIGHT BETWEEN THE INLAND HIGH PRESSURE WEDGE AND THE DEVELOPING
WARM FRONT TO THE SOUTH...THAT 20 KT WINDS ARE COMMON ACROSS THE
ATLANTIC WATERS TONIGHT. EVEN CHARLESTON HARBOR WILL HAVE A SOLID
15 KT. SEAS WILL BUILD TO 5 OR 6 FEET WITHIN 20 NM OF THE
COAST...AND UP TO 6 OR 7 FEET ACROSS THE OUTER GA WATERS. THE
WATERS WILL BE QUITE AGITATED WITH THE NE OR NORTH WIND
WAVES...AND A 2-4 FOOT SWELL WAVE FROM THE EAST EVERY 8-9 SECONDS.
WE WILL CONTINUE THE SCA/S FOR AMZ350-352-374...AND CAREFULLY KEEP
WATCH ON AMZ330-354 SHOULD THE PINCHING GET STRONGER AND INDUCE
HIGHER WINDS/SEAS.
THE PRESSURE GRADIENT WILL INCREASE FURTHER SUNDAY AS THE WEDGE OF
HIGH PRESSURE STRENGTHENS FROM THE NORTH WHILE AN APPROACHING
UPPER TROUGH STRENGTHENS A TROUGH AT THE SURFACE. 20 OR 25 KT
WINDS WILL BE COMMON...WHILE SEAS WILL BE AT LEAST AS HIGH AS 5 TO
7 FEET. SCA/S MAY BE NEEDED FOR AMZ354 AND AMZ330...OTHERWISE
SOLID SCA WILL OCCUR ELSEWHERE.
CONDITIONS WILL BEGIN TO SLOWLY IMPROVE OVER THE WATERS SUNDAY
NIGHT DUE TO A WEAKENING SURFACE PRESSURE GRADIENT AS LOW PRESSURE
EJECTS OFF THE GEORGIA COAST AND TRACKS JUST OFF THE COAST OF
SOUTH CAROLINA. WINDS AND SEAS SHOULD FALL BELOW SMALL CRAFT
ADVISORY CRITERIA OVER THE FAR SOUTHERN SOUTH CAROLINA NEAR SHORE
WATERS SUNDAY EVENING...THEN OVER THE REMAINING SOUTH CAROLINA
NEAR SHORE WATERS AND OUTER GEORGIA WATERS BY LATE SUNDAY NIGHT. A
NORTHERLY FLOW WILL THEN PERSIST THROUGH MID WEEK...WITH SPEEDS 15
KT OR LESS. AN STRENGTHENING OFFSHORE FLOW IS EXPECTED ON THURSDAY
AS STRONG COLD AIR ADVECTION DEVELOPS OVER THE WATERS.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL MIDNIGHT EST SUNDAY NIGHT FOR
AMZ352.
SMALL CRAFT ADVISORY UNTIL 5 AM EST MONDAY FOR AMZ350-374.
&&
$$
33
000
FXUS62 KGSP 220029
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
729 PM EST SAT NOV 21 2009
.SYNOPSIS...
HIGH PRESSURE OVER THE REGION WILL SHIFT NORTH OVER THE WEEKEND.
THIS WILL ALLOW A LOW PRESSURE SYSTEM TO MOVE EAST ALONG THE GULF
COAST THEN NORTH ALONG THE CAROLINA COAST SUNDAY THROUGH MONDAY.
THE LOW IS EXPECTED TO REACH THE NEW ENGLAND COAST BY TUESDAY AS
WEAK HIGH PRESSURE REMAINS OVER THE SOUTHEAST STATES. ANOTHER COLD
FRONT OR COASTAL LOW COULD MOVE INTO THE AREA BY THE MIDDLE OF NEXT
WEEK.
&&
.NEAR TERM /THROUGH SUNDAY/...
SATELLITE IMAGERY SHOWS ONLY HIGH THIN CLOUDS ACROSS THE WESTERN
CAROLINAS AT SUNSET. THIS HAS ALLOWED TEMPS TO DROP QUICKER THAN
EXPECTED. WILL TAKE THIS OPPORTUNITY TO ADJUST TEMP TREND...BUT MIN
TEMP STILL LOOKS OKAY. HAVE ALSO DELAYED THE CLOUD UP UNTIL LATER
TONIGHT AS WELL. HAVE ALSO ADJUSTED POP FOR SUNDAY BASED ON THE 15Z
SREF BECAUSE IT WAS PREFERRED BY THE PREVIOUS SHIFT.
CONFLUENT FLOW OFF THE NEW ENGLAND COAST WILL GRADUALLY STRENGTHEN
SFC HIGH PRESSURE OVER THE MID ATLANTIC STATES THROUGH SUNDAY. THE
MORNING UPPER AIR SHOWED VERY DRY AIR DOWN ALONG THE GULF COAST. FOR
EXAMPLE...THE TALLAHASSEE RAOB HAD A 40 DEGREE DEWPOINT DEPRESSION
AT 850 MB. WITH THIS MUCH DRY AIR TO THE SOUTH...AND WITH A
DEVELOPING CLASSICAL COLD AIR DAMMING EVENT...IT/S NOT SURPRISING
THAT THE MODELS HAVE BEEN DELAYING THE ONSET OF PCPN OVER THE PAST
SEVERAL RUNS. AT LEAST THE GFS HAS TONED DOWN THE POT VORT MAXES AND
HEAVY PCPN THAT IT HAD BEEN DRIVING ACROSS THE HEART OF THE WEDGE
RIDGE. THIS SEEMS MORE REALISTIC AS QPF SHOULD BE FAIRLY LIGHT
WITH THE LLVL DRY AIR AND THE WEAKENING SRN STREAM SYSTEM. THE BEST
CHANCES FOR HEAVY RAIN WILL BE ALONG THE COASTAL FRONT...WELL TO OUR
SOUTH.
OVERALL...THE SREF SEEMS TO HAVE DONE THE BEST JOB OF HANDLING THE
EVOLUTION OF THE GULF COAST LOW AND PCPN DISTRIBUTION SO FAR. I/VE
FOLLOWED IT FAIRLY CLOSELY FOR THE TIMING OF PCPN. THIS MEANS A DRY
FORECAST TONIGHT. PCPN SHOULD OVERSPREAD THE REGION FROM THE
SOUTHWEST ON SUNDAY...THOUGH I DON/T SEE ANYTHING FALLING NORTH OF
GREENVILLE UNTIL THE AFTERNOON HOURS. I RAISED MAX TEMPS A COUPLE
CATEGORIES OVER THE NE ZONES WHERE THINNER CLOUD COVER EARLY IN THE
DAY WILL RESULT IN A LITTLE MORE WARMING THAN ORIGINALLY EXPECTED. I
FOLLOWED A MET/MAV BLEND AND WE MATCH UP WELL WITH THE NEIGHBORS.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/...
AS OF 130 PM SATURDAY...NOT THAT THERE IS A GREAT DEAL OF CONFIDENCE
WITH REGARDS TO THE SPECIFICS OF THE SUNDAY NIGHT FCST...BUT LIKELY
SOME DEGREE OF DEEP RH AND ESE FLOW ABOVE LINGERING WEDGE WILL REMAIN
ALL NIGHT. SENSIBLE WX IS STILL EXPECTED TO BE DAMP WITH RAINY AND
DRIZZLY PERIODS...ALTHOUGH PCPN TOTALS WILL BE MODERATE AT WORST.
CONFIDENCE INCREASING THAT DAMMING REGIME WILL REMAIN THRU
MONDAY...ALTHOUGH FORCING FOR ADDITIONAL PCPN WILL WANE...EVENTUALLY
JUST BEING FORCED BY SOME DEGREE OF WAA/EASTERLY FLOW JUST ABV SFC.
EVEN THE MILDER 12 UTC MET NUMBERS...WHICH WILL PROBABLY BE TOO WARM
ANYWAY...SUPPORT NOTABLE LOWERING OF GOING MAX TEMPS. GIVEN THE
WEAKENING OF THE LLVL FLOW MONDAY NIGHT AND RESIDUAL WEAK SFC
RIDGING...THERE SEEMS TO BE LITTLE HOPE OF SCOURING...SO WILL PLAN
ON LEAVING OVC CONDS WITH SPOTTY AREAS OF LIGHT RAIN/DRIZZLE...
ESPECIALLY ALONG AND EAST OF THE ESCARPMENT WHERE WEAK LLVL
EASTERLY FLOW WILL CONTINUE TO LIFT SHALLOW MOISTURE.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
AS OF 145 PM SATURDAY...NOT MUCH AGREEMENT IS SEEN IN THE OP MODELS
WITH RESPECT TO AMOUNT OF DEEPENING OF THE MID WEEK CUT OFF LOW AND
THE LEVEL OF MOISTURE AVAILABLE FOR THE OCCLUDED FRONT TO WORK WITH
ONCE IT REACHES THE CWFA WED MORNING. EVEN LESS AGREEMENT IS SEEN
BETWEEN THE GFS AND THE ECMWF ON THU/FRI WITH THE POLAR VORTEX
REINFORCING THE GLAKES LOW AND THE EVENTUAL TRACK AND SPEED OF THE
LARGE SCALE PATTERN. THE GFS H5 ENS MEMBERS SHOW THE HIGHEST SPREAD
EARLY FRI MORNING WITH ABOUT 8 DM OF UNCERTAINTY ASSOCIATED WITH
THE HEIGHT FIELD...LENDING LOW CONFIDENCE TOWARD THE SETUP FOR A
POSSIBLE MINIMAL NW FLOW EVENT.
NOT MANY CHANGES HAVE BEN MADE TO THE GOING FORECAST WITH LITTLE
CONFIDENCE HAD BOTH IN THE OP MODELS AND HPC GUIDANCE. SOME DECENT
AGREEMENT IS SEEN TUE WITH THE SLOWER BREAKDOWN OF THE SFC WEDGE.
MODEL SOUNDINGS INDICATE RATHER THICK STRATUS HANGING ON THROUGHOUT
THE DAY AND VERY LOW WINDS IN THE BL. SO...MAX TEMP GUIDANCE HAS
BEEN CUT BACK A CAT OR SO OUTSIDE THE MTNS TO ACCOUNT FOR THIS
POSSIBLE SCENARIO. POPS STILL SEEM SUSPECT WITH LITTLE IN THE WAY OF
ORGANIZED FLOW INTERACTING OVER THE WEDGE...SO THE LINGERING SLIGHT
CHANCES WERE CHANGED LITTLE.
THE GFS IS MORE AGGRESSIVE IN BRINGING A MOIST OCCLUDED FRONT TO THE
MTNS BY 12Z WED THAN THE ECMWF. THE EC DOES EVENTUALLY BRING THE
FRONT TO THE AREA LATE IN THE DAY...BUT BOTH MODELS CUT OFF THE GOM
MOISTURE FLUX WITH LLVL RIDGING FROM THE WEST. WITH THE MAIN LARGE
SCALE FORCING SHIFTED NORTH...WILL COUNT ON VERY LITTLE IMPACT AS
FAR A PRECIP COVERAGE GOES. FOR NOW...SLIGHT CHANCES WILL
REMAIN...BUT THIS COULD BE INCREASED ONCE BETTER DATA IS GLEANED ON
THIS SYSTEM.
THE NEXT SYSTEM TO THINK ABOUT WILL BE THU/FRI...AS THE GFS INSISTS
ON A MOIST NW FLOW EVENT...YET THE EC REMAINS DRY AND LOW KEY ON THE
KINEMATIC SETUP. THE GFS AS MENTIONED EARLIER IS BRINGING IN A MUCH
STRONGER REINFORCING POLAR VORTEX INTO THE GLAKES LOW...ABOUT TWICE
AS STRONG PVU/WISE THAN THE ECMWF. THIS SEEMS A LITTLE TOO STRONG
FOR THIS TIME OF YEAR...AND FOR NOW WILL SIDE WITH THE MORE
CONSERVATIVE ECMWF ON THIS ONE. THUS...MINIMAL POPS AND AN ALL RAIN
P/TYPE ARE ADVERTISED FOR THAT PERIOD.
OTHER THAN THE LOWER THAN NORMAL POPS EXPECTED TUE....MAX TEMPS
SHOULD REBOUND RATHER NICELY WED THROUGH FRI. INCREASED INSOLATION
AND A WAA FLOW WILL ENABLE MAXES AT OR PERHAPS A COUPLE DEGREES
ABOVE NORMAL. THE NC MTNS WILL BE TRICKERY FRI...AS IT/S PROBABLE
THAT CAA ASSOCIATED WITH THE PASSING VORTEX TO THE NORTH LOWERS
TEMPS THROUGHOUT THE DAY. YET FOR NOW...WILL ONLY GO A COUPLE
DEGREES BELOW NORMAL WITH SO MUCH UNCERTAINTY AND POOR CONTINUITY
DISPLAYED BY THE GUIDANCE.
&&
.AVIATION /01Z SUNDAY THROUGH THURSDAY/...
AT KCLT AND KHKY...EXPECT VFR CONDITIONS TO PREVAIL THROUGH MOST...
IF NOT ALL...THE TAF PERIOD. MODEL GUIDANCE HAS BEEN SLOW TO DEVELOP
THE LOW CLOUDS AND PRECIP ASSOCIATED WITH THE APPROACHING LOW. AT
THIS POINT...IT APPEARS THAT MOISTURE WILL GRADUALLY DEEPEN FROM THE
TOP DOWN ON SUNDAY...SUCH THAT A MID LEVEL CEILING SHOULD BE PRESENT
SUNDAY MORNING...BUT THAT LOW CLOUDS WILL NOT ARRIVE UNTIL THE EARLY
EVENING. ALTHOUGH IT IS CERTAINLY POSSIBLE THAT MVFR CONDITIONS WILL
DEVELOP BEFORE THE END OF THE TAF PERIOD...IT REMAINS MORE LIKELY
THAT THEY WILL HOLD OFF UNTIL RIGHT AROUND SUNSET SUNDAY...SO RATHER
THAN INCLUDE ANOTHER FM GROUP I DECIDED TO LEAVE IT OUT FOR THIS
ISSUANCE. WINDS SHOULD REMAIN NORTHEAST THROUGH THE PERIOD.
ELSEWHERE...THIS WILL NOT BE THE CASE. ENOUGH LOW LEVEL UPGLIDE
SHOULD DEVELOP IN THE AFTERNOON TO FORCE THE DEVELOPMENT OF LIGHT
PRECIP. ONCE THAT HAPPENS...SOME TIME AFTER 18Z...THE PRECIP SHOULD
BRING CLOUD BASES DOWN INTO THE MVFR RANGE. RAIN SHOULD BE LIGHT
ENOUGH INITIALLY SO AS TO NOT REDUCE THE VISIBILITY IN MOST
LOCATIONS...THE EXCEPTION BEING KAND WHERE MORE SIGNIFICANT PRECIP
SHOULD ARRIVE FIRST. STILL THINK IFR CONDITIONS WILL HOLD OFF UNTIL
AFTER THE END OF THE TAF PERIOD.
OUTLOOK...CEILING AND VISIBILITY SHOULD COME CRASHING DOWN TO IFR
AND LIFR SUNDAY NIGHT AS MAIN PRECIP AREA MOVES THROUGH. ONCE
ESTABLISHED...THE COLD AIR DAMMING WEDGE WILL PERSIST THROUGH MONDAY
NIGHT WITH WIDESPREAD IFR CONDITIONS. THE MODEL GUIDANCE SHOWS
IMPROVEMENT TUESDAY BUT MOST LIKELY AT BEST MVFR SHOULD BE EXPECTED
UNTIL WEDNESDAY.
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...PAT
NEAR TERM...MCAVOY/PM
SHORT TERM...CSH
LONG TERM...SBK
AVIATION...PM
000
FXUS62 KCHS 212336
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
636 PM EST SAT NOV 21 2009
.SYNOPSIS...
HIGH PRESSURE WILL REMAIN NORTH OF THE REGION THROUGH TONIGHT. AN
AREA OF LOW PRESSURE WILL TRACK ALONG THE GULF COAST STATES AND
INTO THE ATLANTIC OFF THE SOUTHEAST GEORGIA COAST SUNDAY AND
SUNDAY NIGHT...THEN MOVE NORTHEAST ALONG THE EASTERN SEABOARD. A
HIGH PRESSURE WEDGE WILL THEN DOMINATE INTO MID WEEK. LOW PRESSURE
WILL PASS OFF THE SOUTHEAST U.S. COAST ON THURSDAY...THEN WILL BE
FOLLOWED BY HIGH PRESSURE FROM THE WEST INTO THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
A VERTICALLY-STACKED LOW PRESSURE SYSTEM EXISTS OVER SOUTHERN
LOUISIANA EARLY THIS AFTERNOON. AS THE SURFACE LOW CONTINUES TO
OCCLUDE AND WEAKEN...ONLY SLOW MOVEMENT IS EXPECTED TO THE ENE
TONIGHT. THE PRIMARY DRIVER FOR OUR WEATHER WILL BE SECONDARY
CYCLOGENESIS OFF THE GA/SC COAST LATE TONIGHT INTO SUNDAY AS A
BAROCLINIC ZONE STRENGTHENS AHEAD OF THE UPPER TROUGH. QUITE A BIT
OF DRY AIR WILL PERSIST IN THE LOWER LEVELS AS HIGH PRESSURE
CONTINUES TO WEDGE DOWN THE EASTERN SEABOARD. MOSTLY MID AND HIGH
CLOUDS WILL STREAM ACROSS FROM THE SW THIS EVENING BEFORE LOWER
LEVEL CLOUDINESS AND SOME RAIN SHOWERS MOVE IN LATE. WE CONTINUED
THE TREND OF A LATER ARRIVAL TIME FOR PRECIPITATION WITH POPS
BEGINNING AT 5 AM SUNDAY. TEMPS WILL DROP NO LOWER THAN THE 50S
OVERNIGHT DUE TO THE CLOUDY SKIES AND 3-5 KTS OF WIND.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/...
A COASTAL TROUGH WILL FURTHER STRENGTHEN OFF THE NC/SC COAST
SUNDAY MORNING...INCREASING ISENTROPIC ASCENT FROM THE E.
MEANWHILE THE RESIDUAL GULF LOW WILL MOVE INTO THE FL
PANHANDLE...ADVECTING QUITE A BIT OF LOW-LEVEL MOISTURE INTO
SOUTHEAST GA AND CENTRAL SC. RAIN SHOULD OVERSPREAD THE ENTIRE
AREA BY LATE MORNING. WE LEFT ISOLATED THUNDERSTORMS ACROSS FAR
SOUTHEASTERN PORTIONS IN THE AFTERNOON DUE TO A SLUG OF 6C
700-500 MB LAPSE RATES PROGGED TO TREK THROUGH. COLD ADVECTION AND
EVAPORATIONAL COOLING WILL KEEP TEMPERATURES FROM INCREASING VERY
MUCH AFTER DAYBREAK. HIGHS WILL PROBABLY NOT GET ABOVE 60F.
&&
.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
GUIDANCE IS IN GOOD AGREEMENT EJECTING WEAKENING SURFACE LOW
PRESSURE OFF THE GEORGIA COAST SUNDAY NIGHT...THEN TRACKING IT
NORTHEAST ALONG THE CAROLINA COAST INTO MONDAY. AS THIS
OCCURS...OVERRUNNING PRECIPITATION WILL ALLOW A HIGH PRESSURE WEDGE
TO BECOME SOLIDLY ENTRENCHED TO THE LEE OF THE APPALACHIANS AS THE
PARENT HIGH STRENGTHENS OVER NEW ENGLAND. THERE IS SOME UNCERTAINTY
AS TO HOW QUICKLY THE WIDESPREAD RAIN WILL TAPER OFF FROM THE
SOUTHWEST SUNDAY NIGHT...AND SOME CONSIDERATION NEEDS TO BE GIVEN TO
THE NAM WHICH SHOWS A DRY SLOT DEVELOPING OVER THE AREA. AS A
RESULT...THE FORECAST WILL SHOW CATEGORICAL RAIN CHANCES TOWARD THE
SANTEE RIVER DECREASING TO ONLY A CHANCE OF RAIN TOWARD THE ALTAMAHA
RIVER SUNDAY EVENING. RAIN CHANCES LATE SUNDAY NIGHT WILL CONTINUE
TO DIMINISH AS THE DEEPEST MOISTURE SHIFTS NORTH AND EAST OF THE
AREA. AS FOR MONDAY...DEEP MOISTURE WILL BE LACKING BUT PLENTY OF
LOW LEVEL MOISTURE WITHIN THE WEDGE COULD SUPPORT A SLIGHT CHANCE OF
LIGHT RAIN AND/OR DRIZZLE ACROSS THE AREA. TEMPERATURES WILL ALSO BE
SEVERELY IMPACTED BY THE WEDGE...AND GUIDANCE APPEARS MUCH TOO WARM
GIVEN THE EXPECTED SCENARIO...THEREFORE WILL FORECAST HIGHS IN THE
MID 50S WELL INLAND TO AROUND 60 TOWARD THE COAST ON MONDAY.
THE HIGH PRESSURE WEDGE SHOULD PERSIST INTO TUESDAY...BEFORE
GRADUALLY ERODING AS THE PARENT HIGH SHIFTS OFF THE NEW ENGLAND
COAST. ABUNDANT LOW LEVEL MOISTURE WILL KEEP CONSIDERABLE CLOUDINESS
IN PLACE...ALONG WITH THE POTENTIAL FOR AT LEAST PATCHY DRIZZLE.
HIGH TEMPERATURES TUESDAY MAY MODERATE SOME...BUT SHOULD REMAIN
BELOW NORMAL AND WELL BELOW WHAT GUIDANCE SUGGESTS.
WEDNESDAY WILL BE A TRANSITION DAY...WITH DRY CONDITIONS AND NEAR
NORMAL TEMPERATURES EXPECTED. LOW PRESSURE IS EXPECTED TO TRACK
OFFSHORE ALONG THE SOUTHEAST U.S. COAST WEDNESDAY NIGHT INTO
THURSDAY...BUT THERE IS SOME MODEL DISAGREEMENT AS TO HOW FAR
OFFSHORE. THEREFORE...WILL SHOW SOME ISOLATED SHOWERS IN THE
FORECAST FOR WEDNESDAY NIGHT. COOL AND DRY HIGH PRESSURE WILL THEN
BUILD FROM THE WEST LATE IN THE WORK WEEK THROUGH THE FIRST PART OF
THE WEEKEND.
&&
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
KCHS...HIGH PRESSURE WEDGE HOLDS IN PLACE TONIGHT WITH
ANTICYCLONIC FLOW...AND ONLY LIMITED MOISTURE TO BE FOUND IN
PLACE. THUS WE HAVE MAINTAINED VFR WEATHER THROUGH SUNDAY MORNING.
HOWEVER...SHORT WAVE NOW MOVING INTO THE NE GULF OF MEXICO WILL
MOVE THROUGH AFTER DAYBREAK AND RESULT IN SOME LIGHT RAINS
DEVELOPING AROUND 14Z...AND ALSO FOR A LOWERING OF THE CIGS TO
AROUND 5K FEET. THE COMBINATION OF INCREASING LOW LEVEL
CONVERGENCE...ISENTROPIC LIFT AND SHORT WAVES ALOFT WILL PRODUCE A
HEAVIER AND STEADIER RAIN OVERSPREADING THE AREA DURING THE
AFTERNOON...AND WITH IT OUR CONDITIONS WILL DROP TO MVFR AT 18Z
AND TO IFR AT 22Z. THE RISK OF WIND SHEAR IS MARGINAL BUT DOES
BEAR WATCHING SUNDAY AFTERNOON.
KSAV...THE HIGH PRESSURE WEDGE AND ITS RESULTING ANTICYCLONIC FLOW
EARLY TONIGHT WILL GIVE WAY TO A SHORT WAVE AND MORE CYCLONIC
CURVATURE OF THE ISOBARS LATE TONIGHT. THIS ALLOWS FOR A STEADY
MOISTENING OF THE LOWER LEVELS AND EVENTUALLY LIGHT RAINS AND A
LOWERING OF THE CIGS TO OCCUR...FALLING TO MVFR AT 14Z. A MORE
SUBSTANTIAL INCREASE IN OVERALL MOISTURE AND LOW LEVEL CONVERGENCE
AND ISENTROPIC LIFT FORMS FOR THE AFTERNOON...AND IFR WEATHER WILL
PREVAIL FROM 18Z ONWARDS. LATER SHIFTS WILL NEED TO KEEP WATCH FOR
A LITTLE ELEVATED CONVECTION THAT WILL ATTEMPT TO DEVELOP LATE
SUNDAY AS SHOWALTER INDICES DROP TO -1 OR -2 AND MID LEVEL LAPSE
RATES APPROACH 6C/KM. ALSO...THE RISK OF WIND SHEAR IS MARGINAL BUT
DOES BEAR WATCHING DURING SUNDAY.
EXTENDED AVIATION OUTLOOK...MVFR OR LOWER CONDITIONS ARE LIKELY
SUNDAY NIGHT THROUGH TUESDAY. VFR CONDITIONS MAY RETURN ON
WEDNESDAY.
&&
.MARINE...
THE PRESSURE GRADIENT SHOULD INCREASE SUBSTANTIALLY TONIGHT INTO
SUNDAY AS A WEDGE OF HIGH PRESSURE STRENGTHENS FROM THE NORTH
WHILE AN APPROACHING UPPER TROUGH STRENGTHENS A TROUGH AT THE
SURFACE. 20-25 KT WINDS MAY DEVELOP ACROSS THE SC NEARSHORE WATERS
LATE TONIGHT INTO SUNDAY WHILE 6 FT SEAS COULD PUSH INTO OUTER
PORTIONS OF THESE ZONES AS WELL. WE HOISTED A SMALL CRAFT ADVISORY
FOR THE SC NEARSHORE WATERS FROM EDISTO SOUTHWARD TO JOIN THE
EXISTING ADVISORIES FOR THE NORTHERN LEG AND THE OFFSHORE GA LEG.
CONDITIONS WILL BEGIN TO IMPROVE OVER THE WATERS SUNDAY NIGHT DUE
TO A WEAKENING SURFACE PRESSURE GRADIENT AS LOW PRESSURE EJECTS
OFF THE GEORGIA COAST AND TRACKS JUST OFF THE COAST OF SOUTH
CAROLINA. WINDS AND SEAS SHOULD FALL BELOW SMALL CRAFT ADVISORY
CRITERIA OVER THE FAR SOUTHERN SOUTH CAROLINA NEAR SHORE WATERS
SUNDAY EVENING...THEN OVER THE REMAINING SOUTH CAROLINA NEAR SHORE
WATERS AND OUTER GEORGIA WATERS BY LATE SUNDAY NIGHT. A NORTHERLY
FLOW WILL THEN PERSIST THROUGH MID WEEK...WITH SPEEDS 15 KT OR
LESS. AN STRENGTHENING OFFSHORE FLOW IS EXPECTED ON THURSDAY AS
STRONG COLD AIR ADVECTION DEVELOPS OVER THE WATERS.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL MIDNIGHT EST SUNDAY NIGHT FOR
AMZ352.
SMALL CRAFT ADVISORY UNTIL 5 AM EST MONDAY FOR AMZ350-374.
&&
$$
33
000
FXUS62 KCAE 212317
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
617 PM EST SAT NOV 21 2009
.SYNOPSIS...
A LOW PRESSURE SYSTEM IN THE NORTHWEST GULF OF MEXICO WILL MOVE
SLOWLY NORTHEAST TO THE FLORIDA PANHANDLE TONIGHT...THEN REFORM
ALONG THE CAROLINA COAST SUNDAY NIGHT. HIGH PRESSURE WILL WEDGE
INTO THE CAROLINAS FROM THE NORTH. THIS PATTERN WILL BRING CLOUDS
AND RAIN TO THE AREA THROUGH MONDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
CLOSED UPPER LOW OVER EAST TEXAS WILL DE-AMPLIFY OVERNIGHT AS IT
MOVES NORTHEAST. SURFACE LOW OVER THE NORTHERN GULF OF MEXICO THIS
AFTERNOON WILL SLOWLY MOVE EAST AS HIGH PRESSURE WEDGES INTO THE
CAROLINAS FROM NORTH. SKIES EXPECTED TO BECOME CLOUDY TONIGHT AS
ISENTROPIC LIFT BEGINS. RAIN SPREADING NORTH FROM THE GULF COAST
STATES MAY REACH THE SAVANNAH RIVER AREA BY DAYBREAK SUNDAY. WENT
WITH CONSENSUS LOWS...RANGING FROM THE MID 40S NORTH TO NEAR 50
SOUTH.
&&
.SHORT TERM /SUNDAY THROUGH TUESDAY/...
MODELS FINALLY IN AGREEMENT WITH STRONG ISENTROPIC LIFT OVER THE
AREA SUNDAY AFTERNOON INTO SUNDAY NIGHT. WEAKENING SHORT WAVE
MOVING OUT OF TEXAS TONIGHT WILL CROSS GA INTO THE CAROLINAS
SUNDAY NIGHT. LOW PRESSURE DEVELOPING ON AN INVERTED TROUGH OFF
THE SC COAST. KEPT CATEGORICAL POPS FOR SUNDAY INTO SUNDAY NIGHT.
RAINFALL AMOUNTS RANGING FROM ONE HALF INCH TO AROUND ONE INCH.
THE SURFACE LOW WILL MOVE AWAY FROM THE COAST MONDAY WITH RAIN
CHANCES DECREASING. KEPT CHANCE OF DRIZZLE IN FOR MONDAY NIGHT
INTO TUESDAY.
SINCE WEDGE PATTERN EXPECTED SUNDAY THROUGH TUESDAY...SHOULD SEE
PLENTY OF CLOUDS. KEPT DAYTIME TEMPERATURES BELOW GUIDANCE. HIGHS
IN THE LOW TO MID 50S (WHICH MAY BE ON THE HIGH SIDE). LITTLE DIURNAL
CHANGE IN TEMPERATURES EXPECTED. LOWS IN THE MID TO UPPER 40S.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
MEDIUM RANGE MODELS DEPICT A SERIES OF MID/UPPER LEVEL LOWS MOVING
ACROSS THE UPPER MIDWEST TO THE EASTERN GREAT LAKES AND
SOUTHEASTERN CANADA TUESDAY NIGHT INTO SATURDAY. ALL IN ALL,
SLIGHT UPPER RIDGING OVER THE SOUTHEAST PART OF THE COUNTRY
TUESDAY IS REPLACED BY A LARGE UPPER TROUGH OVER THE EASTERN
UNITED STATES WEDNESDAY THROUGH FRIDAY. UPPER TROUGH FINALLY MOVES
OFF THE EAST COAST SATURDAY. SURFACE HIGH PRESSURE CENTERED OVER
SOUTHEASTERN CANADA TUESDAY NIGHT RIDGING INTO THE AREA FROM THE
NORTH. SURFACE LOW PRESSURE CROSSING THE GREAT LAKES REGION ON
THANKSGIVING DAY WILL DRAG A COLD FRONT ACROSS THE AREA. MOISTURE
APPEARS LIMITED SINCE THE BEST ISENTROPIC LIFT REMAINS SOUTH AND
EAST OF THE FORECAST AREA. ANY CHANCE FOR RAIN (WHICH IS SLIGHT)
LOOKS LIKE WEDNESDAY INTO THURSDAY MORNING. COOL HIGH PRESSURE
BUILDS IN FOR FRIDAY AND SATURDAY. WILL KEEP THE EXTENDED FORECAST
DRY. SEASONABLY MILD MAX TEMPERATURES WEDNESDAY AND THURSDAY COOL
A FEW DEGREES BELOW NORMAL FOR FRIDAY AND SATURDAY. NIGHTTIME LOWS
IN THE 40S MID-WEEK COOLING TO THE MID AND UPPER 30S BY LATE NEXT
WEEK.
&&
.AVIATION /00Z SUNDAY THROUGH FRIDAY/...
HIGH PRESSURE OVER THE MID-ATLANTIC STATES WILL MOVE OFFSHORE AS A
LOW PRESSURE SYSTEM OVER THE GULF OF MEXICO MOVES NORTHEAST. THIS
LOW WILL TRACK OVER THE SE STATES ON SUNDAY BRINGING RAIN WITH
MVFR/IFR CONDITIONS TO THE AREA. THE TAF PERIOD WILL START OUT VFR
WITH MVFR CIGS DEVELOPING BY AROUND 12Z-14Z WITH SOME SPRINKLES
POSSIBLE BY THEN. CONDITIONS BECOME IFR BY LATE IN THE TAF PERIOD AS
PRECIPITATION SPREADS ACROSS THE REGION SUNDAY AFTERNOON.
EXTENDED AVIATION OUTLOOK...WIDESPREAD MVFR OR IFR CONDITIONS WILL
CONTINUE LATE SUNDAY INTO EARLY MONDAY AS THE LOW PRESSURE SYSTEM
MOVES THROUGH THE AREA. CONDITIONS WILL IMPROVE TO VFR BY MONDAY
AFTERNOON AS THE LOW MOVES OUT OF THE AREA.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
000
FXUS62 KCHS 212056
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
356 PM EST SAT NOV 21 2009
.SYNOPSIS...
HIGH PRESSURE WILL REMAIN NORTH OF THE REGION THROUGH TONIGHT. AN
AREA OF LOW PRESSURE WILL TRACK ALONG THE GULF COAST STATES AND
INTO THE ATLANTIC OFF THE SOUTHEAST GEORGIA COAST SUNDAY AND
SUNDAY NIGHT...THEN MOVE NORTHEAST ALONG THE EASTERN SEABOARD. A
HIGH PRESSURE WEDGE WILL THEN DOMINATE INTO MID WEEK. LOW PRESSURE
WILL PASS OFF THE SOUTHEAST U.S. COAST ON THURSDAY...THEN WILL BE
FOLLOWED BY HIGH PRESSURE FROM THE WEST INTO THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
A VERTICALLY-STACKED LOW PRESSURE SYSTEM EXISTS OVER SOUTHERN
LOUISIANA EARLY THIS AFTERNOON. AS THE SURFACE LOW CONTINUES TO
OCCLUDE AND WEAKEN...ONLY SLOW MOVEMENT IS EXPECTED TO THE ENE
TONIGHT. THE PRIMARY DRIVER FOR OUR WEATHER WILL BE SECONDARY
CYCLOGENESIS OFF THE GA/SC COAST LATE TONIGHT INTO SUNDAY AS A
BAROCLINIC ZONE STRENGTHENS AHEAD OF THE UPPER TROUGH. QUITE A BIT
OF DRY AIR WILL PERSIST IN THE LOWER LEVELS AS HIGH PRESSURE
CONTINUES TO WEDGE DOWN THE EASTERN SEABOARD. MOSTLY MID AND HIGH
CLOUDS WILL STREAM ACROSS FROM THE SW THIS EVENING BEFORE LOWER
LEVEL CLOUDINESS AND SOME RAIN SHOWERS MOVE IN LATE. WE CONTINUED
THE TREND OF A LATER ARRIVAL TIME FOR PRECIPITATION WITH POPS
BEGINNING AT 5 AM SUNDAY. TEMPS WILL DROP NO LOWER THAN THE 50S
OVERNIGHT DUE TO THE CLOUDY SKIES AND 3-5 KTS OF WIND.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/...
A COASTAL TROUGH WILL FURTHER STRENGTHEN OFF THE NC/SC COAST
SUNDAY MORNING...INCREASING ISENTROPIC ASCENT FROM THE E.
MEANWHILE THE RESIDUAL GULF LOW WILL MOVE INTO THE FL
PANHANDLE...ADVECTING QUITE A BIT OF LOW-LEVEL MOISTURE INTO
SOUTHEAST GA AND CENTRAL SC. RAIN SHOULD OVERSPREAD THE ENTIRE
AREA BY LATE MORNING. WE LEFT ISOLATED THUNDERSTORMS ACROSS FAR
SOUTHEASTERN PORTIONS IN THE AFTERNOON DUE TO A SLUG OF 6C
700-500 MB LAPSE RATES PROGGED TO TREK THROUGH. COLD ADVECTION AND
EVAPORATIONAL COOLING WILL KEEP TEMPERATURES FROM INCREASING VERY
MUCH AFTER DAYBREAK. HIGHS WILL PROBABLY NOT GET ABOVE 60F.
&&
.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
GUIDANCE IS IN GOOD AGREEMENT EJECTING WEAKENING SURFACE LOW
PRESSURE OFF THE GEORGIA COAST SUNDAY NIGHT...THEN TRACKING IT
NORTHEAST ALONG THE CAROLINA COAST INTO MONDAY. AS THIS
OCCURS...OVERRUNNING PRECIPITATION WILL ALLOW A HIGH PRESSURE WEDGE
TO BECOME SOLIDLY ENTRENCHED TO THE LEE OF THE APPALACHIANS AS THE
PARENT HIGH STRENGTHENS OVER NEW ENGLAND. THERE IS SOME UNCERTAINTY
AS TO HOW QUICKLY THE WIDESPREAD RAIN WILL TAPER OFF FROM THE
SOUTHWEST SUNDAY NIGHT...AND SOME CONSIDERATION NEEDS TO BE GIVEN TO
THE NAM WHICH SHOWS A DRY SLOT DEVELOPING OVER THE AREA. AS A
RESULT...THE FORECAST WILL SHOW CATEGORICAL RAIN CHANCES TOWARD THE
SANTEE RIVER DECREASING TO ONLY A CHANCE OF RAIN TOWARD THE ALTAMAHA
RIVER SUNDAY EVENING. RAIN CHANCES LATE SUNDAY NIGHT WILL CONTINUE
TO DIMINISH AS THE DEEPEST MOISTURE SHIFTS NORTH AND EAST OF THE
AREA. AS FOR MONDAY...DEEP MOISTURE WILL BE LACKING BUT PLENTY OF
LOW LEVEL MOISTURE WITHIN THE WEDGE COULD SUPPORT A SLIGHT CHANCE OF
LIGHT RAIN AND/OR DRIZZLE ACROSS THE AREA. TEMPERATURES WILL ALSO BE
SEVERELY IMPACTED BY THE WEDGE...AND GUIDANCE APPEARS MUCH TOO WARM
GIVEN THE EXPECTED SCENARIO...THEREFORE WILL FORECAST HIGHS IN THE
MID 50S WELL INLAND TO AROUND 60 TOWARD THE COAST ON MONDAY.
THE HIGH PRESSURE WEDGE SHOULD PERSIST INTO TUESDAY...BEFORE
GRADUALLY ERODING AS THE PARENT HIGH SHIFTS OFF THE NEW ENGLAND
COAST. ABUNDANT LOW LEVEL MOISTURE WILL KEEP CONSIDERABLE CLOUDINESS
IN PLACE...ALONG WITH THE POTENTIAL FOR AT LEAST PATCHY DRIZZLE.
HIGH TEMPERATURES TUESDAY MAY MODERATE SOME...BUT SHOULD REMAIN
BELOW NORMAL AND WELL BELOW WHAT GUIDANCE SUGGESTS.
WEDNESDAY WILL BE A TRANSITION DAY...WITH DRY CONDITIONS AND NEAR
NORMAL TEMPERATURES EXPECTED. LOW PRESSURE IS EXPECTED TO TRACK
OFFSHORE ALONG THE SOUTHEAST U.S. COAST WEDNESDAY NIGHT INTO
THURSDAY...BUT THERE IS SOME MODEL DISAGREEMENT AS TO HOW FAR
OFFSHORE. THEREFORE...WILL SHOW SOME ISOLATED SHOWERS IN THE
FORECAST FOR WEDNESDAY NIGHT. COOL AND DRY HIGH PRESSURE WILL THEN
BUILD FROM THE WEST LATE IN THE WORK WEEK THROUGH THE FIRST PART OF
THE WEEKEND.
&&
.AVIATION /21Z SATURDAY THROUGH THURSDAY/...
KCHS...CEILING/VSBY RESTRICTIONS NOT LOOKING AS LIKELY TONIGHT DUE
TO THE HIGH PRESSURE SYSTEM TO THE NORTH PUSHING FARTHER TO THE
SOUTH. WE SHOULD PROBABLY SEE SOME LIGHT RAIN INCREASING IN
COVERAGE FROM SW TO NE DURING THE DAY SUNDAY SO WE INCLUDED -RA
STARTING AT 1330Z. CEILING RESTRICTIONS ARE SIGNIFICANTLY MORE
LIKELY BY LATE SUNDAY AFTERNOON INTO SUNDAY EVENING.
KSAV...VFR CONDITIONS SHOULD BEGIN THE PERIOD BUT CEILINGS ARE
EXPECTED TO LOWER LATE TONIGHT AS MOISTURE INCREASES FROM THE
APPROACHING SURFACE LOW. STARTED MVFR CEILINGS AT 08Z. RAIN SHOULD
BEGIN TO SPREAD IN FROM THE SW AFTER 08Z WITH COVERAGE BECOMING
MORE WIDESPREAD BY DAYBREAK. BROUGHT IN PREVAILING MVFR CEILINGS
AND VISIBILITIES BEYOND 13Z.
EXTENDED AVIATION OUTLOOK...MVFR OR LOWER CONDITIONS ARE LIKELY
SUNDAY NIGHT THROUGH TUESDAY. VFR CONDITIONS MAY RETURN ON
WEDNESDAY.
&&
.MARINE...
THE PRESSURE GRADIENT SHOULD INCREASE SUBSTANTIALLY TONIGHT INTO
SUNDAY AS A WEDGE OF HIGH PRESSURE STRENGTHENS FROM THE NORTH
WHILE AN APPROACHING UPPER TROUGH STRENGTHENS A TROUGH AT THE
SURFACE. 20-25 KT WINDS MAY DEVELOP ACROSS THE SC NEARSHORE WATERS
LATE TONIGHT INTO SUNDAY WHILE 6 FT SEAS COULD PUSH INTO OUTER
PORTIONS OF THESE ZONES AS WELL. WE HOISTED A SMALL CRAFT ADVISORY
FOR THE SC NEARSHORE WATERS FROM EDISTO SOUTHWARD TO JOIN THE
EXISTING ADVISORIES FOR THE NORTHERN LEG AND THE OFFSHORE GA LEG.
CONDITIONS WILL BEGIN TO IMPROVE OVER THE WATERS SUNDAY NIGHT DUE
TO A WEAKENING SURFACE PRESSURE GRADIENT AS LOW PRESSURE EJECTS
OFF THE GEORGIA COAST AND TRACKS JUST OFF THE COAST OF SOUTH
CAROLINA. WINDS AND SEAS SHOULD FALL BELOW SMALL CRAFT ADVISORY
CRITERIA OVER THE FAR SOUTHERN SOUTH CAROLINA NEAR SHORE WATERS
SUNDAY EVENING...THEN OVER THE REMAINING SOUTH CAROLINA NEAR SHORE
WATERS AND OUTER GEORGIA WATERS BY LATE SUNDAY NIGHT. A NORTHERLY
FLOW WILL THEN PERSIST THROUGH MID WEEK...WITH SPEEDS 15 KT OR
LESS. AN STRENGTHENING OFFSHORE FLOW IS EXPECTED ON THURSDAY AS
STRONG COLD AIR ADVECTION DEVELOPS OVER THE WATERS.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL MIDNIGHT EST SUNDAY NIGHT FOR
AMZ352.
SMALL CRAFT ADVISORY UNTIL 5 AM EST MONDAY FOR AMZ350-374.
&&
$$
JRL/JAQ
000
FXUS62 KCAE 211951
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
251 PM EST SAT NOV 21 2009
.SYNOPSIS...
A LOW PRESSURE SYSTEM IN THE NORTHWEST GULF OF MEXICO WILL MOVE
SLOWLY NORTHEAST TO THE FLORIDA PANHANDLE TONIGHT...THEN REFORM
ALONG THE CAROLINA COAST SUNDAY NIGHT. HIGH PRESSURE WILL WEDGE
INTO THE CAROLINAS FROM THE NORTH. THIS PATTERN WILL BRING CLOUDS
AND RAIN TO THE AREA THROUGH MONDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
CLOSED UPPER LOW OVER EAST TEXAS WILL DE-AMPLIFY OVERNIGHT AS IT
MOVES NORTHEAST. SURFACE LOW OVER THE NORTHERN GULF OF MEXICO THIS
AFTERNOON WILL SLOWLY MOVE EAST AS HIGH PRESSURE WEDGES INTO THE
CAROLINAS FROM NORTH. SKIES EXPECTED TO BECOME CLOUDY TONIGHT AS
ISENTROPIC LIFT BEGINS. RAIN SPREADING NORTH FROM THE GULF COAST
STATES MAY REACH THE SAVANNAH RIVER AREA BY DAYBREAK SUNDAY. WENT
WITH CONSENSUS LOWS...RANGING FROM THE MID 40S NORTH TO NEAR 50
SOUTH.
&&
.SHORT TERM /SUNDAY THROUGH TUESDAY/...
MODELS FINALLY IN AGREEMENT WITH STRONG ISENTROPIC LIFT OVER THE
AREA SUNDAY AFTERNOON INTO SUNDAY NIGHT. WEAKENING SHORT WAVE
MOVING OUT OF TEXAS TONIGHT WILL CROSS GA INTO THE CAROLINAS
SUNDAY NIGHT. LOW PRESSURE DEVELOPING ON AN INVERTED TROUGH OFF
THE SC COAST. KEPT CATEGORICAL POPS FOR SUNDAY INTO SUNDAY NIGHT.
RAINFALL AMOUNTS RANGING FROM ONE HALF INCH TO AROUND ONE INCH.
THE SURFACE LOW WILL MOVE AWAY FROM THE COAST MONDAY WITH RAIN
CHANCES DECREASING. KEPT CHANCE OF DRIZZLE IN FOR MONDAY NIGHT
INTO TUESDAY.
SINCE WEDGE PATTERN EXPECTED SUNDAY THROUGH TUESDAY...SHOULD SEE
PLENTY OF CLOUDS. KEPT DAYTIME TEMPERATURES BELOW GUIDANCE. HIGHS
IN THE LOW TO MID 50S (WHICH MAY BE ON THE HIGH SIDE). LITTLE DIURNAL
CHANGE IN TEMPERATURES EXPECTED. LOWS IN THE MID TO UPPER 40S.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
MEDIUM RANGE MODELS DEPICT A SERIES OF MID/UPPER LEVEL LOWS MOVING
ACROSS THE UPPER MIDWEST TO THE EASTERN GREAT LAKES AND
SOUTHEASTERN CANADA TUESDAY NIGHT INTO SATURDAY. ALL IN ALL,
SLIGHT UPPER RIDGING OVER THE SOUTHEAST PART OF THE COUNTRY
TUESDAY IS REPLACED BY A LARGE UPPER TROUGH OVER THE EASTERN
UNITED STATES WEDNESDAY THROUGH FRIDAY. UPPER TROUGH FINALLY MOVES
OFF THE EAST COAST SATURDAY. SURFACE HIGH PRESSURE CENTERED OVER
SOUTHEASTERN CANADA TUESDAY NIGHT RIDGING INTO THE AREA FROM THE
NORTH. SURFACE LOW PRESSURE CROSSING THE GREAT LAKES REGION ON
THANKSGIVING DAY WILL DRAG A COLD FRONT ACROSS THE AREA. MOISTURE
APPEARS LIMITED SINCE THE BEST ISENTROPIC LIFT REMAINS SOUTH AND
EAST OF THE FORECAST AREA. ANY CHANCE FOR RAIN (WHICH IS SLIGHT)
LOOKS LIKE WEDNESDAY INTO THURSDAY MORNING. COOL HIGH PRESSURE
BUILDS IN FOR FRIDAY AND SATURDAY. WILL KEEP THE EXTENDED FORECAST
DRY. SEASONABLY MILD MAX TEMPERATURES WEDNESDAY AND THURSDAY COOL
A FEW DEGREES BELOW NORMAL FOR FRIDAY AND SATURDAY. NIGHTTIME LOWS
IN THE 40S MID-WEEK COOLING TO THE MID AND UPPER 30S BY LATE NEXT
WEEK.
&&
.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
HIGH PRESSURE TO OUR NORTH WILL CONTINUE TO KEEP VFR CONDITIONS
OVER CENTRAL SOUTH CAROLINA AND THE CENTRAL SAVANNAH RIVER AREA
THROUGH MUCH OF THE TAF FORECAST PERIOD.
LOW PRESSURE CURRENTLY CENTERED SOUTHWEST OF NEW ORLEANS IS FORECAST
TO MOVE NORTHEAST OVER THE NEXT 24 HOURS TO THE NORTHWEST FLORIDA
PANHANDLE BY SUNDAY AFTERNOON. MODEL GUIDANCE HAS BEEN SLOWING THE
PROGRESS AND THE INTENSITY OF THE SYSTEM OVER THE PAST SEVERAL MODEL
RUNS. LOOKS LIKE MVFR TO IFR FLYING CONDITIONS WILL BE DELAYED TO
LATER IN THE FORECAST PERIOD WITH THE GREATEST THREAT BEING LATE
SUNDAY AND SUNDAY NIGHT. WITH THIS IN MIND...SLOWED THE LOWERING
OF THE CEILING AND VISIBILITY WITH MVFR CONDITIONS OVERSPREADING
THE AREA LATE IN THE FORECAST PERIOD.
EXTENDED AVIATION OUTLOOK...WIDESPREAD MVFR OR IFR CONDITIONS WILL
LIKELY OCCUR LATE SUNDAY...SUNDAY NIGHT AND MONDAY. LOW PRESSURE
WILL MOVE ACROSS SOUTHERN GEORGIA AND THEN NORTHEAST UP THE SOUTH
CAROLINA COAST DURING THAT TIME PERIOD SPREADING LOW CEILINGS AND
VISIBILITY ACROSS THE AREA.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
SYNOPSIS...LM
NEAR TERM...LM
SHORT TERM...LM
LONG TERM...LM
AVIATION...GL
000
FXUS62 KGSP 211901
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
201 PM EST SAT NOV 21 2009
.SYNOPSIS...
HIGH PRESSURE OVER THE REGION WILL SHIFT NORTH OVER THE WEEKEND.
THIS WILL ALLOW A LOW PRESSURE SYSTEM TO MOVE EAST ALONG THE GULF
COAST THEN NORTH ALONG THE CAROLINA COAST SUNDAY THROUGH MONDAY.
THE LOW IS EXPECTED TO REACH THE NEW ENGLAND COAST BY TUESDAY AS
WEAK HIGH PRESSURE REMAINS OVER THE SOUTHEAST STATES. ANOTHER COLD
FRONT OR COASTAL LOW COULD MOVE INTO THE AREA BY THE MIDDLE OF NEXT
WEEK.
&&
.NEAR TERM /THROUGH SUNDAY/...
CONFLUENT FLOW OFF THE NEW ENGLAND COAST WILL GRADUALLY STRENGTHEN
SFC HIGH PRESSURE OVER THE MID ATLANTIC STATES THROUGH SUNDAY. THE
MORNING UPPER AIR SHOWED VERY DRY AIR DOWN ALONG THE GULF COAST. FOR
EXAMPLE...THE TALLAHASSEE RAOB HAD A 40 DEGREE DEWPOINT DEPRESSION
AT 850 MB. WITH THIS MUCH DRY AIR TO THE SOUTH...AND WITH A
DEVELOPING CLASSICAL COLD AIR DAMMING EVENT...IT/S NOT SURPRISING
THAT THE MODELS HAVE BEEN DELAYING THE ONSET OF PCPN OVER THE PAST
SEVERAL RUNS. AT LEAST THE GFS HAS TONED DOWN THE POT VORT MAXES AND
HEAVY PCPN THAT IT HAD BEEN DRIVING ACROSS THE HEART OF THE WEDGE
RIDGE. THIS SEEMS MORE REALISTIC AS QPF SHOULD BE FAIRLY LIGHT
WITH THE LLVL DRY AIR AND THE WEAKENING SRN STREAM SYSTEM. THE BEST
CHANCES FOR HEAVY RAIN WILL BE ALONG THE COASTAL FRONT...WELL TO OUR
SOUTH.
OVERALL...THE SREF SEEMS TO HAVE DONE THE BEST JOB OF HANDLING THE
EVOLUTION OF THE GULF COAST LOW AND PCPN DISTRIBUTION SO FAR. I/VE
FOLLOWED IT FAIRLY CLOSELY FOR THE TIMING OF PCPN. THIS MEANS A DRY
FORECAST TONIGHT. PCPN SHOULD OVERSPREAD THE REGION FROM THE
SOUTHWEST ON SUNDAY...THOUGH I DON/T SEE ANYTHING FALLING NORTH OF
GREENVILLE UNTIL THE AFTERNOON HOURS. I RAISED MAX TEMPS A COUPLE
CATEGORIES OVER THE NE ZONES WHERE THINNER CLOUD COVER EARLY IN THE
DAY WILL RESULT IN A LITTLE MORE WARMING THAN ORIGINALLY EXPECTED. I
FOLLOWED A MET/MAV BLEND AND WE MATCH UP WELL WITH THE NEIGHBORS.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/...
AS OF 130 PM SATURDAY...NOT THAT THERE IS A GREAT DEAL OF CONFIDENCE
WITH REGARDS TO THE SPECIFICS OF THE SUNDAY NIGHT FCST...BUT LIKELY
SOME DEGREE OF DEEP RH AND ESE FLOW ABOVE LINGERING WEDGE WILL REMAIN
ALL NIGHT. SENSIBLE WX IS STILL EXPECTED TO BE DAMP WITH RAINY AND
DRIZZLY PERIODS...ALTHOUGH PCPN TOTALS WILL BE MODERATE AT WORST.
CONFIDENCE INCREASING THAT DAMMING REGIME WILL REMAIN THRU
MONDAY...ALTHOUGH FORCING FOR ADDITIONAL PCPN WILL WANE...EVENTUALLY
JUST BEING FORCED BY SOME DEGREE OF WAA/EASTERLY FLOW JUST ABV SFC.
EVEN THE MILDER 12 UTC MET NUMBERS...WHICH WILL PROBABLY BE TOO WARM
ANYWAY...SUPPORT NOTABLE LOWERING OF GOING MAX TEMPS. GIVEN THE
WEAKENING OF THE LLVL FLOW MONDAY NIGHT AND RESIDUAL WEAK SFC
RIDGING...THERE SEEMS TO BE LITTLE HOPE OF SCOURING...SO WILL PLAN
ON LEAVING OVC CONDS WITH SPOTTY AREAS OF LIGHT RAIN/DRIZZLE...
ESPECIALLY ALONG AND EAST OF THE ESCARPMENT WHERE WEAK LLVL
EASTERLY FLOW WILL CONTINUE TO LIFT SHALLOW MOISTURE.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 145 PM SATURDAY...NOT MUCH AGREEMENT IS SEEN IN THE OP MODELS
WITH RESPECT TO AMOUNT OF DEEPENING OF THE MID WEEK CUT OFF LOW AND
THE LEVEL OF MOISTURE AVAILABLE FOR THE OCCLUDED FRONT TO WORK WITH
ONCE IT REACHES THE CWFA WED MORNING. EVEN LESS AGREEMENT IS SEEN
BETWEEN THE GFS AND THE ECMWF ON THU/FRI WITH THE POLAR VORTEX
REINFORCING THE GLAKES LOW AND THE EVENTUAL TRACK AND SPEED OF THE
LARGE SCALE PATTERN. THE GFS H5 ENS MEMBERS SHOW THE HIGHEST SPREAD
EARLY FRI MORNING WITH ABOUT 8 DM OF UNCERTAINTY ASSOCIATED WITH
THE HEIGHT FIELD...LENDING LOW CONFIDENCE TOWARD THE SETUP FOR A
POSSIBLE MINIMAL NW FLOW EVENT.
NOT MANY CHANGES HAVE BEN MADE TO THE GOING FORECAST WITH LITTLE
CONFIDENCE HAD BOTH IN THE OP MODELS AND HPC GUIDANCE. SOME DECENT
AGREEMENT IS SEEN TUE WITH THE SLOWER BREAKDOWN OF THE SFC WEDGE.
MODEL SOUNDINGS INDICATE RATHER THICK STRATUS HANGING ON THROUGHOUT
THE DAY AND VERY LOW WINDS IN THE BL. SO...MAX TEMP GUIDANCE HAS
BEEN CUT BACK A CAT OR SO OUTSIDE THE MTNS TO ACCOUNT FOR THIS
POSSIBLE SCENARIO. POPS STILL SEEM SUSPECT WITH LITTLE IN THE WAY OF
ORGANIZED FLOW INTERACTING OVER THE WEDGE...SO THE LINGERING SLIGHT
CHANCES WERE CHANGED LITTLE.
THE GFS IS MORE AGGRESSIVE IN BRINGING A MOIST OCCLUDED FRONT TO THE
MTNS BY 12Z WED THAN THE ECMWF. THE EC DOES EVENTUALLY BRING THE
FRONT TO THE AREA LATE IN THE DAY...BUT BOTH MODELS CUT OFF THE GOM
MOISTURE FLUX WITH LLVL RIDGING FROM THE WEST. WITH THE MAIN LARGE
SCALE FORCING SHIFTED NORTH...WILL COUNT ON VERY LITTLE IMPACT AS
FAR A PRECIP COVERAGE GOES. FOR NOW...SLIGHT CHANCES WILL
REMAIN...BUT THIS COULD BE INCREASED ONCE BETTER DATA IS GLEANED ON
THIS SYSTEM.
THE NEXT SYSTEM TO THINK ABOUT WILL BE THU/FRI...AS THE GFS INSISTS
ON A MOIST NW FLOW EVENT...YET THE EC REMAINS DRY AND LOW KEY ON THE
KINEMATIC SETUP. THE GFS AS MENTIONED EARLIER IS BRINGING IN A MUCH
STRONGER REINFORCING POLAR VORTEX INTO THE GLAKES LOW...ABOUT TWICE
AS STRONG PVU/WISE THAN THE ECMWF. THIS SEEMS A LITTLE TOO STRONG
FOR THIS TIME OF YEAR...AND FOR NOW WILL SIDE WITH THE MORE
CONSERVATIVE ECMWF ON THIS ONE. THUS...MINIMAL POPS AND AN ALL RAIN
P/TYPE ARE ADVERTISED FOR THAT PERIOD.
OTHER THAN THE LOWER THAN NORMAL POPS EXPECTED TUE....MAX TEMPS
SHOULD REBOUND RATHER NICELY WED THROUGH FRI. INCREASED INSOLATION
AND A WAA FLOW WILL ENABLE MAXES AT OR PERHAPS A COUPLE DEGREES
ABOVE NORMAL. THE NC MTNS WILL BE TRICKERY FRI...AS IT/S PROBABLE
THAT CAA ASSOCIATED WITH THE PASSING VORTEX TO THE NORTH LOWERS
TEMPS THROUGHOUT THE DAY. YET FOR NOW...WILL ONLY GO A COUPLE
DEGREES BELOW NORMAL WITH SO MUCH UNCERTAINTY AND POOR CONTINUITY
DISPLAYED BY THE GUIDANCE.
&&
.AVIATION /19Z SATURDAY THROUGH THURSDAY/...
AT KCLT AND ELSEWHERE...THE LATEST COMPUTER MODELS HAVE SLOWED DOWN
THE PROGRESSION OF LOW CLOUDS AND PRECIPITATION ASSOCIATED WITH THE
LOW COMING OUT OF THE GULF. WHILE THE CIGS WILL GRADUALLY FALL
DURING THE FORECAST PERIOD...ONLY VFR CIGS ARE EXPECTED THROUGH 18
UTC SUN. WINDS WILL BE LIGHT OUT OF THE E TO ENE THIS AFTN...BACKING
A LITTLE MORE TO THE NORTH TONIGHT AND SUN MORNING. THE EXCEPTION IS
KAVL WHERE THE WINDS WILL BE LIGHT OUT OF THE SE TODAY...NEARLY CALM
TONIGHT...AND SE AGAIN ON SUN.
OUTLOOK...CLOUD CEILINGS WILL LOWER MORE QUICKLY SUNDAY AFTERNOON AS
RAIN SPREADS ACROSS THE AREA. MVFR CONDITIONS EXPECTED MOST OF THE
AFTN. IFR CIGS AND MVFR FOG ARE STILL EXPECTED TO DEVELOP SUNDAY
NIGHT...LASTING INTO TUESDAY. CONDITIONS MAY NOT IMPROVE MUCH ON
WEDNESDAY AS A WEDGE OF COOL MOIST AIR PERSISTS OVER THE REGION.
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...PAT
NEAR TERM...MCAVOY
SHORT TERM...CSH
LONG TERM...SBK
AVIATION...MCAVOY
000
FXUS62 KCHS 211751
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
1251 PM EST SAT NOV 21 2009
.SYNOPSIS...
HIGH PRES WILL REMAIN N OF THE REGION THROUGH TONIGHT. AN AREA OF LOW
PRES WILL TRACK ALONG THE GULF COAST STATES AND INTO THE ATLC OFF
THE SOUTHEAST GEORGIA COAST SUNDAY AND SUNDAY NIGHT. THIS SYSTEM
WILL THEN MOVE NE ALONG THE EASTERN SEABOARD...AS HIGH PRES HOLDS
IN PLACE INLAND. HIGH PRES WILL SLOWLY BECOME MORE DOMINANT FROM
MID-LATE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
MID AND HIGH CLOUDS WILL CONTINUE TO INCREASE FROM THE SW TODAY
AHEAD OF AN APPROACHING UPPER TROUGH. MEANWHILE THE LOW STRATUS
FROM THIS MORNING SHOULD SLOWLY BURN OFF...BUT LOW-LEVEL CLOUDS
WILL PROBABLY INCREASE LATE IN THE DAY AS ISENTROPIC LIFT BEGINS.
THERE WILL BE LITTLE IN THE WAY OF FORCING FOR PRECIP EXCEPT JUST
OFF THE CHARLESTON COUNTY COAST WHERE AN ISOLATED SHOWER COULD
DEVELOP IN THE COASTAL TROUGH. ONGOING FORECAST OF HIGHS IN THE
MIDDLE TO UPPER 60S LOOKED GOOD BASED ON LATEST TRENDS SO WE MADE
ONLY MINOR TWEAKS TO TODAY/S GRAPHICS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SUNDAY/...
THE VIGOROUS SOUTHERN STREAM SYSTEM WILL LIFT FROM SE TEXAS TODAY
INTO THE LOWER MISSISSIPPI VALLEY REGION BY 12Z ON SUNDAY. DYNAMIC
INFLUENCES WILL GUIDE SIGNIFICANT RAINS INTO WESTERN AND N GEORGIA
BY DAWN WITH ISENTROPIC LIFT AND DEEP MOISTURE GRADUALLY INCREASING
OVERNIGHT OVER OUR FORECAST AREA. THE GFS IS NOW A FASTER OUTLIER
IN SPREADING RAINS THROUGH OUR ENTIRE FORECAST AREA AFTER MIDNIGHT
TONIGHT. THE BAROCLINIC ZONE WILL LIKELY PERSIST OFF THE COAST AND
DEEP LAYERED CONVERGENCE AND UPPER FORCING WILL LIKELY INCITE
RAINFALL DEVELOPMENT SW OF THE SAVANNAH RIVER SHORTLY BEFORE
DAYBREAK ON SUNDAY. COASTAL SOUTH CAROLINA APPEARS TO BE BETWEEN
THE APPROACHING DYNAMICS AND THE OFFSHORE FRONTAL ZONE AND WE
TRIMMED POPS BACK TO A LOW END CHANCE LATE TONIGHT. CLOUDS AND
A LIGHT/STEADY NE FLOW SHOULD KEEP TEMPERATURES IN THE LOWER TO
MID 50S COASTAL AREAS WITH SOME UPPER 40S CLOSER TO THE CSRA AND
MIDLANDS WHERE THE SURFACE WEDGE WILL BE ENTRENCHED.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
MEDIUM RANGE GUIDANCE IS IN GOOD AGREEMENT THROUGH EARLY NEXT
WEEK...WITH SOLUTIONS THEN DIVERGING DURING THE LAST SEVERAL DAYS OF
THE EXTENDED FORECAST PERIOD. AS A RESULT...CONFIDENCE IS NEAR
NORMAL THROUGH MONDAY...THEN DROPS BELOW NORMAL TUESDAY THROUGH
FRIDAY.
GUIDANCE HAS COME INTO GOOD AGREEMENT BRINGING A WEAKENING WAVE OF
LOW PRESSURE ACROSS THE NORTHERN GULF COAST STATES SUNDAY AND
TRACKING ACROSS THE GEORGIA/FLORIDA BORDER SUNDAY NIGHT. AS THIS LOW
PASSES BY TO THE SOUTH OF THE FORECAST AREA...A WEDGE OF HIGH
PRESSURE WILL HOLD IN PLACE ACROSS MUCH OF THE EASTERN THIRD OF THE
COUNTRY. THE AREA OF LOW PRESSURE WILL THEN TRACK NORTHEASTWARD OFF
THE EASTERN SEA BOARD AND INTO THE SOUTHERN NEW ENGLAND MONDAY
THROUGH TUESDAY...HELPING TO RE-ENFORCE THE EXISTING HIGH PRESSURE
WEDGE ACROSS THE FORECAST AREA.
MODEL SOLUTIONS THEN REMAIN SPLIT ON DEGREE OF PHASING BETWEEN THE
NORTHERN AND SOUTHERN STREAM WEDNESDAY THROUGH THURSDAY...WITH THE
GFS AND CANADIAN SOLUTIONS SHOWING LITTLE PHASING. AS A
RESULT...THESE MODELS KEEP THE FORECAST AREA UNDER THE INFLUENCE OF
HIGH PRESSURE WITH LITTLE CHANCE FOR RAIN. ON THE OTHER-HAND...THE
ECMWF AND UKMET MODELS DEPICT THE TWO STREAMS PHASING...WHICH
RESULTS IN A WAVE OF LOW PRESSURE TRACKING THROUGH THE SOUTHEAST
STATES ALONG WITH RAIN CHANCES WEDNESDAY THROUGH THURSDAY. GUIDANCE
THEN COMES INTO AGREEMENT BUILDING HIGH PRESSURE INTO THE AREA
THURSDAY NIGHT AND FRIDAY.
AS FOR FORECAST DETAILS...WILL CARRY LIKELY/CATEGORICAL POPS SUNDAY
AND SUNDAY NIGHT AS GOOD FORCING FOR ASCENT ALONG WITH DEEP MOISTURE
AND ISENTROPIC UPGLIDE OVERSPREAD THE FORECAST AREA. MODEL SOLUTIONS
DEPICT SOME DECENT MID-LEVEL LAPSE RATES ON THE ORDER OF 6.5 C/KM
MOVING THROUGH SUNDAY AFTERNOON THROUGH SUNDAY EVENING. ALTHOUGH A
STRONG SURFACE HIGH PRESSURE WEDGE WILL BE IN PLACE...GIVEN THE
DEGREE OF FORCING MOVING OVERHEAD...CAN/T RULE OUT ELEVATED
CONVECTION...SO WILL CARRY THUNDER MENTION IN THE FORECAST AS WELL.
AS SURFACE HIGH PRESSURE WEDGE IS RE-ENFORCED MONDAY THROUGH TUESDAY
AS THE SURFACE AREA OF LOW PRESSURE LIFTS NORTHWARD TOWARD NEW
ENGLAND...NOT ANTICIPATING MUCH IF ANY CLEARING ACROSS THE FORECAST
AREA. MODEL TIME HEIGHT RELATIVE HUMIDITY CROSS SECTIONS INDICATE
THAT THE 1000-850 MB LAYER WILL REMAIN NEARLY SATURATED THROUGH THIS
PERIOD...SO WILL CARRY SLIGHT CHANCE/LOW CHANCE POPS AND MENTION OF
DRIZZLE ACROSS THE FORECAST AREA. HAVE SIGNIFICANTLY UNDERCUT MOS
GUIDANCE MAX TEMPERATURES AS WELL...AS LIGHT WIND FIELDS COMBINED
WITH THE LOW SUN ANGLE SHOULD LEAD TO PRIMARILY OVERCAST CONDITIONS
AND SMALL DIURNAL TEMPERATURE SWINGS.
FORECAST CONFIDENCE GOES DOWNHILL QUICKLY WEDNESDAY AND THURSDAY
WITH GUIDANCE SOLUTIONS SPLIT ON EVENTUAL PATTERN EVOLUTION. FOR NOW
WILL STICK WITH A SOLUTION CLOSE TO THE GFS AND CANADIAN SOLUTIONS
WHICH MAINTAINS GOOD FORECAST CONTINUITY AND AWAIT BETTER MODEL
AGREEMENT BEFORE MAKING ANY SWEEPING CHANGES. THIS RESULTS...IN A
RAIN FREE FORECAST WEDNESDAY THROUGH FRIDAY.
&&
.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
KCHS...CEILING/VSBY RESTRICTIONS NOT LOOKING AS LIKELY TONIGHT DUE
TO THE HIGH PRESSURE SYSTEM TO THE NORTH PUSHING FARTHER TO THE
SOUTH. WE SHOULD PROBABLY SEE SOME LIGHT RAIN INCREASING IN
COVERAGE FROM SW TO NE DURING THE DAY SUNDAY SO WE INCLUDED -RA
STARTING AT 1330Z. CEILING RESTRICTIONS ARE SIGNIFICANTLY MORE
LIKELY BY LATE SUNDAY AFTERNOON INTO SUNDAY EVENING.
KSAV...VFR CONDITIONS SHOULD BEGIN THE PERIOD BUT CEILINGS ARE
EXPECTED TO LOWER LATE TONIGHT AS MOISTURE INCREASES FROM THE
APPROACHING SURFACE LOW. STARTED MVFR CEILINGS AT 08Z. RAIN SHOULD
BEGIN TO SPREAD IN FROM THE SW AFTER 08Z WITH COVERAGE BECOMING
MORE WIDESPREAD BY DAYBREAK. BROUGHT IN PREVAILING MVFR CEILINGS
AND VISIBILITIES BEYOND 13Z.
EXTENDED AVIATION OUTLOOK...MVFR OR LOWER CIGS AND VSBYS LIKELY
SUNDAY NIGHT THROUGH TUE. VFR CONDITIONS MAY RETURN ON WED.
&&
.MARINE...
THE PRES GRADIENT WAS PINCHING PRE-DAWN FROM AROUND BUOY 41004 UP
TO THE BUOY 41013. NNE FLOW AVERAGING 10 TO 15 KT OVER OUR WATERS
THIS MORNING...EXCEPT COASTWARD FROM GRAYS REEF WHERE SPEEDS WERE
FAIRLY LIGHT IN A WEAKER GRADIENT. SEAS WERE ELEVATED BEYOND 40
NM OFF THE COAST ACCORDING TO STEADY WAVEWATCH OUTPUT AND FETCH
LENGTH AND PERSISTENCE PROGS. WE WILL CONTINUE WITH MARGINAL
SMALL CRAFT ADVISORY CONDITIONS...MAINLY FOR SEAS OVER OUR OUTER
GEORGIA WATERS. THE COASTAL CAROLINAS PRES GRADIENT WILL TIGHTEN
TONIGHT AND WITH STEADY NE FLOW...IT APPEARS SEAS WILL BUILD INTO
SCA RANGE OFF AT LEAST THE CHARLESTON COUNTY COAST OVERNIGHT. THE
MODELS COULD BE UNDERDONE WITH THE PINCHING AND FORECAST CONDITIONS
MAY TURN OUT SOMEWHAT OPTIMISTIC. OUTER GEORGIA WATERS WILL REMAIN
IN SCA CONDITIONS TONIGHT.
AN AREA OF LOW PRESSURE WILL TRACK EASTWARD ALONG THE NORTHERN GULF
COAST AND GEORGIA/FLORIDA BORDER REGION SUNDAY AND SUNDAY
NIGHT...THEN NORTHEASTWARD ALONG THE EASTERN SEABOARD AND INTO
SOUTHERN NEW ENGLAND MONDAY THROUGH TUESDAY. HIGH PRESSURE WILL THEN
BUILD IN FROM THE WEST ON WEDNESDAY.
EXPECT A FAIRLY STRONG PINCHED GRADIENT ACROSS THE WATERS SUNDAY AND
SUNDAY NIGHT...WITH SMALL CRAFT CONDITIONS CONTINUING ACROSS
PORTIONS OF THE WATERS. AS LOW PRESSURE PULLS AWAY FROM THE REGION
MONDAY...EXPECT IMPROVING CONDITIONS WITH WINDS AND SEAS REMAINING
BELOW SMALL CRAFT THRESHOLDS THROUGH WEDNESDAY.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 5 AM EST MONDAY FOR AMZ374.
SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 5 AM EST
MONDAY FOR AMZ350.
&&
$$
JRL
000
FXUS62 KGSP 211747
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1247 PM EST SAT NOV 21 2009
.SYNOPSIS...
HIGH PRESSURE OVER THE REGION WILL SHIFT NORTH OVER THE WEEKEND.
THIS WILL ALLOW A LOW PRESSURE SYSTEM TO MOVE EAST ALONG THE GULF
COAST THEN NORTH ALONG THE CAROLINA COAST SUNDAY THROUGH MONDAY.
THE LOW IS EXPECTED TO REACH THE NEW ENGLAND COAST BY TUESDAY AS
WEAK HIGH PRESSURE REMAINS OVER THE SOUTHEAST STATES. ANOTHER COLD
FRONT OR COASTAL LOW COULD MOVE INTO THE AREA BY THE MIDDLE OF NEXT
WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
CURRENT FORECAST IS IN GOOD SHAPE. I INCREASED THE OPAQUE CLOUD
COVER TODAY BASED ON CURRENT TRENDS...BUT THAT/S ALL I NEEDED TO
TWEAK. PREVIOUS DISCUSSION FOLLOWS...
CURRENT IR SATELLITE IMAGERY INDICATES THAT CIRRUS SHIELD CONTINUES
TO STREAM IN FROM THE SOUTHWEST...AND IS EXPECTED TO CONTINUE
THROUGHOUT THE NEAR TERM PERIOD. MAIN FORECAST PROBLEM THROUGH
TONIGHT CENTERS AROUND THE DEVELOPING WEDGE AND CYCLOGENESIS OVER
THE NORTHERN GULF. CURRENT SUITE OF MODEL RUNS FAVOR MUCH SLOWER
TIMING OF DEEP LAYER MOISTURE SPREADING OVER TOP OF THE COLD DOME.
IN FACT...EVEN THE FASTER GFS SOLUTION SUPPORTS A DRY FORECAST
THROUGH 06Z. THEREFORE...I HAVE TRIMMED POPS SIGNIFICANTLY FEATURING
ONLY LOW END CHANCE POPS ACROSS THE SOUTHWESTERN THIRD OF THE
FA...SIMILAR TO THE SREF. AS IT STANDS NOW ONLY THE GFS BRINGS MUCH
IN THE WAY OF ISENTROPIC LIFT INTO THE AREA BY 12Z SO AS IT STANDS
EVEN THIS POP COULD BE A BIT OVERDONE. THE SURFACE HIGH SLIDES INTO
A MORE FAVORABLE WEDGE POSITION THROUGH THE AFTERNOON AND SHOULD BE
WELL IN PLACE BY MID TO LATE MORNING.
I HAVE BLENDED HIGH TEMPS DOWNWARD A BIT TODAY...MORE TOWARD MOS
GUIDANCE. WITH CONSIDERABLE HIGH CLOUDS IN PLACE...SHOULD HELP LIMIT
MAX TEMPS. EXPECT LOW 60S OUTSIDE THE MOUNTAINS...AND UPPER 50S IN
THE MOUNTAIN VALLEYS. LOWS WILL DIP INTO THE LOW TO MID 40S.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 230 AM EST SATURDAY...A SOUTHERN STREAM UPPER LOW WILL MOVE
FROM THE GULF STATES TO THE APPALACHIANS ON SUNDAY AND SUNDAY NIGHT
WHILE WEAKENING. ON MONDAY AND MONDAY NIGHT AND UPPER RIDGE
AMPLIFIES OVER THE SOUTHEAST. THE GFS CONTINUES TO BE FASTER TO
SPREAD MOISTURE AND ISENTROPIC UPGLIDE NORTHEAST ACROSS THE AREA ON
SUNDAY...AND CLOUD COVER AND POPS HAVE BEEN REDUCED TO FAVOR THE
SLOWER NAM/ECMWF SOLUTIONS. POPS HAVE BEEN INCREASED SUNDAY NIGHT
AND MONDAY TO INDICATE A SLOWER EVOLUTION OF COLD AIR DAMMING...
AND A MORE PROLONGED EVENT...WITH LESS OF A DECREASE OF CLOUDS ON
MONDAY NIGHT. SMALL POPS WILL EVEN BE CARRIED ALONG THE BLUE RIDGE
ESCARPMENT MONDAY NIGHT WHERE THE ECMWF INDICATED SOME LINGERING
MOIST UPSLOPE FLOW. MAXIMUM TEMPERATURES HAVE BEEN RAISED A BIT ON
SUNDAY...AND LOWERED ON MONDAY...TO INDICATE THE DELAYED ONSET OF
COLD AIR DAMMING...WITH MINIMUM RAISED SUNDAY NIGHT AND MONDAY
NIGHT. NONE OF THE MODELS HAS NEAR THE AMOUNT OF UPGLIDE OR UPSLOPE
FLOW...SO ONLY MODEST RAINFALL AMOUNTS WIL BE CARRIED...WITH SOME
TERRAIN ENHANCEMENT NEAR THE SOUTH AND SOUTHEAST FACING BLUE RIDGE
ESCARPMENT OF GA AND SC.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 315 AM SATURDAY...HPC CONTINUES TO PREFER THE ECMWF FOR THE
MEDIUM RANGE. THERE ARE DIFFERENCES BETWEEN IT AND THE GFS AND
GEM...WHICH HAVE SIMILAR SOLUTIONS. HOWEVER...THE 00Z ECMWF HAS
TRENDED TOWARD THE GFS AND GEM SOLUTIONS. GIVEN THESE DIFFERENCES
THE EXTENDED FCST REMAINS LOW CONFIDENCE.
THE MODELS AGREE THAT A CLOSED UPPER LOW OVER THE OVER THE PLAINS
MOVES EAST AS A STRONG SHORT WAVE DIVES IN BEHIND THE LOW CREATING
AN EASTERN US TROF. THIS WAVE THEN MERGES WITH OR TAKES THE PLACE OF
THE PREVIOUS LOW AS IT THEN MOVES OFF THE COAST. AT THE SFC...CAD
BEGINS TO ERODE...BUT THERE COULD BE SOME LINGERING PATCHY RAIN TUE
AND TUE NITE. THEN ANOTHER OCCLUDED FNT APPROACHES THE AREA WED AS A
GULF COAST LOW DEVELOPS. THE GFS/GEM KEEP THE FCST DRY AS THE DYING
OCCLUDED FNT HAS LITTLE MOISTURE AND THE COASTAL LOW REMAINS VERY
FAR SOUTH. THE ECMWF HAS MUCH MORE MOISTURE OVER THE AREA AS THE LOW
RIDES ALONG THE COAST. THE ECMWF THEN DRIES THINGS OUT THU AS THE
LOW MOVES UP THE EAST COAST AND AWAY FROM THE AREA. BOTH MDLS SHOW
SOME NW FLOW MOISTURE THU AND FRI. HOWEVER...THE GFS IS MUCH WETTER
AND COLDER SUGGESTING A P-TYPE OF SNOW. GIVEN ALL THIS
UNCERTAINTY...WILL KEEP POPS LIMITED TO SLIGHT CHC. TEMPS START OUT
ABOVE NORMAL THEN COOL BELOW NORMAL. KEPT MTN TEMPS ABOVE FREEZING
DURING THE PERIODS WITH PRECIPITATION...FOR A RAIN P-TYPE.
&&
.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
AT KCLT AND ELSEWHERE...THE LATEST COMPUTER MODELS HAVE SLOWED DOWN
THE PROGRESSION OF LOW CLOUDS AND PRECIPITATION ASSOCIATED WITH THE
LOW COMING OUT OF THE GULF. WHILE THE CIGS WILL GRADUALLY FALL
DURING THE FORECAST PERIOD...ONLY VFR CIGS ARE EXPECTED THROUGH 18
UTC SUN. WINDS WILL BE LIGHT OUT OF THE E TO ENE THIS AFTN...BACKING
A LITTLE MORE TO THE NORTH TONIGHT AND SUN MORNING. THE EXCEPTION IS
KAVL WHERE THE WINDS WILL BE LIGHT OUT OF THE SE TODAY...NEARLY CALM
TONIGHT...AND SE AGAIN ON SUN.
OUTLOOK...CLOUD CEILINGS WILL LOWER MORE QUICKLY SUNDAY AFTERNOON AS
RAIN SPREADS ACROSS THE AREA. MVFR CONDITIONS EXPECTED MOST OF THE
AFTN. IFR CIGS AND MVFR FOG ARE STILL EXPECTED TO DEVELOP SUNDAY
NIGHT...LASTING INTO TUESDAY. CONDITIONS MAY NOT IMPROVE MUCH ON
WEDNESDAY AS A WEDGE OF COOL MOIST AIR PERSISTS OVER THE REGION.
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...RWH
NEAR TERM...BSH/MCAVOY
SHORT TERM...JAT
LONG TERM...RWH
AVIATION...MCAVOY
000
FXUS62 KCAE 211728
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
1228 PM EST SAT NOV 21 2009
.SYNOPSIS...
HIGH PRESSURE OVER THE REGION TODAY WILL WEAKEN TONIGHT. LOW
PRESSURE WILL MOVE EAST ALONG THE GULF COAST TONIGHT AND SPREAD
RAIN TO THE AREA SUNDAY AND SUNDAY NIGHT. THE LOW WILL BEGIN TO
MOVE AWAY MONDAY AND THE CHANCES OF RAIN WILL DECREASE. HIGH
PRESSURE WILL BUILD IN MONDAY NIGHT AND TUESDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
HIGH PRESSURE WILL MOVE EAST AND CLOUDS WILL INCREASE FROM THE
SOUTH AS A LOW PRESSURE AREA MOVES TOWARD THE REGION. CONDITIONS
WILL REMAIN DRY TODAY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY/...
AN APPROACHING LOW PRESSURE AREA WILL SPREAD CLOUDS AND RAIN OVER
THE REGION LATE TONIGHT AND SUNDAY. THE RAIN WILL CONTINUE SUNDAY
NIGHT. THE LOW WILL MOVE OFFSHORE AND AWAY MONDAY DECREASE THE
CHANCES OF RAIN. THE RAIN SHOULD BE GONE LATE IN THE DAY MONDAY.
COOL TEMPERATURES ARE EXPECTED WITH SUNDAY HIGHS IN THE LOWER 50S
AND MONDAY HIGHS IN THE LOWER 60S. QPF AMOUNTS SHOULD BE AROUND
ONE INCH.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
IN GOOD AGREEMENT WITH LONG RANGE MODELS BRINGING LONG WAVE TROUGH
PATTERN BACK TO THE EAST. THIS SHOULD INCREASE NORTHWEST WIND FLOW
AT THE SURFACE AS A COUPLE OF DRY COLD FRONTS SWEEP THROUGH THE
REGION. THIS WILL ALSO GIVE THE AREA COOLER TEMPERATURES. HIGHS IN
THE MID 60S TUESDAY AND WEDNESDAY COOL TO NEAR 60 THANKSGIVING
DAY AND BLACK FRIDAY. OVERNIGHT LOWS IN THE 40S START OF PERIOD
LOWER TO THE 30S BY FRIDAY MORNING.
&&
.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
HIGH PRESSURE TO OUR NORTH WILL CONTINUE TO KEEP VFR CONDITIONS
OVER CENTRAL SOUTH CAROLINA AND THE CENTRAL SAVANNAH RIVER AREA
THROUGH MUCH OF THE TAF FORECAST PERIOD.
LOW PRESSURE CURRENTLY CENTERED SOUTHWEST OF NEW ORLEANS IS FORECAST
TO MOVE NORTHEAST OVER THE NEXT 24 HOURS TO THE NORTHWEST FLORIDA
PANHANDLE BY SUNDAY AFTERNOON. MODEL GUIDANCE HAS BEEN SLOWING THE
PROGRESS AND THE INTENSITY OF THE SYSTEM OVER THE PAST SEVERAL MODEL
RUNS. LOOKS LIKE MVFR TO IFR FLYING CONDITIONS WILL BE DELAYED TO
LATER IN THE FORECAST PERIOD WITH THE GREATEST THREAT BEING LATE
SUNDAY AND SUNDAY NIGHT. WITH THIS IN MIND...SLOWED THE LOWERING
OF THE CEILING AND VISIBILITY WITH MVFR CONDITIONS OVERSPREADING
THE AREA LATE IN THE FORECAST PERIOD.
EXTENDED AVIATION OUTLOOK...WIDESPREAD MVFR OR IFR CONDITIONS WILL
LIKELY OCCUR LATE SUNDAY...SUNDAY NIGHT AND MONDAY. LOW PRESSURE
WILL MOVE ACROSS SOUTHERN GEORGIA AND THEN NORTHEAST UP THE SOUTH
CAROLINA COAST DURING THAT TIME PERIOD SPREADING LOW CEILINGS AND
VISIBILITY ACROSS THE AREA.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
000
FXUS62 KGSP 211530
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1030 AM EST SAT NOV 21 2009
.SYNOPSIS...
HIGH PRESSURE OVER THE REGION WILL SHIFT NORTH OVER THE WEEKEND.
THIS WILL ALLOW A LOW PRESSURE SYSTEM TO MOVE EAST ALONG THE GULF
COAST THEN NORTH ALONG THE CAROLINA COAST SUNDAY THROUGH MONDAY.
THE LOW IS EXPECTED TO REACH THE NEW ENGLAND COAST BY TUESDAY AS
WEAK HIGH PRESSURE REMAINS OVER THE SOUTHEAST STATES. ANOTHER COLD
FRONT OR COASTAL LOW COULD MOVE INTO THE AREA BY THE MIDDLE OF NEXT
WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
CURRENT FORECAST IS IN GOOD SHAPE. I INCREASED THE OPAQUE CLOUD
COVER TODAY BASED ON CURRENT TRENDS...BUT THAT/S ALL I NEEDED TO
TWEAK. PREVIOUS DISCUSSION FOLLOWS...
CURRENT IR SATELLITE IMAGERY INDICATES THAT CIRRUS SHIELD CONTINUES
TO STREAM IN FROM THE SOUTHWEST...AND IS EXPECTED TO CONTINUE
THROUGHOUT THE NEAR TERM PERIOD. MAIN FORECAST PROBLEM THROUGH
TONIGHT CENTERS AROUND THE DEVELOPING WEDGE AND CYCLOGENESIS OVER
THE NORTHERN GULF. CURRENT SUITE OF MODEL RUNS FAVOR MUCH SLOWER
TIMING OF DEEP LAYER MOISTURE SPREADING OVER TOP OF THE COLD DOME.
IN FACT...EVEN THE FASTER GFS SOLUTION SUPPORTS A DRY FORECAST
THROUGH 06Z. THEREFORE...I HAVE TRIMMED POPS SIGNIFICANTLY FEATURING
ONLY LOW END CHANCE POPS ACROSS THE SOUTHWESTERN THIRD OF THE
FA...SIMILAR TO THE SREF. AS IT STANDS NOW ONLY THE GFS BRINGS MUCH
IN THE WAY OF ISENTROPIC LIFT INTO THE AREA BY 12Z SO AS IT STANDS
EVEN THIS POP COULD BE A BIT OVERDONE. THE SURFACE HIGH SLIDES INTO
A MORE FAVORABLE WEDGE POSITION THROUGH THE AFTERNOON AND SHOULD BE
WELL IN PLACE BY MID TO LATE MORNING.
I HAVE BLENDED HIGH TEMPS DOWNWARD A BIT TODAY...MORE TOWARD MOS
GUIDANCE. WITH CONSIDERABLE HIGH CLOUDS IN PLACE...SHOULD HELP LIMIT
MAX TEMPS. EXPECT LOW 60S OUTSIDE THE MOUNTAINS...AND UPPER 50S IN
THE MOUNTAIN VALLEYS. LOWS WILL DIP INTO THE LOW TO MID 40S.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 230 AM EST SATURDAY...A SOUTHERN STREAM UPPER LOW WILL MOVE
FROM THE GULF STATES TO THE APPALACHIANS ON SUNDAY AND SUNDAY NIGHT
WHILE WEAKENING. ON MONDAY AND MONDAY NIGHT AND UPPER RIDGE
AMPLIFIES OVER THE SOUTHEAST. THE GFS CONTINUES TO BE FASTER TO
SPREAD MOISTURE AND ISENTROPIC UPGLIDE NORTHEAST ACROSS THE AREA ON
SUNDAY...AND CLOUD COVER AND POPS HAVE BEEN REDUCED TO FAVOR THE
SLOWER NAM/ECMWF SOLUTIONS. POPS HAVE BEEN INCREASED SUNDAY NIGHT
AND MONDAY TO INDICATE A SLOWER EVOLUTION OF COLD AIR DAMMING...
AND A MORE PROLONGED EVENT...WITH LESS OF A DECREASE OF CLOUDS ON
MONDAY NIGHT. SMALL POPS WILL EVEN BE CARRIED ALONG THE BLUE RIDGE
ESCARPMENT MONDAY NIGHT WHERE THE ECMWF INDICATED SOME LINGERING
MOIST UPSLOPE FLOW. MAXIMUM TEMPERATURES HAVE BEEN RAISED A BIT ON
SUNDAY...AND LOWERED ON MONDAY...TO INDICATE THE DELAYED ONSET OF
COLD AIR DAMMING...WITH MINIMUM RAISED SUNDAY NIGHT AND MONDAY
NIGHT. NONE OF THE MODELS HAS NEAR THE AMOUNT OF UPGLIDE OR UPSLOPE
FLOW...SO ONLY MODEST RAINFALL AMOUNTS WIL BE CARRIED...WITH SOME
TERRAIN ENHANCEMENT NEAR THE SOUTH AND SOUTHEAST FACING BLUE RIDGE
ESCARPMENT OF GA AND SC.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 315 AM SATURDAY...HPC CONTINUES TO PREFER THE ECMWF FOR THE
MEDIUM RANGE. THERE ARE DIFFERENCES BETWEEN IT AND THE GFS AND
GEM...WHICH HAVE SIMILAR SOLUTIONS. HOWEVER...THE 00Z ECMWF HAS
TRENDED TOWARD THE GFS AND GEM SOLUTIONS. GIVEN THESE DIFFERENCES
THE EXTENDED FCST REMAINS LOW CONFIDENCE.
THE MODELS AGREE THAT A CLOSED UPPER LOW OVER THE OVER THE PLAINS
MOVES EAST AS A STRONG SHORT WAVE DIVES IN BEHIND THE LOW CREATING
AN EASTERN US TROF. THIS WAVE THEN MERGES WITH OR TAKES THE PLACE OF
THE PREVIOUS LOW AS IT THEN MOVES OFF THE COAST. AT THE SFC...CAD
BEGINS TO ERODE...BUT THERE COULD BE SOME LINGERING PATCHY RAIN TUE
AND TUE NITE. THEN ANOTHER OCCLUDED FNT APPROACHES THE AREA WED AS A
GULF COAST LOW DEVELOPS. THE GFS/GEM KEEP THE FCST DRY AS THE DYING
OCCLUDED FNT HAS LITTLE MOISTURE AND THE COASTAL LOW REMAINS VERY
FAR SOUTH. THE ECMWF HAS MUCH MORE MOISTURE OVER THE AREA AS THE LOW
RIDES ALONG THE COAST. THE ECMWF THEN DRIES THINGS OUT THU AS THE
LOW MOVES UP THE EAST COAST AND AWAY FROM THE AREA. BOTH MDLS SHOW
SOME NW FLOW MOISTURE THU AND FRI. HOWEVER...THE GFS IS MUCH WETTER
AND COLDER SUGGESTING A P-TYPE OF SNOW. GIVEN ALL THIS
UNCERTAINTY...WILL KEEP POPS LIMITED TO SLIGHT CHC. TEMPS START OUT
ABOVE NORMAL THEN COOL BELOW NORMAL. KEPT MTN TEMPS ABOVE FREEZING
DURING THE PERIODS WITH PRECIPITATION...FOR A RAIN P-TYPE.
&&
.AVIATION /16Z SATURDAY THROUGH WEDNESDAY/...
AT KCLT AND ELSEWHERE...HIGH CLOUDS WILL REMAIN ACROSS THE AREA
THROUGH THE DAY...LEAVING ALL SITES WITH AN OVERCAST CIRRUS LAYER
FOR THE EARLY TAF PERIOD. A SURFACE HIGH WILL SLOWLY MOVE INTO A
BETTER COLD AIR DAMMING POSITION BY TONIGHT...AND WINDS WILL RESPOND
ACCORDINGLY GOING NELY...NLY AT KAVL...BY MID MORNING. EXPECT A SELY
WIND AT KAVL DURING THE AFTERNOON...RETURNING TO NLY DURING THE
EVENING. THE LATTER PART OF THE TAF PERIOD DOES PRESENT SOME
CHALLENGES MAINLY BECAUSE OF A CHANGE IN THE TIMING OF LOW CLOUDS
AND PRECIP FAVORED BY THE VARIOUS MODEL SOLUTIONS. EVEN THE FASTEST
MODEL SOLUTION...THE GFS...KEEPS THINGS DRY ACROSS THE CWA THROUGH
NEARLY 12Z AND ALSO KEEPS ANY CEILING RESTRICTIONS TO BEYOND THIS
TAF PERIOD. THEREFORE...WILL KEEP THINGS VFR AT ALL SITES...BUT WILL
BRING IN MID LEVEL CIGS AND SCT LOW VFR CLOUDS BY 06Z. LOW VFR CIG
IS POSSIBLE AT KAND BY THE END OF THE PERIOD...BUT WILL LIKELY HOLD
OFF UNTIL AFTER.
OUTLOOK...CLOUD CEILINGS WILL GRADUALLY LOWER SUNDAY MORNING WITH
MVFR CONDITIONS EXPECTED BY LATE MORNING. RAIN WILL DEVELOP OVER THE
REGION ON SUNDAY WITH WIDESPREAD IFR CIGS AND MVFR FOG EXPECTED TO
LAST THROUGH MOST OF MONDAY. FAIR AND DRY WEATHER IS THEN EXPECTED
BY LATE TUESDAY INTO WEDNESDAY.
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...RWH
NEAR TERM...BSH/MCAVOY
SHORT TERM...JAT
LONG TERM...RWH
AVIATION...BSH/RWH
000
FXUS62 KCHS 211506
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
1006 AM EST SAT NOV 21 2009
.SYNOPSIS...
HIGH PRES WILL REMAIN N OF THE REGION THROUGH TONIGHT. AN AREA OF LOW
PRES WILL TRACK ALONG THE GULF COAST STATES AND INTO THE ATLC OFF
THE SOUTHEAST GEORGIA COAST SUNDAY AND SUNDAY NIGHT. THIS SYSTEM
WILL THEN MOVE NE ALONG THE EASTERN SEABOARD...AS HIGH PRES HOLDS
IN PLACE INLAND. HIGH PRES WILL SLOWLY BECOME MORE DOMINANT FROM
MID-LATE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
MID AND HIGH CLOUDS WILL CONTINUE TO INCREASE FROM THE SW TODAY
AHEAD OF AN APPROACHING UPPER TROUGH. MEANWHILE THE LOW STRATUS
FROM THIS MORNING SHOULD SLOWLY BURN OFF...BUT LOW-LEVEL CLOUDS
WILL PROBABLY INCREASE LATE IN THE DAY AS ISENTROPIC LIFT BEGINS.
THERE WILL BE LITTLE IN THE WAY OF FORCING FOR PRECIP EXCEPT JUST
OFF THE CHARLESTON COUNTY COAST WHERE AN ISOLATED SHOWER COULD
DEVELOP IN THE COASTAL TROUGH. ONGOING FORECAST OF HIGHS IN THE
MIDDLE TO UPPER 60S LOOKED GOOD BASED ON LATEST TRENDS SO WE MADE
ONLY MINOR TWEAKS TO TODAY/S GRAPHICS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SUNDAY/...
THE VIGOROUS SOUTHERN STREAM SYSTEM WILL LIFT FROM SE TEXAS TODAY
INTO THE LOWER MISSISSIPPI VALLEY REGION BY 12Z ON SUNDAY. DYNAMIC
INFLUENCES WILL GUIDE SIGNIFICANT RAINS INTO WESTERN AND N GEORGIA
BY DAWN WITH ISENTROPIC LIFT AND DEEP MOISTURE GRADUALLY INCREASING
OVERNIGHT OVER OUR FORECAST AREA. THE GFS IS NOW A FASTER OUTLIER
IN SPREADING RAINS THROUGH OUR ENTIRE FORECAST AREA AFTER MIDNIGHT
TONIGHT. THE BAROCLINIC ZONE WILL LIKELY PERSIST OFF THE COAST AND
DEEP LAYERED CONVERGENCE AND UPPER FORCING WILL LIKELY INCITE
RAINFALL DEVELOPMENT SW OF THE SAVANNAH RIVER SHORTLY BEFORE
DAYBREAK ON SUNDAY. COASTAL SOUTH CAROLINA APPEARS TO BE BETWEEN
THE APPROACHING DYNAMICS AND THE OFFSHORE FRONTAL ZONE AND WE
TRIMMED POPS BACK TO A LOW END CHANCE LATE TONIGHT. CLOUDS AND
A LIGHT/STEADY NE FLOW SHOULD KEEP TEMPERATURES IN THE LOWER TO
MID 50S COASTAL AREAS WITH SOME UPPER 40S CLOSER TO THE CSRA AND
MIDLANDS WHERE THE SURFACE WEDGE WILL BE ENTRENCHED.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
MEDIUM RANGE GUIDANCE IS IN GOOD AGREEMENT THROUGH EARLY NEXT
WEEK...WITH SOLUTIONS THEN DIVERGING DURING THE LAST SEVERAL DAYS OF
THE EXTENDED FORECAST PERIOD. AS A RESULT...CONFIDENCE IS NEAR
NORMAL THROUGH MONDAY...THEN DROPS BELOW NORMAL TUESDAY THROUGH
FRIDAY.
GUIDANCE HAS COME INTO GOOD AGREEMENT BRINGING A WEAKENING WAVE OF
LOW PRESSURE ACROSS THE NORTHERN GULF COAST STATES SUNDAY AND
TRACKING ACROSS THE GEORGIA/FLORIDA BORDER SUNDAY NIGHT. AS THIS LOW
PASSES BY TO THE SOUTH OF THE FORECAST AREA...A WEDGE OF HIGH
PRESSURE WILL HOLD IN PLACE ACROSS MUCH OF THE EASTERN THIRD OF THE
COUNTRY. THE AREA OF LOW PRESSURE WILL THEN TRACK NORTHEASTWARD OFF
THE EASTERN SEA BOARD AND INTO THE SOUTHERN NEW ENGLAND MONDAY
THROUGH TUESDAY...HELPING TO RE-ENFORCE THE EXISTING HIGH PRESSURE
WEDGE ACROSS THE FORECAST AREA.
MODEL SOLUTIONS THEN REMAIN SPLIT ON DEGREE OF PHASING BETWEEN THE
NORTHERN AND SOUTHERN STREAM WEDNESDAY THROUGH THURSDAY...WITH THE
GFS AND CANADIAN SOLUTIONS SHOWING LITTLE PHASING. AS A
RESULT...THESE MODELS KEEP THE FORECAST AREA UNDER THE INFLUENCE OF
HIGH PRESSURE WITH LITTLE CHANCE FOR RAIN. ON THE OTHER-HAND...THE
ECMWF AND UKMET MODELS DEPICT THE TWO STREAMS PHASING...WHICH
RESULTS IN A WAVE OF LOW PRESSURE TRACKING THROUGH THE SOUTHEAST
STATES ALONG WITH RAIN CHANCES WEDNESDAY THROUGH THURSDAY. GUIDANCE
THEN COMES INTO AGREEMENT BUILDING HIGH PRESSURE INTO THE AREA
THURSDAY NIGHT AND FRIDAY.
AS FOR FORECAST DETAILS...WILL CARRY LIKELY/CATEGORICAL POPS SUNDAY
AND SUNDAY NIGHT AS GOOD FORCING FOR ASCENT ALONG WITH DEEP MOISTURE
AND ISENTROPIC UPGLIDE OVERSPREAD THE FORECAST AREA. MODEL SOLUTIONS
DEPICT SOME DECENT MID-LEVEL LAPSE RATES ON THE ORDER OF 6.5 C/KM
MOVING THROUGH SUNDAY AFTERNOON THROUGH SUNDAY EVENING. ALTHOUGH A
STRONG SURFACE HIGH PRESSURE WEDGE WILL BE IN PLACE...GIVEN THE
DEGREE OF FORCING MOVING OVERHEAD...CAN/T RULE OUT ELEVATED
CONVECTION...SO WILL CARRY THUNDER MENTION IN THE FORECAST AS WELL.
AS SURFACE HIGH PRESSURE WEDGE IS RE-ENFORCED MONDAY THROUGH TUESDAY
AS THE SURFACE AREA OF LOW PRESSURE LIFTS NORTHWARD TOWARD NEW
ENGLAND...NOT ANTICIPATING MUCH IF ANY CLEARING ACROSS THE FORECAST
AREA. MODEL TIME HEIGHT RELATIVE HUMIDITY CROSS SECTIONS INDICATE
THAT THE 1000-850 MB LAYER WILL REMAIN NEARLY SATURATED THROUGH THIS
PERIOD...SO WILL CARRY SLIGHT CHANCE/LOW CHANCE POPS AND MENTION OF
DRIZZLE ACROSS THE FORECAST AREA. HAVE SIGNIFICANTLY UNDERCUT MOS
GUIDANCE MAX TEMPERATURES AS WELL...AS LIGHT WIND FIELDS COMBINED
WITH THE LOW SUN ANGLE SHOULD LEAD TO PRIMARILY OVERCAST CONDITIONS
AND SMALL DIURNAL TEMPERATURE SWINGS.
FORECAST CONFIDENCE GOES DOWNHILL QUICKLY WEDNESDAY AND THURSDAY
WITH GUIDANCE SOLUTIONS SPLIT ON EVENTUAL PATTERN EVOLUTION. FOR NOW
WILL STICK WITH A SOLUTION CLOSE TO THE GFS AND CANADIAN SOLUTIONS
WHICH MAINTAINS GOOD FORECAST CONTINUITY AND AWAIT BETTER MODEL
AGREEMENT BEFORE MAKING ANY SWEEPING CHANGES. THIS RESULTS...IN A
RAIN FREE FORECAST WEDNESDAY THROUGH FRIDAY.
&&
.AVIATION /15Z SATURDAY THROUGH WEDNESDAY/...
KCHS...LIFR CIGS EXPANDED OVERNIGHT AND BLANKET THE CHARLESTON
AREA AT DAWN ALONG WITH VSBY IN THE 1-3NM RANGE JUST UNDER 100
FT CIGS. THE LATEST GFS LAMP GUIDANCE AND 06Z WRF BUFKIT SOUNDINGS
INDICATE THE LOW CLOUDS WILL TAKE SOME TIME TO DISPERSE AGAIN THIS
MORNING. BY EARLY AFTERNOON...LOW CLOUDS LIKELY OUT OF THE PICTURE
AND ONLY A MIX OF LAYERED CLOUDS FOR THE REMAINDER OF THE TAF CYCLE.
TONIGHT...INCREASING HIGHER CLOUDS EXPECTED TO INHIBIT WIDESPREAD
FOG/STRATUS DEVELOPMENT AND WINDS SHOULD STAY UP A BIT STRONGER
TONIGHT WITH SLIGHTLY LOWER SURFACE DEW POINTS POSSIBLE.
KSAV...STRATUS SHIELD HAS ADVANCED INTO SOUTHERN BEAUFORT AND
JASPER COUNTIES AND APPEARS TO HAVE A SLIGHTLY BETTER CHANCE
THAN YESTERDAY MORNING TO REACH THE SAVANNAH AIRPORT. CLOUD
PATTERN TRENDS HAVE BECOME DIFFICULT TO FOLLOW IN THE PAST HOUR
AS HIGH CLOUDS BLOCK THE VSBL PROGRESS OF THE LOWER CLOUDS ON
SATELLITE IMAGERY. WITH THE LATEST OBSERVATION CARRYING A FEW
STRATUS...WE CARRIED A COUPLE HOUR TEMPO OF IFR CIGS AT KSAV TO
BE ON THE SAFE SIDE. OTHERWISE...VFR CONDITIONS ANTICIPATED
THROUGH TONIGHT WITH A STEADY NE FLOW AND PLENTY OF MID AND HIGH
LEVEL CLOUDS ON TAP.
EXTENDED AVIATION OUTLOOK...MVFR OR LOWER CIGS AND VSBYS LIKELY
SUNDAY THROUGH TUE. VFR CONDITIONS MAY RETURN ON WED.
&&
.MARINE...
THE PRES GRADIENT WAS PINCHING PRE-DAWN FROM AROUND BUOY 41004 UP
TO THE BUOY 41013. NNE FLOW AVERAGING 10 TO 15 KT OVER OUR WATERS
THIS MORNING...EXCEPT COASTWARD FROM GRAYS REEF WHERE SPEEDS WERE
FAIRLY LIGHT IN A WEAKER GRADIENT. SEAS WERE ELEVATED BEYOND 40
NM OFF THE COAST ACCORDING TO STEADY WAVEWATCH OUTPUT AND FETCH
LENGTH AND PERSISTENCE PROGS. WE WILL CONTINUE WITH MARGINAL
SMALL CRAFT ADVISORY CONDITIONS...MAINLY FOR SEAS OVER OUR OUTER
GEORGIA WATERS. THE COASTAL CAROLINAS PRES GRADIENT WILL TIGHTEN
TONIGHT AND WITH STEADY NE FLOW...IT APPEARS SEAS WILL BUILD INTO
SCA RANGE OFF AT LEAST THE CHARLESTON COUNTY COAST OVERNIGHT. THE
MODELS COULD BE UNDERDONE WITH THE PINCHING AND FORECAST CONDITIONS
MAY TURN OUT SOMEWHAT OPTIMISTIC. OUTER GEORGIA WATERS WILL REMAIN
IN SCA CONDITIONS TONIGHT.
AN AREA OF LOW PRESSURE WILL TRACK EASTWARD ALONG THE NORTHERN GULF
COAST AND GEORGIA/FLORIDA BORDER REGION SUNDAY AND SUNDAY
NIGHT...THEN NORTHEASTWARD ALONG THE EASTERN SEABOARD AND INTO
SOUTHERN NEW ENGLAND MONDAY THROUGH TUESDAY. HIGH PRESSURE WILL THEN
BUILD IN FROM THE WEST ON WEDNESDAY.
EXPECT A FAIRLY STRONG PINCHED GRADIENT ACROSS THE WATERS SUNDAY AND
SUNDAY NIGHT...WITH SMALL CRAFT CONDITIONS CONTINUING ACROSS
PORTIONS OF THE WATERS. AS LOW PRESSURE PULLS AWAY FROM THE REGION
MONDAY...EXPECT IMPROVING CONDITIONS WITH WINDS AND SEAS REMAINING
BELOW SMALL CRAFT THRESHOLDS THROUGH WEDNESDAY.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 5 AM EST MONDAY FOR AMZ374.
SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 5 AM EST
MONDAY FOR AMZ350.
&&
$$
JRL
000
FXUS62 KCHS 211156
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
656 AM EST SAT NOV 21 2009
.SYNOPSIS...
HIGH PRES WILL REMAIN N OF THE REGION THROUGH TONIGHT. AN AREA OF LOW
PRES WILL TRACK ALONG THE GULF COAST STATES AND INTO THE ATLC OFF
THE SOUTHEAST GEORGIA COAST SUNDAY AND SUNDAY NIGHT. THIS SYSTEM
WILL THEN MOVE NE ALONG THE EASTERN SEABOARD...AS HIGH PRES HOLDS
IN PLACE INLAND. HIGH PRES WILL SLOWLY BECOME MORE DOMINANT FROM
MID-LATE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
STRATUS OVER THE ATLC WATERS OFF THE CAROLINA COAST EARLY THIS
MORNING WERE TRANSLATING SSW THROUGH OUR COASTAL SOUTH CAROLINA
ZONES PER LATEST SATELLITE TRENDS. WE UPDATED OUR FORECAST A SHORT
WHILE AGO TO INCLUDE SOME AREAS OF FOG TO THE E OF I-95...ESPECIALLY
AROUND THE CHARLESTON AREA. THERE IS STILL A WEAK BAROCLINIC
REGION OVER THE GULF STREAM AND THE PRESENCE OF A MID LEVEL SHORT
WAVE SUGGESTS WEAK SURFACE LOW PRES AND CONVERGENCE WILL REMAIN E
OF THE SOUTH CAROLINA COAST TODAY. AN ISOLATED SHOWER MAY BRUSH
COASTAL CHARLESTON COUNTY AT SOME POINT TODAY...OTHERWISE WE
MAINTAINED A DRY FORECAST WITH A FLAVOR FOR INCREASING CLOUDS OR
JUST MOSTLY CLOUDY MOST AREAS. TEMPERATURES...WE TRENDED A BIT
COOLER TODAY WITH 00Z GUIDANCE 3 HOUR NUMBERS DOWN FROM PREVIOUS
RUNS ON ALL MODELS. OVERALL HIGHS SHOULD TOP OUT IN THE MID 60S
WITH SOME NEAR 70 READINGS POSSIBLE IN PARTS OF INLAND SE GEORGIA
CLOSER TO THE ALTAMAHA REGION.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SUNDAY/...
THE VIGOROUS SOUTHERN STREAM SYSTEM WILL LIFT FROM SE TEXAS TODAY
INTO THE LOWER MISSISSIPPI VALLEY REGION BY 12Z ON SUNDAY. DYNAMIC
INFLUENCES WILL GUIDE SIGNIFICANT RAINS INTO WESTERN AND N GEORGIA
BY DAWN WITH ISENTROPIC LIFT AND DEEP MOISTURE GRADUALLY INCREASING
OVERNIGHT OVER OUR FORECAST AREA. THE GFS IS NOW A FASTER OUTLIER
IN SPREADING RAINS THROUGH OUR ENTIRE FORECAST AREA AFTER MIDNIGHT
TONIGHT. THE BAROCLINIC ZONE WILL LIKELY PERSIST OFF THE COAST AND
DEEP LAYERED CONVERGENCE AND UPPER FORCING WILL LIKELY INCITE
RAINFALL DEVELOPMENT SW OF THE SAVANNAH RIVER SHORTLY BEFORE
DAYBREAK ON SUNDAY. COASTAL SOUTH CAROLINA APPEARS TO BE BETWEEN
THE APPROACHING DYNAMICS AND THE OFFSHORE FRONTAL ZONE AND WE
TRIMMED POPS BACK TO A LOW END CHANCE LATE TONIGHT. CLOUDS AND
A LIGHT/STEADY NE FLOW SHOULD KEEP TEMPERATURES IN THE LOWER TO
MID 50S COASTAL AREAS WITH SOME UPPER 40S CLOSER TO THE CSRA AND
MIDLANDS WHERE THE SURFACE WEDGE WILL BE ENTRENCHED.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
MEDIUM RANGE GUIDANCE IS IN GOOD AGREEMENT THROUGH EARLY NEXT
WEEK...WITH SOLUTIONS THEN DIVERGING DURING THE LAST SEVERAL DAYS OF
THE EXTENDED FORECAST PERIOD. AS A RESULT...CONFIDENCE IS NEAR
NORMAL THROUGH MONDAY...THEN DROPS BELOW NORMAL TUESDAY THROUGH
FRIDAY.
GUIDANCE HAS COME INTO GOOD AGREEMENT BRINGING A WEAKENING WAVE OF
LOW PRESSURE ACROSS THE NORTHERN GULF COAST STATES SUNDAY AND
TRACKING ACROSS THE GEORGIA/FLORIDA BORDER SUNDAY NIGHT. AS THIS LOW
PASSES BY TO THE SOUTH OF THE FORECAST AREA...A WEDGE OF HIGH
PRESSURE WILL HOLD IN PLACE ACROSS MUCH OF THE EASTERN THIRD OF THE
COUNTRY. THE AREA OF LOW PRESSURE WILL THEN TRACK NORTHEASTWARD OFF
THE EASTERN SEA BOARD AND INTO THE SOUTHERN NEW ENGLAND MONDAY
THROUGH TUESDAY...HELPING TO RE-ENFORCE THE EXISTING HIGH PRESSURE
WEDGE ACROSS THE FORECAST AREA.
MODEL SOLUTIONS THEN REMAIN SPLIT ON DEGREE OF PHASING BETWEEN THE
NORTHERN AND SOUTHERN STREAM WEDNESDAY THROUGH THURSDAY...WITH THE
GFS AND CANADIAN SOLUTIONS SHOWING LITTLE PHASING. AS A
RESULT...THESE MODELS KEEP THE FORECAST AREA UNDER THE INFLUENCE OF
HIGH PRESSURE WITH LITTLE CHANCE FOR RAIN. ON THE OTHER-HAND...THE
ECMWF AND UKMET MODELS DEPICT THE TWO STREAMS PHASING...WHICH
RESULTS IN A WAVE OF LOW PRESSURE TRACKING THROUGH THE SOUTHEAST
STATES ALONG WITH RAIN CHANCES WEDNESDAY THROUGH THURSDAY. GUIDANCE
THEN COMES INTO AGREEMENT BUILDING HIGH PRESSURE INTO THE AREA
THURSDAY NIGHT AND FRIDAY.
AS FOR FORECAST DETAILS...WILL CARRY LIKELY/CATEGORICAL POPS SUNDAY
AND SUNDAY NIGHT AS GOOD FORCING FOR ASCENT ALONG WITH DEEP MOISTURE
AND ISENTROPIC UPGLIDE OVERSPREAD THE FORECAST AREA. MODEL SOLUTIONS
DEPICT SOME DECENT MID-LEVEL LAPSE RATES ON THE ORDER OF 6.5 C/KM
MOVING THROUGH SUNDAY AFTERNOON THROUGH SUNDAY EVENING. ALTHOUGH A
STRONG SURFACE HIGH PRESSURE WEDGE WILL BE IN PLACE...GIVEN THE
DEGREE OF FORCING MOVING OVERHEAD...CAN/T RULE OUT ELEVATED
CONVECTION...SO WILL CARRY THUNDER MENTION IN THE FORECAST AS WELL.
AS SURFACE HIGH PRESSURE WEDGE IS RE-ENFORCED MONDAY THROUGH TUESDAY
AS THE SURFACE AREA OF LOW PRESSURE LIFTS NORTHWARD TOWARD NEW
ENGLAND...NOT ANTICIPATING MUCH IF ANY CLEARING ACROSS THE FORECAST
AREA. MODEL TIME HEIGHT RELATIVE HUMIDITY CROSS SECTIONS INDICATE
THAT THE 1000-850 MB LAYER WILL REMAIN NEARLY SATURATED THROUGH THIS
PERIOD...SO WILL CARRY SLIGHT CHANCE/LOW CHANCE POPS AND MENTION OF
DRIZZLE ACROSS THE FORECAST AREA. HAVE SIGNIFICANTLY UNDERCUT MOS
GUIDANCE MAX TEMPERATURES AS WELL...AS LIGHT WIND FIELDS COMBINED
WITH THE LOW SUN ANGLE SHOULD LEAD TO PRIMARILY OVERCAST CONDITIONS
AND SMALL DIURNAL TEMPERATURE SWINGS.
FORECAST CONFIDENCE GOES DOWNHILL QUICKLY WEDNESDAY AND THURSDAY
WITH GUIDANCE SOLUTIONS SPLIT ON EVENTUAL PATTERN EVOLUTION. FOR NOW
WILL STICK WITH A SOLUTION CLOSE TO THE GFS AND CANADIAN SOLUTIONS
WHICH MAINTAINS GOOD FORECAST CONTINUITY AND AWAIT BETTER MODEL
AGREEMENT BEFORE MAKING ANY SWEEPING CHANGES. THIS RESULTS...IN A
RAIN FREE FORECAST WEDNESDAY THROUGH FRIDAY.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
KCHS...LIFR CIGS EXPANDED OVERNIGHT AND BLANKET THE CHARLESTON
AREA AT DAWN ALONG WITH VSBY IN THE 1-3NM RANGE JUST UNDER 100
FT CIGS. THE LATEST GFS LAMP GUIDANCE AND 06Z WRF BUFKIT SOUNDINGS
INDICATE THE LOW CLOUDS WILL TAKE SOME TIME TO DISPERSE AGAIN THIS
MORNING. BY EARLY AFTERNOON...LOW CLOUDS LIKELY OUT OF THE PICTURE
AND ONLY A MIX OF LAYERED CLOUDS FOR THE REMAINDER OF THE TAF CYCLE.
TONIGHT...INCREASING HIGHER CLOUDS EXPECTED TO INHIBIT WIDESPREAD
FOG/STRATUS DEVELOPMENT AND WINDS SHOULD STAY UP A BIT STRONGER
TONIGHT WITH SLIGHTLY LOWER SURFACE DEW POINTS POSSIBLE.
KSAV...STRATUS SHIELD HAS ADVANCED INTO SOUTHERN BEAUFORT AND
JASPER COUNTIES AND APPEARS TO HAVE A SLIGHTLY BETTER CHANCE
THAN YESTERDAY MORNING TO REACH THE SAVANNAH AIRPORT. CLOUD
PATTERN TRENDS HAVE BECOME DIFFICULT TO FOLLOW IN THE PAST HOUR
AS HIGH CLOUDS BLOCK THE VSBL PROGRESS OF THE LOWER CLOUDS ON
SATELLITE IMAGERY. WITH THE LATEST OBSERVATION CARRYING A FEW
STRATUS...WE CARRIED A COUPLE HOUR TEMPO OF IFR CIGS AT KSAV TO
BE ON THE SAFE SIDE. OTHERWISE...VFR CONDITIONS ANTICIPATED
THROUGH TONIGHT WITH A STEADY NE FLOW AND PLENTY OF MID AND HIGH
LEVEL CLOUDS ON TAP.
EXTENDED AVIATION OUTLOOK...MVFR OR LOWER CIGS AND VSBYS LIKELY
SUNDAY THROUGH TUE. VFR CONDITIONS MAY RETURN ON WED.
&&
.MARINE...
THE PRES GRADIENT WAS PINCHING PRE-DAWN FROM AROUND BUOY 41004 UP
TO THE BUOY 41013. NNE FLOW AVERAGING 10 TO 15 KT OVER OUR WATERS
THIS MORNING...EXCEPT COASTWARD FROM GRAYS REEF WHERE SPEEDS WERE
FAIRLY LIGHT IN A WEAKER GRADIENT. SEAS WERE ELEVATED BEYOND 40
NM OFF THE COAST ACCORDING TO STEADY WAVEWATCH OUTPUT AND FETCH
LENGTH AND PERSISTENCE PROGS. WE WILL CONTINUE WITH MARGINAL
SMALL CRAFT ADVISORY CONDITIONS...MAINLY FOR SEAS OVER OUR OUTER
GEORGIA WATERS. THE COASTAL CAROLINAS PRES GRADIENT WILL TIGHTEN
TONIGHT AND WITH STEADY NE FLOW...IT APPEARS SEAS WILL BUILD INTO
SCA RANGE OFF AT LEAST THE CHARLESTON COUNTY COAST OVERNIGHT. THE
MODELS COULD BE UNDERDONE WITH THE PINCHING AND FORECAST CONDITIONS
MAY TURN OUT SOMEWHAT OPTIMISTIC. OUTER GEORGIA WATERS WILL REMAIN
IN SCA CONDITIONS TONIGHT.
AN AREA OF LOW PRESSURE WILL TRACK EASTWARD ALONG THE NORTHERN GULF
COAST AND GEORGIA/FLORIDA BORDER REGION SUNDAY AND SUNDAY
NIGHT...THEN NORTHEASTWARD ALONG THE EASTERN SEABOARD AND INTO
SOUTHERN NEW ENGLAND MONDAY THROUGH TUESDAY. HIGH PRESSURE WILL THEN
BUILD IN FROM THE WEST ON WEDNESDAY.
EXPECT A FAIRLY STRONG PINCHED GRADIENT ACROSS THE WATERS SUNDAY AND
SUNDAY NIGHT...WITH SMALL CRAFT CONDITIONS CONTINUING ACROSS
PORTIONS OF THE WATERS. AS LOW PRESSURE PULLS AWAY FROM THE REGION
MONDAY...EXPECT IMPROVING CONDITIONS WITH WINDS AND SEAS REMAINING
BELOW SMALL CRAFT THRESHOLDS THROUGH WEDNESDAY.
&&
.TIDES/COASTAL FLOODING...
TIDES AT DOWNTOWN CHARLESTON STILL RUNNING OVER 1 FT ABOVE PREDICTED
LEVELS. WE ARE WATCHING THE HIGH TIDE FOR LATER THIS MORNING...BUT
CURRENT INDICATIONS SUGGEST IT WILL FALL SHY OF COASTAL FLOOD ADVISORY
CRITERIA...BUT NOT BY MUCH.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 5 AM EST MONDAY FOR AMZ374.
SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 5 AM EST
MONDAY FOR AMZ350.
&&
$$
000
FXUS62 KCAE 211144
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
644 AM EST SAT NOV 21 2009
.SYNOPSIS...
HIGH PRESSURE OVER THE REGION TODAY WILL WEAKEN TONIGHT. LOW
PRESSURE WILL MOVE EAST ALONG THE GULF COAST TONIGHT AND SPREAD
RAIN TO THE AREA SUNDAY AND SUNDAY NIGHT. THE LOW WILL BEGIN TO
MOVE AWAY MONDAY AND THE CHANCES OF RAIN WILL DECREASE. HIGH
PRESSURE WILL BUILD IN MONDAY NIGHT AND TUESDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
HIGH PRESSURE WILL MOVE EAST AND CLOUDS WILL INCREASE FROM THE
SOUTH AS A LOW PRESSURE AREA MOVES TOWARD THE REGION. CONDITIONS
WILL REMAIN DRY TODAY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY/...
AN APPROACHING LOW PRESSURE AREA WILL SPREAD CLOUDS AND RAIN OVER
THE REGION LATE TONIGHT AND SUNDAY. THE RAIN WILL CONTINUE SUNDAY
NIGHT. THE LOW WILL MOVE OFFSHORE AND AWAY MONDAY DECREASE THE
CHANCES OF RAIN. THE RAIN SHOULD BE GONE LATE IN THE DAY MONDAY.
COOL TEMPERATURES ARE EXPECTED WITH SUNDAY HIGHS IN THE LOWER 50S
AND MONDAY HIGHS IN THE LOWER 60S. QPF AMOUNTS SHOULD BE AROUND
ONE INCH.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
IN GOOD AGREEMENT WITH LONG RANGE MODELS BRINGING LONG WAVE TROUGH
PATTERN BACK TO THE EAST. THIS SHOULD INCREASE NORTHWEST WIND FLOW
AT THE SURFACE AS A COUPLE OF DRY COLD FRONTS SWEEP THROUGH THE
REGION. THIS WILL ALSO GIVE THE AREA COOLER TEMPERATURES. HIGHS IN
THE MID 60S TUESDAY AND WEDNESDAY COOL TO NEAR 60 THANKSGIVING
DAY AND BLACK FRIDAY. OVERNIGHT LOWS IN THE 40S START OF PERIOD
LOWER TO THE 30S BY FRIDAY MORNING.
&&
.AVIATION /12Z SATURDAY THROUGH THURSDAY/...
PLENTY OF MID/HIGH LEVEL CLOUDS CONTINUE TO SPREAD NEWD IN ADVANCE
OF AN APPROACHING GULF LOW THIS MORNING. THIS HAS INHIBITED MUCH OF
THE FOG FORMATION WITH MOST SITES REPORTING VFR CONDITIONS.
ALTHOUGH CLOUDINESS WILL CONTINUE TO GRADUALLY THICKEN AND LOWER
THROUGHOUT THE FORECAST PERIOD...EXPECT VFR CONDITIONS TO PERSIST
THROUGH 12Z SUNDAY MORNING. BOTH NAM/GFS LOOK TO HOLD OFF ANY
PCPN...ESPECIALLY ACRS THE CSRA UNTIL ARND/JUST AFTER 12. FOR NOW
WILL NOT MENTION ANY PCPN IN FORECASTS.
EXTENDED AVIATION OUTLOOK...WIDESPREAD MVFR OR IFR CONDITIONS WILL
LIKELY OCCUR LATE SUNDAY...SUNDAY NIGHT AND INTO MONDAY. CONDITIONS
ASSOCIATED WITH AN AREA OF LOW PRESSURE THAT IS EXPECTED TO MOVE
NORTHEASTWARD FROM THE GULF OF MEXICO THROUGH THE EARLY PORTION OF
THE EXTENDED OUTLOOK.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
000
FXUS62 KGSP 211139
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
639 AM EST SAT NOV 21 2009
.SYNOPSIS...
HIGH PRESSURE WILL REMAIN OVER THE REGION THROUGH MONDAY. A LOW
PRESSURE SYSTEM WILL MOVE EAST ALONG THE GULF COAST THROUGH SUNDAY
THEN NORTH ALONG THE CAROLINA COAST MONDAY. THIS LOW IS EXPECTED TO
REACH THE NEW ENGLAND COAST TUESDAY AS WEAK HIGH PRESSURE REMAINS
OVER THE SOUTHEAST STATES. ANOTHER COLD FRONT OR COASTAL LOW COULD
MOVE INTO THE AREA BY THE MIDDLE OF NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
CURRENT IR SATELLITE IMAGERY INDICATES THAT CIRRUS SHIELD CONTINUES
TO STREAM IN FROM THE SOUTHWEST...AND IS EXPECTED TO CONTINUE
THROUGHOUT THE NEAR TERM PERIOD. MAIN FORECAST PROBLEM THROUGH
TONIGHT CENTERS AROUND THE DEVELOPING WEDGE AND CYCLOGENESIS OVER
THE NORTHERN GULF. CURRENT SUITE OF MODEL RUNS FAVOR MUCH SLOWER
TIMING OF DEEP LAYER MOISTURE SPREADING OVER TOP OF THE COLD DOME. IN
FACT...EVEN THE FASTER GFS SOLUTION SUPPORTS A DRY FORECAST THROUGH
06Z. THEREFORE...I HAVE TRIMMED POPS SIGNIFICANTLY FEATURING ONLY
LOW END CHANCE POPS ACROSS THE SOUTHWESTERN THIRD OF THE
FA...SIMILAR TO THE SREF. AS IT STANDS NOW ONLY THE GFS BRINGS MUCH
IN THE WAY OF ISENTROPIC LIFT INTO THE AREA BY 12Z SO AS IT STANDS
EVEN THIS POP COULD BE A BIT OVERDONE. THE SURFACE HIGH SLIDES INTO
A MORE FAVORABLE WEDGE POSITION THROUGH THE AFTERNOON AND SHOULD BE
WELL IN PLACE BY MID TO LATE MORNING.
I HAVE BLENDED HIGH TEMPS DOWNWARD A BIT TODAY...MORE TOWARD MOS
GUIDANCE. WITH CONSIDERABLE HIGH CLOUDS IN PLACE...SHOULD HELP LIMIT
MAX TEMPS. EXPECT LOW 60S OUTSIDE THE MOUNTAINS...AND UPPER 50S IN
THE MOUNTAIN VALLEYS. LOWS WILL DIP INTO THE LOW TO MID 40S.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 230 AM EST SATURDAY...A SOUTHERN STREAM UPPER LOW WILL MOVE
FROM THE GULF STATES TO THE APPALACHIANS ON SUNDAY AND SUNDAY NIGHT
WHILE WEAKENING. ON MONDAY AND MONDAY NIGHT AND UPPER RIDGE
AMPLIFIES OVER THE SOUTHEAST. THE GFS CONTINUES TO BE FASTER TO
SPREAD MOISTURE AND ISENTROPIC UPGLIDE NORTHEAST ACROSS THE AREA ON
SUNDAY...AND CLOUD COVER AND POPS HAVE BEEN REDUCED TO FAVOR THE
SLOWER NAM/ECMWF SOLUTIONS. POPS HAVE BEEN INCREASED SUNDAY NIGHT
AND MONDAY TO INDICATE A SLOWER EVOLUTION OF COLD AIR DAMMING...
AND A MORE PROLONGED EVENT...WITH LESS OF A DECREASE OF CLOUDS ON
MONDAY NIGHT. SMALL POPS WILL EVEN BE CARRIED ALONG THE BLUE RIDGE
ESCARPMENT MONDAY NIGHT WHERE THE ECMWF INDICATED SOME LINGERING
MOIST UPSLOPE FLOW. MAXIMUM TEMPERATURES HAVE BEEN RAISED A BIT ON
SUNDAY...AND LOWERED ON MONDAY...TO INDICATE THE DELAYED ONSET OF
COLD AIR DAMMING...WITH MINIMUM RAISED SUNDAY NIGHT AND MONDAY
NIGHT. NONE OF THE MODELS HAS NEAR THE AMOUNT OF UPGLIDE OR UPSLOPE
FLOW...SO ONLY MODEST RAINFALL AMOUNTS WIL BE CARRIED...WITH SOME
TERRAIN ENHANCEMENT NEAR THE SOUTH AND SOUTHEAST FACING BLUE RIDGE
ESCARPMENT OF GA AND SC.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 315 AM SATURDAY...HPC CONTINUES TO PREFER THE ECMWF FOR THE
MEDIUM RANGE. THERE ARE DIFFERENCES BETWEEN IT AND THE GFS AND
GEM...WHICH HAVE SIMILAR SOLUTIONS. HOWEVER...THE 00Z ECMWF HAS
TRENDED TOWARD THE GFS AND GEM SOLUTIONS. GIVEN THESE DIFFERENCES
THE EXTENDED FCST REMAINS LOW CONFIDENCE.
THE MODELS AGREE THAT A CLOSED UPPER LOW OVER THE OVER THE PLAINS
MOVES EAST AS A STRONG SHORT WAVE DIVES IN BEHIND THE LOW CREATING
AN EASTERN US TROF. THIS WAVE THEN MERGES WITH OR TAKES THE PLACE OF
THE PREVIOUS LOW AS IT THEN MOVES OFF THE COAST. AT THE SFC...CAD
BEGINS TO ERODE...BUT THERE COULD BE SOME LINGERING PATCHY RAIN TUE
AND TUE NITE. THEN ANOTHER OCCLUDED FNT APPROACHES THE AREA WED AS A
GULF COAST LOW DEVELOPS. THE GFS/GEM KEEP THE FCST DRY AS THE DYING
OCCLUDED FNT HAS LITTLE MOISTURE AND THE COASTAL LOW REMAINS VERY
FAR SOUTH. THE ECMWF HAS MUCH MORE MOISTURE OVER THE AREA AS THE LOW
RIDES ALONG THE COAST. THE ECMWF THEN DRIES THINGS OUT THU AS THE
LOW MOVES UP THE EAST COAST AND AWAY FROM THE AREA. BOTH MDLS SHOW
SOME NW FLOW MOISTURE THU AND FRI. HOWEVER...THE GFS IS MUCH WETTER
AND COLDER SUGGESTING A P-TYPE OF SNOW. GIVEN ALL THIS
UNCERTAINTY...WILL KEEP POPS LIMITED TO SLIGHT CHC. TEMPS START OUT
ABOVE NORMAL THEN COOL BELOW NORMAL. KEPT MTN TEMPS ABOVE FREEZING
DURING THE PERIODS WITH PRECIPITATION...FOR A RAIN P-TYPE.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
AT KCLT AND ELSEWHERE...HIGH CLOUDS WILL REMAIN ACROSS THE AREA
THROUGH THE DAY...LEAVING ALL SITES WITH AN OVERCAST CIRRUS LAYER
FOR THE EARLY TAF PERIOD. A SURFACE HIGH WILL SLOWLY MOVE INTO A
BETTER COLD AIR DAMMING POSITION BY TONIGHT...AND WINDS WILL RESPOND
ACCORDINGLY GOING NELY...NLY AT KAVL...BY MID MORNING. EXPECT A SELY
WIND AT KAVL DURING THE AFTERNOON...RETURNING TO NLY DURING THE
EVENING. THE LATTER PART OF THE TAF PERIOD DOES PRESENT SOME
CHALLENGES MAINLY BECAUSE OF A CHANGE IN THE TIMING OF LOW CLOUDS
AND PRECIP FAVORED BY THE VARIOUS MODEL SOLUTIONS. EVEN THE FASTEST
MODEL SOLUTION...THE GFS...KEEPS THINGS DRY ACROSS THE CWA THROUGH
NEARLY 12Z AND ALSO KEEPS ANY CEILING RESTRICTIONS TO BEYOND THIS
TAF PERIOD. THEREFORE...WILL KEEP THINGS VFR AT ALL SITES...BUT WILL
BRING IN MID LEVEL CIGS AND SCT LOW VFR CLOUDS BY 06Z. LOW VFR CIG
IS POSSIBLE AT KAND BY THE END OF THE PERIOD...BUT WILL LIKELY HOLD
OFF UNTIL AFTER.
OUTLOOK...CLOUD CEILINGS WILL GRADUALLY LOWER SUNDAY MORNING WITH
MVFR CONDITIONS EXPECTED BY LATE MORNING. RAIN WILL DEVELOP OVER THE
REGION ON SUNDAY WITH WIDESPREAD IFR CIGS AND MVFR FOG EXPECTED TO
LAST THROUGH MOST OF MONDAY. FAIR AND DRY WEATHER IS THEN EXPECTED
BY LATE TUESDAY INTO WEDNESDAY.
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...RWH
NEAR TERM...BSH
SHORT TERM...JAT
LONG TERM...RWH
AVIATION...BSH/RWH
000
FXUS62 KCAE 210901
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
401 AM EST SAT NOV 21 2009
.SYNOPSIS...
HIGH PRESSURE OVER THE REGION TODAY WILL WEAKEN TONIGHT. LOW
PRESSURE WILL MOVE EAST ALONG THE GULF COAST TONIGHT AND SPREAD
RAIN TO THE AREA SUNDAY AND SUNDAY NIGHT. THE LOW WILL BEGIN TO
MOVE AWAY MONDAY AND THE CHANCES OF RAIN WILL DECREASE. HIGH
PRESSURE WILL BUILD IN MONDAY NIGHT AND TUESDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
HIGH PRESSURE WILL MOVE EAST AND CLOUDS WILL INCREASE FROM THE
SOUTH AS A LOW PRESSURE AREA MOVES TOWARD THE REGION. CONDITIONS
WILL REMAIN DRY TODAY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY/...
AN APPROACHING LOW PRESSURE AREA WILL SPREAD CLOUDS AND RAIN OVER
THE REGION LATE TONIGHT AND SUNDAY. THE RAIN WILL CONTINUE SUNDAY
NIGHT. THE LOW WILL MOVE OFFSHORE AND AWAY MONDAY DECREASE THE
CHANCES OF RAIN. THE RAIN SHOULD BE GONE LATE IN THE DAY MONDAY.
COOL TEMPERATURES ARE EXPECTED WITH SUNDAY HIGHS IN THE LOWER 50S
AND MONDAY HIGHS IN THE LOWER 60S. QPF AMOUNTS SHOULD BE AROUND
ONE INCH.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
IN GOOD AGREEMENT WITH LONG RANGE MODELS BRINGING LONG WAVE TROUGH
PATTERN BACK TO THE EAST. THIS SHOULD INCREASE NORTHWEST WIND FLOW
AT THE SURFACE AS A COUPLE OF DRY COLD FRONTS SWEEP THROUGH THE
REGION. THIS WILL ALSO GIVE THE AREA COOLER TEMPERATURES. HIGHS IN
THE MID 60S TUESDAY AND WEDNESDAY COOL TO NEAR 60 THANKSGIVING
DAY AND BLACK FRIDAY. OVERNIGHT LOWS IN THE 40S START OF PERIOD
LOWER TO THE 30S BY FRIDAY MORNING.
&&
.AVIATION /09Z SATURDAY THROUGH WEDNESDAY/...
GOOD RADIATING CONDITIONS THIS EVENING HAS ALLOWED TEMPERATURES TO
FALL INTO THE MID AND UPPER 40S AT CAE...CUB AND AGS. TEMPS NEAR 50
AT OGB AND MID 50S DNL. HIGH CLOUDS IN ADVANCE OF AN APPROACHING
GULF LOW MAY INHIBIT RADIATION FOR THE REMAINDER OF THE NIGHT. STILL
EXPECT FOG TO DEVELOP AGAIN TONIGHT SIMILAR TO LAST NIGHT...MAINLY
DURING THE 09Z TO 14Z PERIOD WITH PREVAILING MVFR CONDITIONS AND
TEMPO IFR. DNL MAY REMAIN VFR THROUGH THE NIGHT AS LIGHT WIND AND
MIXING WILL LIKELY PREVENT FOG FORMATION.
CONDITIONS SHOULD RETURN TO VFR ALL SITES AFTER 14Z WITH ONLY
THICKENING HIGH TO MID LEVEL CLOUDS FOR THE REMAINDER OF THE DAY
IN ADVANCE OF THE APPROACHING GULF LOW PRESSURE SYSTEM. FOR NOW
EXPECT RAIN FROM THIS SYSTEM TO ARRIVE AFTER 210600. THE FIRST
SITES TO BE AFFECTED BY RAIN WOULD BE AGS AND DNL.
EXTENDED AVIATION OUTLOOK...WIDESPREAD MVFR OR IFR CONDITIONS
WILL LIKELY OCCUR LATE SATURDAY NIGHT AND SUNDAY ASSOCIATED WITH
AN AREA OF LOW PRESSURE EXPECTED TO MOVE NORTHEASTWARD FROM THE
GULF OF MEXICO.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
SYNOPSIS...07
NEAR TERM...07
SHORT TERM...07
LONG TERM...07
AVIATION...77
000
FXUS62 KCHS 210856
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
356 AM EST SAT NOV 21 2009
.SYNOPSIS...
HIGH PRES WILL REMAIN N OF THE REGION THROUGH TONIGHT. AN AREA OF LOW
PRES WILL TRACK ALONG THE GULF COAST STATES AND INTO THE ATLC OFF
THE SOUTHEAST GEORGIA COAST SUNDAY AND SUNDAY NIGHT. THIS SYSTEM
WILL THEN MOVE NE ALONG THE EASTERN SEABOARD...AS HIGH PRES HOLDS
IN PLACE INLAND. HIGH PRES WILL SLOWLY BECOME MORE DOMINANT FROM
MID-LATE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
LOW CLOUDS OVER THE ATLC WATERS OFF THE CAROLINA COAST EARLY THIS
MORNING WERE TRANSLATING WSW INTO OUR COASTAL SOUTH CAROLINA ZONES
PER LATEST SATELLITE TRENDS. THERE IS STILL A WEAK BAROCLINIC REGION
OVER THE GULF STREAM AND THE PRESENCE OF A MID LEVEL SHORT WAVE
SUGGESTS WEAK SURFACE LOW PRES AND CONVERGENCE WILL REMAIN E OF THE
SOUTH CAROLINA COAST TODAY. AN ISOLATED SHOWER MAY BRUSH COASTAL
CHARLESTON COUNTY AT SOME POINT TODAY...OTHERWISE WE MAINTAINED A
DRY FORECAST WITH A FLAVOR FOR INCREASING CLOUDS OR JUST MOSTLY
CLOUDY MOST AREAS. TEMPERATURES...WE TRENDED A BIT COOLER TODAY WITH
00Z GUIDANCE 3 HOUR NUMBERS DOWN FROM PREVIOUS RUNS ON ALL
MODELS. OVERALL HIGHS SHOULD TOP OUT IN THE MID 60S WITH SOME NEAR
70 READINGS POSSIBLE IN PARTS OF INLAND SE GEORGIA CLOSER TO THE
ALTAMAHA REGION.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SUNDAY/...
THE VIGOROUS SOUTHERN STREAM SYSTEM WILL LIFT FROM SE TEXAS TODAY
INTO THE LOWER MISSISSIPPI VALLEY REGION BY 12Z ON SUNDAY. DYNAMIC
INFLUENCES WILL GUIDE SIGNIFICANT RAINS INTO WESTERN AND N GEORGIA
BY DAWN WITH ISENTROPIC LIFT AND DEEP MOISTURE GRADUALLY INCREASING
OVERNIGHT OVER OUR FORECAST AREA. THE GFS IS NOW A FASTER OUTLIER
IN SPREADING RAINS THROUGH OUR ENTIRE FORECAST AREA AFTER MIDNIGHT
TONIGHT. THE BAROCLINIC ZONE WILL LIKELY PERSIST OFF THE COAST AND
DEEP LAYERED CONVERGENCE AND UPPER FORCING WILL LIKELY INCITE
RAINFALL DEVELOPMENT SW OF THE SAVANNAH RIVER SHORTLY BEFORE
DAYBREAK ON SUNDAY. COASTAL SOUTH CAROLINA APPEARS TO BE BETWEEN
THE APPROACHING DYNAMICS AND THE OFFSHORE FRONTAL ZONE AND WE
TRIMMED POPS BACK TO A LOW END CHANCE LATE TONIGHT. CLOUDS AND
A LIGHT/STEADY NE FLOW SHOULD KEEP TEMPERATURES IN THE LOWER TO
MID 50S COASTAL AREAS WITH SOME UPPER 40S CLOSER TO THE CSRA AND
MIDLANDS WHERE THE SURFACE WEDGE WILL BE ENTRENCHED.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
MEDIUM RANGE GUIDANCE IS IN GOOD AGREEMENT THROUGH EARLY NEXT
WEEK...WITH SOLUTIONS THEN DIVERGING DURING THE LAST SEVERAL DAYS OF
THE EXTENDED FORECAST PERIOD. AS A RESULT...CONFIDENCE IS NEAR
NORMAL THROUGH MONDAY...THEN DROPS BELOW NORMAL TUESDAY THROUGH
FRIDAY.
GUIDANCE HAS COME INTO GOOD AGREEMENT BRINGING A WEAKENING WAVE OF
LOW PRESSURE ACROSS THE NORTHERN GULF COAST STATES SUNDAY AND
TRACKING ACROSS THE GEORGIA/FLORIDA BORDER SUNDAY NIGHT. AS THIS LOW
PASSES BY TO THE SOUTH OF THE FORECAST AREA...A WEDGE OF HIGH
PRESSURE WILL HOLD IN PLACE ACROSS MUCH OF THE EASTERN THIRD OF THE
COUNTRY. THE AREA OF LOW PRESSURE WILL THEN TRACK NORTHEASTWARD OFF
THE EASTERN SEA BOARD AND INTO THE SOUTHERN NEW ENGLAND MONDAY
THROUGH TUESDAY...HELPING TO RE-ENFORCE THE EXISTING HIGH PRESSURE
WEDGE ACROSS THE FORECAST AREA.
MODEL SOLUTIONS THEN REMAIN SPLIT ON DEGREE OF PHASING BETWEEN THE
NORTHERN AND SOUTHERN STREAM WEDNESDAY THROUGH THURSDAY...WITH THE
GFS AND CANADIAN SOLUTIONS SHOWING LITTLE PHASING. AS A
RESULT...THESE MODELS KEEP THE FORECAST AREA UNDER THE INFLUENCE OF
HIGH PRESSURE WITH LITTLE CHANCE FOR RAIN. ON THE OTHER-HAND...THE
ECMWF AND UKMET MODELS DEPICT THE TWO STREAMS PHASING...WHICH
RESULTS IN A WAVE OF LOW PRESSURE TRACKING THROUGH THE SOUTHEAST
STATES ALONG WITH RAIN CHANCES WEDNESDAY THROUGH THURSDAY. GUIDANCE
THEN COMES INTO AGREEMENT BUILDING HIGH PRESSURE INTO THE AREA
THURSDAY NIGHT AND FRIDAY.
AS FOR FORECAST DETAILS...WILL CARRY LIKELY/CATEGORICAL POPS SUNDAY
AND SUNDAY NIGHT AS GOOD FORCING FOR ASCENT ALONG WITH DEEP MOISTURE
AND ISENTROPIC UPGLIDE OVERSPREAD THE FORECAST AREA. MODEL SOLUTIONS
DEPICT SOME DECENT MID-LEVEL LAPSE RATES ON THE ORDER OF 6.5 C/KM
MOVING THROUGH SUNDAY AFTERNOON THROUGH SUNDAY EVENING. ALTHOUGH A
STRONG SURFACE HIGH PRESSURE WEDGE WILL BE IN PLACE...GIVEN THE
DEGREE OF FORCING MOVING OVERHEAD...CAN/T RULE OUT ELEVATED
CONVECTION...SO WILL CARRY THUNDER MENTION IN THE FORECAST AS WELL.
AS SURFACE HIGH PRESSURE WEDGE IS RE-ENFORCED MONDAY THROUGH TUESDAY
AS THE SURFACE AREA OF LOW PRESSURE LIFTS NORTHWARD TOWARD NEW
ENGLAND...NOT ANTICIPATING MUCH IF ANY CLEARING ACROSS THE FORECAST
AREA. MODEL TIME HEIGHT RELATIVE HUMIDITY CROSS SECTIONS INDICATE
THAT THE 1000-850 MB LAYER WILL REMAIN NEARLY SATURATED THROUGH THIS
PERIOD...SO WILL CARRY SLIGHT CHANCE/LOW CHANCE POPS AND MENTION OF
DRIZZLE ACROSS THE FORECAST AREA. HAVE SIGNIFICANTLY UNDERCUT MOS
GUIDANCE MAX TEMPERATURES AS WELL...AS LIGHT WIND FIELDS COMBINED
WITH THE LOW SUN ANGLE SHOULD LEAD TO PRIMARILY OVERCAST CONDITIONS
AND SMALL DIURNAL TEMPERATURE SWINGS.
FORECAST CONFIDENCE GOES DOWNHILL QUICKLY WEDNESDAY AND THURSDAY
WITH GUIDANCE SOLUTIONS SPLIT ON EVENTUAL PATTERN EVOLUTION. FOR NOW
WILL STICK WITH A SOLUTION CLOSE TO THE GFS AND CANADIAN SOLUTIONS
WHICH MAINTAINS GOOD FORECAST CONTINUITY AND AWAIT BETTER MODEL
AGREEMENT BEFORE MAKING ANY SWEEPING CHANGES. THIS RESULTS...IN A
RAIN FREE FORECAST WEDNESDAY THROUGH FRIDAY.
&&
.AVIATION /09Z SATURDAY THROUGH WEDNESDAY/...
KCHS...THE MAIN CONCERN IS THE POTENTIAL FOR MVFR/IFR CIGS LATER
TONIGHT. IFR CIGS HAVE RECENTLY DEVELOPED QUICKLY OVER THE
TRI-COUNTY AREA AND WILL LIKELY EXPAND WITH TIME. WE HAVE RECENTLY
AMENDED THE TAF TO TEMPO IFR CIGS BUT IT LOOKS LIKE ANOTHER
UPDATE IS FORTHCOMING TO MAKE THE STRATUS PREVAILING. GIVEN
RECENT TRENDS...IT MAY BE SLOWER TO REACH VFR LATER THIS MORNING
AND WE WILL RE-EVALUATE ON THE 12Z RELEASE.
KSAV...MVFR VSBYS IN FOG APPEARS POSSIBLE OVERNIGHT AND WE HAVE
MAINTAINED MVFR CONDITIONS AFTER 09Z. WILL CONTINUE TO WATCH
FOR ANY LOW CLOUD FORMATION BUT MODELS INDICATE BEST CHANCES
WILL BE N AND S OF THE TERMINAL. VFR LIKELY FROM MID MORNING
THROUGH THE REMAINDER
EXTENDED AVIATION OUTLOOK...MVFR OR LOWER CIGS AND VSBYS LIKELY
SUNDAY THROUGH TUE. VFR CONDITIONS MAY RETURN ON WED.
&&
.MARINE...
THE PRES GRADIENT WAS PINCHING PRE-DAWN FROM AROUND BUOY 41004 UP
TO THE BUOY 41013. NNE FLOW AVERAGING 10 TO 15 KT OVER OUR WATERS
THIS MORNING...EXCEPT COASTWARD FROM GRAYS REEF WHERE SPEEDS WERE
FAIRLY LIGHT IN A WEAKER GRADIENT. SEAS WERE ELEVATED BEYOND 40
NM OFF THE COAST ACCORDING TO STEADY WAVEWATCH OUTPUT AND FETCH
LENGTH AND PERSISTENCE PROGS. WE WILL CONTINUE WITH MARGINAL
SMALL CRAFT ADVISORY CONDITIONS...MAINLY FOR SEAS OVER OUR OUTER
GEORGIA WATERS. THE COASTAL CAROLINAS PRES GRADIENT WILL TIGHTEN
TONIGHT AND WITH STEADY NE FLOW...IT APPEARS SEAS WILL BUILD INTO
SCA RANGE OFF AT LEAST THE CHARLESTON COUNTY COAST OVERNIGHT. THE
MODELS COULD BE UNDERDONE WITH THE PINCHING AND FORECAST CONDITIONS
MAY TURN OUT SOMEWHAT OPTIMISTIC. OUTER GEORGIA WATERS WILL REMAIN
IN SCA CONDITIONS TONIGHT.
AN AREA OF LOW PRESSURE WILL TRACK EASTWARD ALONG THE NORTHERN GULF
COAST AND GEORGIA/FLORIDA BORDER REGION SUNDAY AND SUNDAY
NIGHT...THEN NORTHEASTWARD ALONG THE EASTERN SEABOARD AND INTO
SOUTHERN NEW ENGLAND MONDAY THROUGH TUESDAY. HIGH PRESSURE WILL THEN
BUILD IN FROM THE WEST ON WEDNESDAY.
EXPECT A FAIRLY STRONG PINCHED GRADIENT ACROSS THE WATERS SUNDAY AND
SUNDAY NIGHT...WITH SMALL CRAFT CONDITIONS CONTINUING ACROSS
PORTIONS OF THE WATERS. AS LOW PRESSURE PULLS AWAY FROM THE REGION
MONDAY...EXPECT IMPROVING CONDITIONS WITH WINDS AND SEAS REMAINING
BELOW SMALL CRAFT THRESHOLDS THROUGH WEDNESDAY.
&&
.TIDES/COASTAL FLOODING...
TIDES AT DOWNTOWN CHARLESTON STILL RUNNING OVER 1 FT ABOVE PREDICTED
LEVELS. WE ARE WATCHING THE HIGH TIDE FOR LATER THIS MORNING...BUT
CURRENT INDICATIONS SUGGEST IT WILL FALL SHY OF COASTAL FLOOD ADVISORY
CRITERIA...BUT NOT BY MUCH.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 5 AM EST MONDAY FOR AMZ374.
SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 5 AM EST
MONDAY FOR AMZ350.
&&
$$
JRJ
000
FXUS62 KGSP 210825
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
325 AM EST SAT NOV 21 2009
.SYNOPSIS...
HIGH PRESSURE WILL REMAIN OVER THE REGION THROUGH MONDAY. A LOW
PRESSURE SYSTEM WILL MOVE EAST ALONG THE GULF COAST THROUGH SUNDAY
THEN NORTH ALONG THE CAROLINA COAST MONDAY. THIS LOW IS EXPECTED TO
REACH THE NEW ENGLAND COAST TUESDAY AS WEAK HIGH PRESSURE REMAINS
OVER THE SOUTHEAST STATES. ANOTHER COLD FRONT OR COASTAL LOW COULD
MOVE INTO THE AREA BY THE MIDDLE OF NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
CURRENT IR SATELLITE IMAGERY INDICATES THAT CIRRUS SHIELD CONTINUES
TO STREAM IN FROM THE SOUTHWEST...AND IS EXPECTED TO CONTINUE
THROUGHOUT THE NEAR TERM PERIOD. MAIN FORECAST PROBLEM THROUGH
TONIGHT CENTERS AROUND THE DEVELOPING WEDGE AND CYCLOGENESIS OVER
THE NORTHERN GULF. CURRENT SUITE OF MODEL RUNS FAVOR MUCH SLOWER
TIMING OF DEEP LAYER MOISTURE SPREADING OVER TOP OF THE COLD DOME. IN
FACT...EVEN THE FASTER GFS SOLUTION SUPPORTS A DRY FORECAST THROUGH
06Z. THEREFORE...I HAVE TRIMMED POPS SIGNIFICANTLY FEATURING ONLY
LOW END CHANCE POPS ACROSS THE SOUTHWESTERN THIRD OF THE
FA...SIMILAR TO THE SREF. AS IT STANDS NOW ONLY THE GFS BRINGS MUCH
IN THE WAY OF ISENTROPIC LIFT INTO THE AREA BY 12Z SO AS IT STANDS
EVEN THIS POP COULD BE A BIT OVERDONE. THE SURFACE HIGH SLIDES INTO
A MORE FAVORABLE WEDGE POSITION THROUGH THE AFTERNOON AND SHOULD BE
WELL IN PLACE BY MID TO LATE MORNING.
I HAVE BLENDED HIGH TEMPS DOWNWARD A BIT TODAY...MORE TOWARD MOS
GUIDANCE. WITH CONSIDERABLE HIGH CLOUDS IN PLACE...SHOULD HELP LIMIT
MAX TEMPS. EXPECT LOW 60S OUTSIDE THE MOUNTAINS...AND UPPER 50S IN
THE MOUNTAIN VALLEYS. LOWS WILL DIP INTO THE LOW TO MID 40S.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 230 AM EST SATURDAY...A SOUTHERN STREAM UPPER LOW WILL MOVE
FROM THE GULF STATES TO THE APPALACHIANS ON SUNDAY AND SUNDAY NIGHT
WHILE WEAKENING. ON MONDAY AND MONDAY NIGHT AND UPPER RIDGE
AMPLIFIES OVER THE SOUTHEAST. THE GFS CONTINUES TO BE FASTER TO
SPREAD MOISTURE AND ISENTROPIC UPGLIDE NORTHEAST ACROSS THE AREA ON
SUNDAY...AND CLOUD COVER AND POPS HAVE BEEN REDUCED TO FAVOR THE
SLOWER NAM/ECMWF SOLUTIONS. POPS HAVE BEEN INCREASED SUNDAY NIGHT
AND MONDAY TO INDICATE A SLOWER EVOLUTION OF COLD AIR DAMMING...
AND A MORE PROLONGED EVENT...WITH LESS OF A DECREASE OF CLOUDS ON
MONDAY NIGHT. SMALL POPS WILL EVEN BE CARRIED ALONG THE BLUE RIDGE
ESCARPMENT MONDAY NIGHT WHERE THE ECMWF INDICATED SOME LINGERING
MOIST UPSLOPE FLOW. MAXIMUM TEMPERATURES HAVE BEEN RAISED A BIT ON
SUNDAY...AND LOWERED ON MONDAY...TO INDICATE THE DELAYED ONSET OF
COLD AIR DAMMING...WITH MINIMUM RAISED SUNDAY NIGHT AND MONDAY
NIGHT. NONE OF THE MODELS HAS NEAR THE AMOUNT OF UPGLIDE OR UPSLOPE
FLOW...SO ONLY MODEST RAINFALL AMOUNTS WIL BE CARRIED...WITH SOME
TERRAIN ENHANCEMENT NEAR THE SOUTH AND SOUTHEAST FACING BLUE RIDGE
ESCARPMENT OF GA AND SC.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 315 AM SATURDAY...HPC CONTINUES TO PREFER THE ECMWF FOR THE
MEDIUM RANGE. THERE ARE DIFFERENCES BETWEEN IT AND THE GFS AND
GEM...WHICH HAVE SIMILAR SOLUTIONS. HOWEVER...THE 00Z ECMWF HAS
TRENDED TOWARD THE GFS AND GEM SOLUTIONS. GIVEN THESE DIFFERENCES
THE EXTENDED FCST REMAINS LOW CONFIDENCE.
THE MODELS AGREE THAT A CLOSED UPPER LOW OVER THE OVER THE PLAINS
MOVES EAST AS A STRONG SHORT WAVE DIVES IN BEHIND THE LOW CREATING
AN EASTERN US TROF. THIS WAVE THEN MERGES WITH OR TAKES THE PLACE OF
THE PREVIOUS LOW AS IT THEN MOVES OFF THE COAST. AT THE SFC...CAD
BEGINS TO ERODE...BUT THERE COULD BE SOME LINGERING PATCHY RAIN TUE
AND TUE NITE. THEN ANOTHER OCCLUDED FNT APPROACHES THE AREA WED AS A
GULF COAST LOW DEVELOPS. THE GFS/GEM KEEP THE FCST DRY AS THE DYING
OCCLUDED FNT HAS LITTLE MOISTURE AND THE COASTAL LOW REMAINS VERY
FAR SOUTH. THE ECMWF HAS MUCH MORE MOISTURE OVER THE AREA AS THE LOW
RIDES ALONG THE COAST. THE ECMWF THEN DRIES THINGS OUT THU AS THE
LOW MOVES UP THE EAST COAST AND AWAY FROM THE AREA. BOTH MDLS SHOW
SOME NW FLOW MOISTURE THU AND FRI. HOWEVER...THE GFS IS MUCH WETTER
AND COLDER SUGGESTING A P-TYPE OF SNOW. GIVEN ALL THIS
UNCERTAINTY...WILL KEEP POPS LIMITED TO SLIGHT CHC. TEMPS START OUT
ABOVE NORMAL THEN COOL BELOW NORMAL. KEPT MTN TEMPS ABOVE FREEZING
DURING THE PERIODS WITH PRECIPITATION...FOR A RAIN P-TYPE.
&&
.AVIATION /09Z SATURDAY THROUGH WEDNESDAY/...
AT KCLT AND ELSEWHERE...HIGH CLOUDS WILL CONTINUE TO STREAM IN
OVERNIGHT AND THROUGH THE DAY...LEAVING ALL SITES WITH AN OVERCAST
CIRRUS LAYER FOR MUCH OF THE TAF PERIOD. THE SURFACE HIGH WILL
SLOWLY MOVE INTO A BETTER COLD AIR DAMMING POSITION THROUGH
TONIGHT...AND WINDS WILL RESPOND ACCORDINGLY GOING NERLY EVERYWHERE
BY MID MORNING. THE LATTER PART OF THE TAF PERIOD DOES PRESENT SOME
CHALLENGES MAINLY BECAUSE OF A CHANGE IN THE TIMING OF LOW CLOUDS
AND PRECIP FAVORED BY THE VARIOUS MODEL SOLUTIONS. EVEN THE FASTEST
MODEL SOLUTION...THE GFS...KEEPS THINGS DRY ACROSS THE CWA THROUGH
06Z AND ALSO KEEPS ANY CEILING RESTRICTIONS TO BEYOND THIS TAF
PERIOD. THEREFORE...WILL KEEP THINGS VFR AT ALL SITES...BUT WILL
BRING IN SOME VFR CIGS IN THE 03-04Z TIME FRAME AT KAND AND
KGSP...MAINLY TO INTRODUCE THE TREND.
OUTLOOK...CLOUD CEILINGS WILL GRADUALLY LOWER SUNDAY MORNING WITH
MVFR CONDITIONS EXPECTED BY LATE MORNING. RAIN WILL DEVELOP OVER THE
REGION ON SUNDAY WITH WIDESPREAD IFR CIGS AND MVFR FOG ARE EXPECTED
TO LAST THROUGH MOST OF MONDAY. FAIR AND DRY WEATHER IS THEN
EXPECTED BY LATE TUESDAY INTO WEDNESDAY.
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...RWH
NEAR TERM...BSH
SHORT TERM...JAT
LONG TERM...RWH
AVIATION...BSH
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