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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
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000
FXUS62 KFFC 212036
AFDFFC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
336 PM EST SAT NOV 21 2009
.SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/...
CURRENT RADAR LOOP SHOWS SOME LIGHT SHOWERS MOVING IN FROM THE SW
WITH MOST OF CENTRAL GA HAVING SEEN 0.01 TO 0.03 INCHES. THIS IS
JUST THE INITIAL PUSH OF MOISTURE FROM THE DEVELOPING LOW PRESSURE
SYSTEM ALONG THE GULF COAST. MODELS ARE SHOWING ANOTHER 1 TO 1.5
INCHES EXPECTED ACROSS THE STATE THROUGH MONDAY MORNING WHICH WILL
NOT BE ENOUGH TO CAUSE ANY MORE FLOODING CONCERNS. THE MODELS SHOW
THE SURFACE LOW ALONG THE LA GULF COAST DEEPENING AS IT TRACKS EAST
TONIGHT...HUGGING THE GULF COAST THROUGH MONDAY MORNING. THIS LOW
WILL BEGIN SLOWLY WEAKENING SUNDAY AS IT MOVES UP THE EAST COAST
THROUGH TUE MORNING. BY THEN IT WILL HAVE PUSHED MOST OF ITS
MOISTURE ACROSS THE REGION AND UP INTO THE MID ATLANTIC STATES. A
WEDGE OF HIGH PRESSURE IS ALSO BEGINNING TO DEEPEN ACROSS THE
EASTERN SEABOARD THIS AFTERNOON AND IT WILL PUSH DOWN INTO N GA
TONIGHT. THIS WEDGE SHOULD KEEP THE ATMOSPHERE OVER THE STATE FAIRLY
STABLE SO NOT EXPECTING ANY THUNDERSTORMS TONIGHT THROUGH MONDAY
MORNING. DEPENDING ON JUST HOW STRONG THIS WEDGE IS WE COULD SEE
LIGHT RAIN OR DRIZZLE CONTINUE THROUGH MONDAY AFTERNOON. WITH THIS
WEDGE BUILDING IN EXPECT TEMPS ACROSS NORTH AND MOST OF CENTRAL GA
TO STAY IN THE 50S ALL DAY SUN AND MOST OF MONDAY. HAVE GONE WELL
BELOW GUIDANCE ESPECIALLY ACROSS CENTRAL GA MON. THIS WEDGE WILL
BEGIN TO ERODE MONDAY SO TEMPS MAY REBOUND SOME...MAINLY ACROSS WEST
AND CENTRAL PORTIONS OF THE FORECAST AREA.
.LONG TERM /TUESDAY THROUGH SATURDAY/...
GFS/ECMWF DIFFER A BIT IN THE EXTENDED PERIODS. GFS STRONGER WITH
THE DEVELOPING LOW OVER THE MIDWEST...BUT FURTHER NORTH THAN THE
ECMWF. ECMWF ALSO SHOWING BETTER MOISTURE RETURN AHEAD OF THE NEXT
SYSTEM TUESDAY AND TUESDAY NIGHT. CANADIAN MODEL IS IN BETTER
AGREEMENT WITH THE GFS AS FAR AS THE POSITIONING OF THE UPPER
LOW...BUT TRENDS TOWARD THE ECMWF SURFACE ANALYSIS WHICH KEEPS THE
WEAK WEDGING AND ATLANTIC MOISTURE ACROSS THE AREA THROUGH TUESDAY.
THE COLD FRONT APPROACHES THE FORECAST AREA BY WEDNESDAY AFTERNOON
AND EXITS THE FORECAST AREA ON THURSDAY WITH BROAD HIGH PRESSURE
BUILDING IN FOR FRIDAY. OVERALL CONFIDENCE IN EXTENDED PERIODS ARE
LOW BUT WILL BLEND THE MODELS HOLDING ONTO CLOUDS AND LOW CHANCE
POPS TUESDAY NIGHT AND WEDNESDAY.
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 46 48 43 53 46 / 40 80 60 30 10
ATLANTA 47 52 44 55 48 / 60 80 40 20 5
BLAIRSVILLE 39 49 45 50 42 / 30 70 50 40 10
CARTERSVILLE 45 53 45 52 46 / 50 80 50 20 5
COLUMBUS 52 58 50 62 49 / 100 80 30 5 10
GAINESVILLE 45 48 42 49 46 / 40 80 50 30 5
MACON 50 56 46 59 46 / 80 90 30 10 10
ROME 43 51 48 57 46 / 50 80 50 20 5
PEACHTREE CITY 47 51 46 59 43 / 70 80 40 20 5
VIDALIA 49 57 46 63 48 / 60 90 50 5 5
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
01
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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 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 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 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 KFFC 211027
AFDFFC
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
520 AM EST SAT NOV 21 2009
.SHORT TERM /TODAY THROUGH MONDAY/...
THE SHORT TERM MODELS ARE IN GOOD GENERAL AGREEMENT ON THE TRACK OF
THE UPPER LOW SWINGING OUT OF TEXAS. GFS IS FASTER LIFTING THE
UPPER LOW THROUGH THE MISSISSIPPI VALLEY SUNDAY...WITH NAM CLOSER
TO THE SLOWER ECMWF. THE SHORT WAVE BECOMES ABSORBED IN THE
LONGWAVE PATTERN ON SUNDAY WHILE THE NEXT SYSTEM DEEPENS AS IT
EXITS THE PACIFIC NORTHWEST...CROSSING THE ROCKIES ON MONDAY. BOTH
THE GFS/NAM DEVELOP A SECONDARY SHORT WAVE OVER THE LOWER OHIO
VALLEY EARLY MONDAY MORNING WHILE ECMWF IS FURTHER NORTH...
ALLOWING STRONGER RIDGING OVER THE SOUTHEAST ON MONDAY.
SURFACE LOW DEVELOPS THIS MORNING ALONG THE EAST TEXAS COAST...AND
THEN TRACKS EAST...HUGGING THE GULF COAST THROUGH MONDAY. AGAIN
NAM/ECMWF IN BETTER AGREEMENT WITH THE SLOWER PROGRESSION OF THE
SURFACE LOW AND BOTH DEPICT STRONGER COLD AIR DAMMING ALONG THE
APPALACHIANS DURING THE DAY ON SUNDAY. THIS WILL KEEP ISOLATED
CONVECTION GENERALLY SOUTH OF A COLUMBUS TO MACON TO AUGUSTA LINE.
BASED UPON THE LATEST NAM/ECMWF SOLUTIONS LIGHT TO MODERATE RAIN
WILL BEGIN LATE TONIGHT/EARLY SUNDAY MORNING AND SPREAD NORTH AND
EAST WITH HEAVIEST RAIN DURING THE DAY ON SUNDAY. GFS/NAM ARE
FURTHER NORTH WHEN DEPICTING THE HEAVIEST RAINFALL... ALONG A
COLUMBUS TO ATHENS LINE WHILE THE ECMWF KEEPS THE HEAVIEST
RAINFALL SOUTH AND EAST OF MACON. NAM/ECMWF NOT AS IMPRESSIVE WITH
RAINFALL DURING THE DAY ON SUNDAY...GENERALLY IN THE 1-2" RANGE
WHICH MATCHES UP WITH THE LATEST HPC QPF GUIDANCE. FLASH FLOOD
GUIDANCE INDICATE 6 HOUR TOTALS OF 3 TO 4.7 INCH TOTALS AND A
FLOOD WATCH IS NOT NECESSARY AT THIS TIME...BUT THERE IS ENOUGH
UNCERTAINTY THAT I WILL CONTINUE SPSFFC.
GUIDANCE TEMPERATURES ARE IN FAIRLY GOOD AGREEMENT...AS HIGH CLOUDS
START TO SPREAD ACROSS THE AREA TODAY TEMPERATURES WILL DROP FROM
MID TO UPPER 60S TO LOWER TO MID 60S. BETTER MOISTURE AND CLOUDS ON
SUNDAY WILL BRING COOLER TEMPERATURES AS MOST AREAS WILL STRUGGLE
INTO THE LOWER 50S. AS WEDGING BEGINS TO ERODE ON MONDAY
TEMPERATURES WILL REBOUND SOME...MAINLY ACROSS WEST AND CENTRAL
PORTIONS OF THE FORECAST AREA...WHERE CLOUDS WILL DIMINISH DURING
THE DAY.
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
GFS/ECMWF CONTINUE THERE DIFFERENCES INTO THE EXTENDED PERIODS OF
THE FORECAST. GFS STRONGER WITH THE DEVELOPING LOW OVER THE
MIDWEST...BUT FURTHER NORTH THE ECMWF. ECMWF ALSO SHOWING BETTER
MOISTURE RETURN AHEAD OF THE NEXT SYSTEM TUESDAY AND TUESDAY
NIGHT. CANADIAN MODEL IS IN BETTER AGREEMENT WITH THE GFS AS FAR
AS THE POSITIONING OF THE UPPER LOW...BUT TRENDS TOWARD THE ECMWF
SURFACE ANALYSIS WHICH KEEPS THE WEAK WEDGING AND ATLANTIC
MOISTURE ACROSS THE AREA THROUGH TUESDAY. THE COLD FRONT
APPROACHES THE FORECAST AREA BY WEDNESDAY AFTERNOON AND EXITS THE
FORECAST AREA ON THURSDAY WITH BROAD HIGH PRESSURE BUILDING IN
FOR FRIDAY. OVERALL CONFIDENCE IN EXTENDED PERIODS ARE LOW BUT WILL
BLEND THE MODELS HOLDING ONTO CLOUDS AND LOW CHANCE POPS TUESDAY
NIGHT AND WEDNESDAY.
&&
.AVIATION...
VFR CEILINGS TODAY...MID/HIGH CLOUDS ASSOCIATED WITH LOW DEVELOPING
VICINITY OF TEXAS COAST. CEILINGS LOWERING BELOW 3 THSD FT AFTER
00Z SUNDAY AND BECOMING IFR AFTER 06Z SUNDAY. RAIN BEGINNING AFTER
00Z AND SPREADING ACROSS GA DURING THE NIGHT AS SURFACE LOW TRACKS
EAST NEAR THE GULF COAST. SOME CONVECTION POSSIBLE MAINLY SOUTH OF
COLUMBUS TO MACON. VISIBILITY TODAY UNRESTRICTED EXCEPT LOCALLY 3 TO
5SM IN FOG UNTIL 14Z. WINDS NORTHEAST INCREASING TO 10 TO 15KT AFTER
14Z.
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 64 46 46 43 57 / 5 70 90 60 40
ATLANTA 64 48 49 44 56 / 5 70 80 50 30
BLAIRSVILLE 60 43 46 43 54 / 0 50 70 40 40
CARTERSVILLE 63 45 50 44 57 / 5 70 80 30 20
COLUMBUS 67 52 57 47 57 / 10 100 90 40 20
GAINESVILLE 63 46 46 44 55 / 5 70 80 40 40
MACON 65 51 56 46 60 / 5 100 100 70 20
ROME 64 46 50 45 57 / 5 70 80 30 20
PEACHTREE CITY 64 47 51 45 56 / 5 80 80 60 20
VIDALIA 66 52 58 47 61 / 0 70 100 60 20
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
12
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 KFFC 210813
AFDFFC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
313 AM EST SAT NOV 21 2009
.SHORT TERM /TODAY THROUGH MONDAY/...
THE SHORT TERM MODELS ARE IN GOOD GENERAL AGREEMENT ON THE TRACK OF
THE UPPER LOW SWINGING OUT OF TEXAS. GFS IS FASTER LIFTING THE
UPPER LOW THROUGH THE MISSISSIPPI VALLEY SUNDAY...WITH NAM CLOSER
TO THE SLOWER ECMWF. THE SHORT WAVE BECOMES ABSORBED IN THE
LONGWAVE PATTERN ON SUNDAY WHILE THE NEXT SYSTEM DEEPENS AS IT
EXITS THE PACIFIC NORTHWEST...CROSSING THE ROCKIES ON MONDAY. BOTH
THE GFS/NAM DEVELOP A SECONDARY SHORT WAVE OVER THE LOWER OHIO
VALLEY EARLY MONDAY MORNING WHILE ECMWF IS FURTHER NORTH...
ALLOWING STRONGER RIDGING OVER THE SOUTHEAST ON MONDAY.
SURFACE LOW DEVELOPS THIS MORNING ALONG THE EAST TEXAS COAST...AND
THEN TRACKS EAST...HUGGING THE GULF COAST THROUGH MONDAY. AGAIN
NAM/ECMWF IN BETTER AGREEMENT WITH THE SLOWER PROGRESSION OF THE
SURFACE LOW AND BOTH DEPICT STRONGER COLD AIR DAMMING ALONG THE
APPALACHIANS DURING THE DAY ON SUNDAY. THIS WILL KEEP ISOLATED
CONVECTION GENERALLY SOUTH OF A COLUMBUS TO MACON TO AUGUSTA LINE.
BASED UPON THE LATEST NAM/ECMWF SOLUTIONS LIGHT TO MODERATE RAIN
WILL BEGIN LATE TONIGHT/EARLY SUNDAY MORNING AND SPREAD NORTH AND
EAST WITH HEAVIEST RAIN DURING THE DAY ON SUNDAY. GFS/NAM ARE
FURTHER NORTH WHEN DEPICTING THE HEAVIEST RAINFALL... ALONG A
COLUMBUS TO ATHENS LINE WHILE THE ECMWF KEEPS THE HEAVIEST
RAINFALL SOUTH AND EAST OF MACON. NAM/ECMWF NOT AS IMPRESSIVE WITH
RAINFALL DURING THE DAY ON SUNDAY...GENERALLY IN THE 1-2" RANGE
WHICH MATCHES UP WITH THE LATEST HPC QPF GUIDANCE. FLASH FLOOD
GUIDANCE INDICATE 6 HOUR TOTALS OF 3 TO 4.7 INCH TOTALS AND A
FLOOD WATCH IS NOT NECESSARY AT THIS TIME...BUT THERE IS ENOUGH
UNCERTAINTY THAT I WILL CONTINUE SPSFFC.
GUIDANCE TEMPERATURES ARE IN FAIRLY GOOD AGREEMENT...AS HIGH CLOUDS
START TO SPREAD ACROSS THE AREA TODAY TEMPERATURES WILL DROP FROM
MID TO UPPER 60S TO LOWER TO MID 60S. BETTER MOISTURE AND CLOUDS ON
SUNDAY WILL BRING COOLER TEMPERATURES AS MOST AREAS WILL STRUGGLE
INTO THE LOWER 50S. AS WEDGING BEGINS TO ERODE ON MONDAY
TEMPERATURES WILL REBOUND SOME...MAINLY ACROSS WEST AND CENTRAL
PORTIONS OF THE FORECAST AREA...WHERE CLOUDS WILL DIMINISH DURING
THE DAY.
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
GFS/ECMWF CONTINUE THERE DIFFERENCES INTO THE EXTENDED PERIODS OF
THE FORECAST. GFS STRONGER WITH THE DEVELOPING LOW OVER THE
MIDWEST...BUT FURTHER NORTH THE ECMWF. ECMWF ALSO SHOWING BETTER
MOISTURE RETURN AHEAD OF THE NEXT SYSTEM TUESDAY AND TUESDAY
NIGHT. CANADIAN MODEL IS IN BETTER AGREEMENT WITH THE GFS AS FAR
AS THE POSITIONING OF THE UPPER LOW...BUT TRENDS TOWARD THE ECMWF
SURFACE ANALYSIS WHICH KEEPS THE WEAK WEDGING AND ATLANTIC
MOISTURE ACROSS THE AREA THROUGH TUESDAY. THE COLD FRONT
APPROACHES THE FORECAST AREA BY WEDNESDAY AFTERNOON AND EXITS THE
FORECAST AREA ON THURSDAY WITH BROAD HIGH PRESSURE BUILDING IN
FOR FRIDAY. OVERALL CONFIDENCE IN EXTENDED PERIODS ARE LOW BUT WILL
BLEND THE MODELS HOLDING ONTO CLOUDS AND LOW CHANCE POPS TUESDAY
NIGHT AND WEDNESDAY.
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 64 46 46 43 57 / 5 70 90 60 40
ATLANTA 64 48 49 44 56 / 5 70 80 50 30
BLAIRSVILLE 60 43 46 43 54 / 0 50 70 40 40
CARTERSVILLE 63 45 50 44 57 / 5 70 80 30 20
COLUMBUS 67 52 57 47 57 / 10 100 90 40 20
GAINESVILLE 63 46 46 44 55 / 5 70 80 40 40
MACON 65 51 56 46 60 / 5 100 100 70 20
ROME 64 46 50 45 57 / 5 70 80 30 20
PEACHTREE CITY 64 47 51 45 56 / 5 80 80 60 20
VIDALIA 66 52 58 47 61 / 0 70 100 60 20
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
12
000
FXUS62 KCHS 210548
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
1248 AM EST SAT NOV 21 2009
.SYNOPSIS...
HIGH PRESSURE WILL BUILD NORTH OF THE REGION THROUGH TONIGHT. A
DEVELOPING GULF LOW PRESSURE SYSTEM WILL MOVE UP THE SOUTHEAST
COAST SATURDAY NIGHT AND SUNDAY. HIGH PRESSURE WILL REBUILD
BEGINNING EARLY NEXT WEEK AND REMAIN THE DOMINANT WEATHER FEATURE
THROUGH MID-WEEK.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
TEMPERATURES HAVE DROPPED QUICKLY THIS EVENING UNDER CLEAR SKIES
AND LIGHT TO CALM WINDS. TEMPERATURES HAVE ALREADY FALLEN INTO
THE UPPER 40S ACROSS THE FAR INLAND COUNTIES PER 21/02Z
OBSERVATIONS WITH 47 RECORDED AT THE NWS SENSOR AT RUFFIN...46 AT
WALTERBORO AND 50 DEGREES AT SYLVANIA. PLAN TO LOWER OVERNIGHT
LOWS BY 2-3 DEGREES ACROSS THE BOARD PER GOING TRENDS. WE DO THINK
TEMPERATURES WILL LEVEL OUT SOME AFTER MIDNIGHT AS HIGH CLOUDS
STREAM IN FROM THE WEST AND LOW STRATUS MOVES ONSHORE FROM OFF THE
ATLANTIC ACROSS THE FAR NORTHERN ZONES. IN FACT A LOCALES ACROSS
THE FAR NORTH AND ALONG THE COAST MAY SEE TEMPERATURES RISE A
DEGREE OR TWO LATE AS THE INCOMING STRATUS HELPS TO INSULATE. WILL
SHOW LOWS FROM THE MID 40S INLAND TO THE MID-UPPER 50S AT THE
COAST.
TRICKY SKY FORECAST FOR TONIGHT. SATELLITE SHOWS HIGH CLOUDS
QUICKLY APPROACHING FROM THE WEST WHILE LOW CLOUDS NOTED OFF THE
NORTHEAST SOUTH CAROLINA COAST MOVE PROGRESSIVELY TOWARD THE LOWER
SOUTH CAROLINA COAST. MODELS HAVE THE LEADING EDGE OF THE LOW STRATUS
DECK REACHING THE CHARLESTON METRO AREA SHORTLY AFTER MIDNIGHT AND
SLOWLY SPREADING WEST AND SOUTH AS THE NIGHT PROGRESSES. ATTM WE
DO NOT BELIEVE THE STRATUS WILL MAKE MUCH IF ANY INROADS INTO
SOUTHEAST GEORGIA...BUT IT WILL BE CLOSE. WILL SHOW MOSTLY CLEAR
SKIES BECOMING PARTLY CLOUDY OVERNIGHT...EXCEPT BECOMING MOSTLY
CLOUDY FOR THE FAR NORTHERN AND COASTAL SOUTH CAROLINA ZONES.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM SUNDAY/...
GUIDANCE HAS REALLY BACKED OFF ON BRINGING THE ISENTROPIC
PRECIPITATION INTO THE REGION ON SATURDAY. THE GFS IS NOW THE
OUTLIER SHOWING SOME LIGHT PRECIP BY AFTERNOON AS MOISTURE SPREADS
OUT AHEAD OF THE DEVELOPING GULF LOW. DUE TO THE AMOUNT OF DRY AIR
TO CONTEND WITH...THE CONSENSUS NAM/ECMWF/GEM/HPC SOLUTION OF
MAINLY DRY CONDITIONS THROUGH SATURDAY SEEMS REASONABLE. WE
RESTRICTED THE SLIGHT CHANCE POPS TO SOUTHEAST GA WHERE THE
SLIGHTLY DEEPER MOISTURE WILL EXIST. ALTHOUGH SOME POCKETS OF SUN
ARE LIKELY...IN GENERAL SKIES WILL BE MOSTLY CLOUDY DURING THE
DAY. HIGHS SHOULD REMAIN IN THE UPPER 60S.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
MEDIUM RANGE GUIDANCE IS STILL IN DISAGREEMENT MUCH OF THE PERIOD
LEADING TO LOWER THAN NORMAL CONFIDENCE.
GUIDANCE SOLUTIONS ARE IN GOOD AGREEMENT DEVELOPING AN AREA OF LOW
PRESSURE ALONG THE NORTHERN GULF COAST SATURDAY NIGHT...BUT THEN
DIFFER SOMEWHAT ON THE EVOLUTION/TRACK OF THE SYSTEM. LATEST
THINKING IS THAT THE INITIAL LOW WILL MOVE INLAND ALONG THE GULF
COAST AND DISSIPATE WHILE THEN TRANSFERRING IT/S ENERGY TO THE SE US
COAST SUN NIGHT. DESPITE THE DISAGREEMENT IN TIMING OF THE SYSTEM
THROUGH THE AREA...THE MODELS ARE IN GENERAL AGREEMENT SHOWING AN
INCREASE IN DEEP MOISTURE...PRESENCE OF SOME UPPER LEVEL
FORCING...AND DECENT ISENTROPIC ASCENT OVERSPREADING THE
AREA...MAINLY EARLY SUN THROUGH SUN NIGHT. HAVE LOWERED POPS A BIT
SAT NIGHT BASED ON THE LATEST SREF AND PREFERRED WRF GUIDANCE. STILL
LOOKS LIKE THE BEST CHANCES OF RAIN WILL COME SUN...WITH DECREASING
CHANCES SUN NIGHT. MON LOOKS RATHER DRY EXCEPT FOR FAR NORTHERN
PORTIONS OF THE FORECAST AREA.
MODEL SOLUTIONS CONTINUE TO DIFFER THROUGH MUCH OF THE UPCOMING WORK
WEEK BUT HAVE GENERALLY FOLLOWED THE DRIER GFS WHICH KEEPS A
SOUTHERN STREAM SYSTEM OFF THE SE US COAST LATE IN THE WEEK.
&&
.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
KCHS...THE MAIN CONCERN IS THE POTENTIAL FOR MVFR/IFR CIGS LATER
TONIGHT. SATELLITE SHOWS A LARGE BATCH OF LOWER CLOUDS OVER
SOUTHEAST NORTH CAROLINA AND ADJACENT WATERS DRIFTING SW. MODELS
SHOW THE LEADING LEDGE OF THE STRATUS DECK MOVING INTO THE KCHS
TERMINAL AFTER 09Z WITH PREVAILING MVFR CIGS. GUIDANCE HAS
BACKED OFF ON THE POTENTIAL FOR OCCASIONAL IFR CIGS AROUND DAWN
BUT WRF SOUNDINGS SUGGEST IT REMAINS POSSIBLE. VFR BY LATE MORNING
OR EARLY AFTERNOON...BUT FORECAST SOUNDINGS INDICATE THAT THE
STRATOCUMULUS COULD REMAIN BROKEN IN THE 3-4 KFT RANGE THROUGH
SAT EVENING.
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
SAT INTO TUE. VFR WED.
&&
.MARINE...
HIGH PRESSURE WILL CONTINUE TO STRENGTHEN NORTH OF THE REGION
OVERNIGHT INTO SATURDAY WITH THE PRESSURE GRADIENT TIGHTENING
ACROSS THE COASTAL WATERS. ALTHOUGH NORTHEAST WINDS ARE EXPECTED
TO REMAIN BELOW 20 KNOTS...SEAS SHOULD BUILD TO 4 TO 6 FT OVER THE
OFFSHORE GA WATERS DURING THE DAY SATURDAY. HAVE HOISTED A SMALL
CRAFT ADVISORY BEGINNING AT 6 AM SATURDAY FOR THESE WATERS.
SATURDAY NIGHT THROUGH WEDNESDAY...AN AREA OF LOW PRESSURE ALONG THE
GULF COAST REGION WILL TRANSFER ITS ENERGY TO A DEVELOPING LOW
PRESSURE SYSTEM OFF THE SE US COAST SUN NIGHT/MON. HIGH PRESSURE
WILL THEN BUILD BACK INTO THE AREA FROM THE WEST THROUGH THE MIDDLE
OF NEXT WEEK.
SMALL CRAFT ADVISORY CONDS ARE POSSIBLE ACROSS PORTIONS OF THE
WATERS SATURDAY NIGHT INTO EARLY SUNDAY WITH IMPROVING CONDITIONS
THEN EXPECTED THROUGH WEDNESDAY AS HIGH PRESSURE TAKES CONTROL.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 6 AM THIS MORNING TO 10 AM EST
SUNDAY FOR AMZ374.
&&
$$
000
FXUS62 KCAE 210528
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
1228 AM EST SAT NOV 21 2009
.SYNOPSIS...
HIGH PRESSURE CENTERED OVER THE LOWER OHIO VALLEY WILL DRIFT EAST
OVER THE NEXT 24 HOURS. SKIES WILL BE CLEAR OVERNIGHT WITH PATCHY
FOG DEVELOPING TOWARD SATURDAY MORNING. A LOW PRESSURE SYSTEM
DEVELOPING OVER THE WESTERN GULF OF MEXICO WILL MOVE NORTHEAST
ACROSS THE FLORIDA PANHANDLE BY SUNDAY NIGHT. THIS SYSTEM WILL
SPREAD RAIN NORTHEAST ACROSS THE AREA LATE SATURDAY NIGHT INTO
MONDAY MORNING. RAINFALL AMOUNTS WILL RANGE FROM A HALF TO THREE
QUARTERS OF AN INCH BEFORE ENDING MONDAY.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
CLEAR SKIES...DRIER AIR...AND LIGHT WINDS HAVE ALLOW EVENING TEMPS
TO FALL A LITTLE FASTER THAT EARLIER FORECAST. HAVE TWEAKED
OVERNIGHT TEMP AND HOURLY GRIDS DOWNWARD ACROSS EASTERN COUNTIES A
LITTLE BIT. ONLY MINOR ADJUSTMENTS MADE TO DEWPOINTS AND WINDS.
HAVE INCREASED CLOUD COVER LATER TONIGHT TO ACCOUNT FOR INCREASE
IN HIGH LEVEL CLOUDINESS FROM THE WEST. UPDATES ALREADY OUT.
PREV DISC...SKIES WILL REMAIN MOSTLY CLEAR THROUGH THE NIGHT AS HIGH
PRESSURE SETTLES OVER THE AREA. RADIATING CONDITIONS WILL BE GOOD
AND TEMPERATURES WILL FALL INTO THE LOWER AND MID 40S 7 AM. PATCHY
DENSE FOG WILL ONCE AGAIN DEVELOP ESPECIALLY IN LOW LYING AREAS
AND AREAS NEAR MOISTURE SOURCES.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY/...
ECMWF/NAM MOVE LOW PRESSURE FROM THE GULF OF MEXICO TO WESTERN
FLORIDA PANHANDLE BY SUNDAY EVENING. THE GFS WAS FASTER IN MOVING
THE SYSTEM. LEANED TO THE SLOWER NAM/ECMWF SOLUTION...SO REMOVED
THE CHANCE OF RAIN SATURDAY...REDUCING POPS SATURDAY NIGHT TO HIGH
CHANCE AND INCREASING THE CHANCE TO 100 PERCENT SUNDAY. HIGH
PRESSURE TO THE NORTH WILL PREVENT ANY WARMER AIR FROM REACHING
THE SURFACE SO EXPECT HIGHS ONLY IN THE 50S SUNDAY.
MODEL GUIDANCE RANGES FROM AROUND A QUARTER OF AN INCH FROM BUFKIT
GRIDS FROM THE NAM TO OVER 1.75 INCHES FROM THE GFS. USED HPC
GUIDANCE FOR THE RAINFALL AMOUNT FORECAST WHICH KEPT AMOUNTS
GENERALLY LESS THAN AN INCH. THERE IS A POTENTIAL FOR HEAVY RAIN
ESPECIALLY IF THE GFS VERIFIES...BUT ALL MODELS GUIDANCE WEAKENS
THE SYSTEM AS IT MOVES NORTHEAST. THEREFORE DID NOT MENTION HEAVY
RAIN IN THE FORECAST AT THIS TIME.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
THE 12Z GFS AND ECMWF RUN SHOW A DIVERGENCE WITH THE GFS FASTER IN
MOVING SYSTEMS THAN THE ECMWF. TEMPERATURES WILL RISE BACK INTO
THE UPPER 60S TO THE LOWER 70S TUESDAY AS A PACIFIC ORIGIN HIGH PRESSURE
MOVES ACROSS THE MID ATLANTIC STATES. A STRONG SYSTEM DEVELOPS
OVER THE MIDWEST TUESDAY AND SWINGS A COLD FRONT THROUGH THE
REGION WEDNESDAY. WITH FORCING WELL TO THE NORTH...IT LOOKS TO BE
A DRY FRONTAL PASSAGE AND THAT IS REFLECTED IN THE FORECAST. THE
FRONT WILL BE FOLLOWED BY A COLD AIR MASS FROM SOUTHERN CANADA.
THIS WILL DROP LOWS INTO THE A COLD AIR MASS FROM CANADA THEN
CROSSES THE MOUNTAINS DROPPING LOW TEMPERATURES INTO THE UPPER 30S
TO LOWER 40S BY FRIDAY MORNING. LEANED TOWARD THE GFS IN THE
EXTENDED FORECAST.
&&
.AVIATION /06Z SATURDAY THROUGH THURSDAY/...
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.
&&
$$
000
FXUS62 KCAE 210425
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
1125 PM EST FRI NOV 20 2009
.SYNOPSIS...
HIGH PRESSURE CENTERED OVER THE LOWER OHIO VALLEY WILL DRIFT EAST
OVER THE NEXT 24 HOURS. SKIES WILL BE CLEAR OVERNIGHT WITH PATCHY
FOG DEVELOPING TOWARD SATURDAY MORNING. A LOW PRESSURE SYSTEM
DEVELOPING OVER THE WESTERN GULF OF MEXICO WILL MOVE NORTHEAST
ACROSS THE FLORIDA PANHANDLE BY SUNDAY NIGHT. THIS SYSTEM WILL
SPREAD RAIN NORTHEAST ACROSS THE AREA LATE SATURDAY NIGHT INTO
MONDAY MORNING. RAINFALL AMOUNTS WILL RANGE FROM A HALF TO THREE
QUARTERS OF AN INCH BEFORE ENDING MONDAY.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
CLEAR SKIES...DRIER AIR...AND LIGHT WINDS HAVE ALLOW EVENING TEMPS
TO FALL A LITTLE FASTER THAT EARLIER FORECAST. HAVE TWEAKED
OVERNIGHT TEMP AND HOURLY GRIDS DOWNWARD ACROSS EASTERN COUNTIES A
LITTLE BIT. ONLY MINOR ADJUSTMENTS MADE TO DEWPOINTS AND WINDS.
HAVE INCREASED CLOUD COVER LATER TONIGHT TO ACCOUNT FOR INCREASE
IN HIGH LEVEL CLOUDINESS FROM THE WEST. UPDATES ALREADY OUT.
PREV DISC...SKIES WILL REMAIN MOSTLY CLEAR THROUGH THE NIGHT AS HIGH
PRESSURE SETTLES OVER THE AREA. RADIATING CONDITIONS WILL BE GOOD
AND TEMPERATURES WILL FALL INTO THE LOWER AND MID 40S 7 AM. PATCHY
DENSE FOG WILL ONCE AGAIN DEVELOP ESPECIALLY IN LOW LYING AREAS
AND AREAS NEAR MOISTURE SOURCES.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY/...
ECMWF/NAM MOVE LOW PRESSURE FROM THE GULF OF MEXICO TO WESTERN
FLORIDA PANHANDLE BY SUNDAY EVENING. THE GFS WAS FASTER IN MOVING
THE SYSTEM. LEANED TO THE SLOWER NAM/ECMWF SOLUTION...SO REMOVED
THE CHANCE OF RAIN SATURDAY...REDUCING POPS SATURDAY NIGHT TO HIGH
CHANCE AND INCREASING THE CHANCE TO 100 PERCENT SUNDAY. HIGH
PRESSURE TO THE NORTH WILL PREVENT ANY WARMER AIR FROM REACHING
THE SURFACE SO EXPECT HIGHS ONLY IN THE 50S SUNDAY.
MODEL GUIDANCE RANGES FROM AROUND A QUARTER OF AN INCH FROM BUFKIT
GRIDS FROM THE NAM TO OVER 1.75 INCHES FROM THE GFS. USED HPC
GUIDANCE FOR THE RAINFALL AMOUNT FORECAST WHICH KEPT AMOUNTS
GENERALLY LESS THAN AN INCH. THERE IS A POTENTIAL FOR HEAVY RAIN
ESPECIALLY IF THE GFS VERIFIES...BUT ALL MODELS GUIDANCE WEAKENS
THE SYSTEM AS IT MOVES NORTHEAST. THEREFORE DID NOT MENTION HEAVY
RAIN IN THE FORECAST AT THIS TIME.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
THE 12Z GFS AND ECMWF RUN SHOW A DIVERGENCE WITH THE GFS FASTER IN
MOVING SYSTEMS THAN THE ECMWF. TEMPERATURES WILL RISE BACK INTO
THE UPPER 60S TO THE LOWER 70S TUESDAY AS A PACIFIC ORIGIN HIGH PRESSURE
MOVES ACROSS THE MID ATLANTIC STATES. A STRONG SYSTEM DEVELOPS
OVER THE MIDWEST TUESDAY AND SWINGS A COLD FRONT THROUGH THE
REGION WEDNESDAY. WITH FORCING WELL TO THE NORTH...IT LOOKS TO BE
A DRY FRONTAL PASSAGE AND THAT IS REFLECTED IN THE FORECAST. THE
FRONT WILL BE FOLLOWED BY A COLD AIR MASS FROM SOUTHERN CANADA.
THIS WILL DROP LOWS INTO THE A COLD AIR MASS FROM CANADA THEN
CROSSES THE MOUNTAINS DROPPING LOW TEMPERATURES INTO THE UPPER 30S
TO LOWER 40S BY FRIDAY MORNING. LEANED TOWARD THE GFS IN THE
EXTENDED FORECAST.
&&
.AVIATION /04Z 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...
NEAR TERM...
SHORT TERM...
LONG TERM...
AVIATION...
000
FXUS62 KCAE 210245
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
945 PM EST FRI NOV 20 2009
.SYNOPSIS...
HIGH PRESSURE CENTERED OVER THE LOWER OHIO VALLEY WILL DRIFT EAST
OVER THE NEXT 24 HOURS. SKIES WILL BE CLEAR OVERNIGHT WITH PATCHY
FOG DEVELOPING TOWARD SATURDAY MORNING. A LOW PRESSURE SYSTEM
DEVELOPING OVER THE WESTERN GULF OF MEXICO WILL MOVE NORTHEAST
ACROSS THE FLORIDA PANHANDLE BY SUNDAY NIGHT. THIS SYSTEM WILL
SPREAD RAIN NORTHEAST ACROSS THE AREA LATE SATURDAY NIGHT INTO
MONDAY MORNING. RAINFALL AMOUNTS WILL RANGE FROM A HALF TO THREE
QUARTERS OF AN INCH BEFORE ENDING MONDAY.
&&
.NEAR TERM /OVERNIGHT/...
CLEAR SKIES...DRIER AIR...AND LIGHT WINDS HAVE ALLOW EVENING TEMPS
TO FALL A LITTLE FASTER THAT EARLIER FORECAST. HAVE TWEAKED
OVERNIGHT TEMP AND HOURLY GRIDS DOWNWARD ACROSS EASTERN COUNTIES A
LITTLE BIT. ONLY MINOR ADJUSTMENTS MADE TO DEWPOINTS AND WINDS.
HAVE INCREASED CLOUD COVER LATER TONIGHT TO ACCOUNT FOR INCREASE
IN HIGH LEVEL CLOUDINESS FROM THE WEST. UPDATES ALREADY OUT.
PREV DISC...SKIES WILL REMAIN MOSTLY CLEAR THROUGH THE NIGHT AS HIGH
PRESSURE SETTLES OVER THE AREA. RADIATING CONDITIONS WILL BE GOOD
AND TEMPERATURES WILL FALL INTO THE LOWER AND MID 40S 7 AM. PATCHY
DENSE FOG WILL ONCE AGAIN DEVELOP ESPECIALLY IN LOW LYING AREAS
AND AREAS NEAR MOISTURE SOURCES.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY/...
ECMWF/NAM MOVE LOW PRESSURE FROM THE GULF OF MEXICO TO WESTERN
FLORIDA PANHANDLE BY SUNDAY EVENING. THE GFS WAS FASTER IN MOVING
THE SYSTEM. LEANED TO THE SLOWER NAM/ECMWF SOLUTION...SO REMOVED
THE CHANCE OF RAIN SATURDAY...REDUCING POPS SATURDAY NIGHT TO HIGH
CHANCE AND INCREASING THE CHANCE TO 100 PERCENT SUNDAY. HIGH
PRESSURE TO THE NORTH WILL PREVENT ANY WARMER AIR FROM REACHING
THE SURFACE SO EXPECT HIGHS ONLY IN THE 50S SUNDAY.
MODEL GUIDANCE RANGES FROM AROUND A QUARTER OF AN INCH FROM BUFKIT
GRIDS FROM THE NAM TO OVER 1.75 INCHES FROM THE GFS. USED HPC
GUIDANCE FOR THE RAINFALL AMOUNT FORECAST WHICH KEPT AMOUNTS
GENERALLY LESS THAN AN INCH. THERE IS A POTENTIAL FOR HEAVY RAIN
ESPECIALLY IF THE GFS VERIFIES...BUT ALL MODELS GUIDANCE WEAKENS
THE SYSTEM AS IT MOVES NORTHEAST. THEREFORE DID NOT MENTION HEAVY
RAIN IN THE FORECAST AT THIS TIME.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
THE 12Z GFS AND ECMWF RUN SHOW A DIVERGENCE WITH THE GFS FASTER IN
MOVING SYSTEMS THAN THE ECMWF. TEMPERATURES WILL RISE BACK INTO
THE UPPER 60S TO THE LOWER 70S TUESDAY AS A PACIFIC ORIGIN HIGH PRESSURE
MOVES ACROSS THE MID ATLANTIC STATES. A STRONG SYSTEM DEVELOPS
OVER THE MIDWEST TUESDAY AND SWINGS A COLD FRONT THROUGH THE
REGION WEDNESDAY. WITH FORCING WELL TO THE NORTH...IT LOOKS TO BE
A DRY FRONTAL PASSAGE AND THAT IS REFLECTED IN THE FORECAST. THE
FRONT WILL BE FOLLOWED BY A COLD AIR MASS FROM SOUTHERN CANADA.
THIS WILL DROP LOWS INTO THE A COLD AIR MASS FROM CANADA THEN
CROSSES THE MOUNTAINS DROPPING LOW TEMPERATURES INTO THE UPPER 30S
TO LOWER 40S BY FRIDAY MORNING. LEANED TOWARD THE GFS IN THE
EXTENDED FORECAST.
&&
.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
FOR CAE...CUB AND DNL ...VFR CONDITIONS EXPECTED THROUGH 10Z. VIS
WILL DETERIORATE TO MVFR IN FOG FROM 10Z-14Z AS GOOD RADIATING
CONDITIONS WILL PREVAIL OVERNIGHT. DEWPOINTS ARE A LITTLE LOWER
TONIGHT THAN THEY WERE LAST NIGHT SO AT THIS TIME EXPECT VIS TO
STAY ABOVE IFR.
AT AGS AND OGB...DEWPOINTS ARE HIGHER SO EXPECT VIS TO GO MVFR
AFTER 06Z TO 08Z WITH TEMPO IFR VIS FROM 10Z TO 13Z. 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 AN APPROACHING LOW PRESSURE SYSTEM.
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.
&&
$$
000
FXUS62 KFFC 210244 AAA
AFDFFC
AREA FORECAST DISCUSSION...UPDATE
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
930 PM EST FRI NOV 20 2009
.UPDATE...
NOT MANY CHANGES NEEDED FOR THE OVERNIGHT PERIOD. INCREASING HIGH
CLOUDS AS INTENSIFYING...VIGOROUS SHORT WAVE LIFTS OUT OF SOUTH TX.
THIS IS A RATHER TYPICAL SYSTEM FOR AN EL NINO TYPE PATTERN.
GFS/ECMWF CONTINUE TO DIFFER ON TIMING...WITH ECMWF HOLDING OFF ON
BRINGING RAIN INTO THE CWA UNTIL LATE SAT. ECMWF HAS GENERALLY BEEN
VERIFYING BETTER RECENTLY. HAVE BACKED OFF ON POPS FOR FIRST THREE
PERIODS AND INCREASED POPS FOR NEXT THREE PERIODS BASED ON SLOWER
ECMWF SOLUTION. QPF STILL IN QUESTION...BUT LATEST HPC GUIDANCE
SUGGESTS 2.0+ INCHES ACROSS CENTRAL PORTIONS OF CWA AND 1.0-1.5
INCHES NORTH. INCREASING CONCERNING FOR AT LEAST MINOR
FLOODING...BUT VALUES REMAIN BELOW 6 HR FFG VALUES OF 3 INCHES NORTH
TO 4.5 INCHES SOUTH. EARLIER SPS HIGHLIGHTS CONCERNS FOR
FLOODING...ESPECIALLY SINCE IT HAS ONLY BEEN A WEEK SINCE THE LAST
FLOOD EVENT. FLOOD WATCH MAY BE NEEDED IF LATER MODEL RUNS CONTINUE
TO SHOW HIGHER QPF FROM SLOWER MOVING/MORE INTENSE SYSTEM. HEAVIEST
RAIN SHOULD FALL SE OF A CSG-MCN-AGS LINE AS MODELS IN GENERAL
AGREEMENT IN TRACKING SFC LOW ACROSS S GA. THERE IS ALSO SOME
CONCERN FOR TSRA IN OUR SOUTHERN ZONES. 18Z GFS AGREES WITH CURRENT
THINKING...HOWEVER...KEEPING TSRA THREAT JUST SOUTH OF THE CWA.
NONETHELESS...SOME TSRA THREAT 00Z-18Z SUN ACROSS OUR SE
COUNTIES...BUT WILL SHOW JUST SE OF CWA FOR NOW. AGAIN...MAIN
CONCERN WILL BE HEAVY RAIN ON SATURATED SOIL.
19
&&
.PREVIOUS FORECAST DISCUSSION ISSUED 525 PM EST FRIDAY...
.SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/...
SURFACE HIGH PRESSURE AND WEAK SOUTHWEST FLOW ALOFT WILL KEEP THE
AREA DRY TONIGHT AND EARLY SATURDAY. STRONG WAVE MOVING OFF THE
SOUTHERN ROCKIES WILL DEVELOP AN ATTENDANT SURFACE LOW ALONG THE
TEXAS GULF COAST...AND LATENT HEAT RELEASE WILL ALLOW THE LOW TO
STRENGTHEN SOMEWHAT OVER THE NEXT DAY OR SO. GFS IS THE FASTEST OF
THE SHORT-TERM MODELS WITH BRINGING THE LOW EAST ALONG THE
COAST...AND ALLOWING MOISTURE TO OVERSPREAD THE SOUTHEAST. HAVE
LEANED MORE TOWARD A COMPROMISE AS THE ECMWF IS THE SLOWEST...AND IS
EVEN SLOWER ON THE LATEST 12Z RUN. IN THE MEANTIME...THE SURFACE
HIGH SLIDES EAST ACROSS THE OHIO VALLEY AND WILL BEGIN RIDGING DOWN
THE EASTERN SLOPES OF THE APPALACHIANS IN A HYBRID DAMMING EVENT
BEGINNING TOMORROW. THIS WILL KEEP TEMPERATURES NOTICEABLY COOLER
SATURDAY AND ESPECIALLY SUNDAY UNDER ALL THE CLOUD COVER...AND WILL
ENHANCE THE AVAILABLE LIFT FOR THE MOISTURE FROM THE COASTAL LOW. DO
NOT EXPECT SIGNIFICANT HEAVY RAINFALL...BUT DO EXPECT WIDESPREAD
LIGHT TO OCCASIONALLY MODERATE RAINFALL BETWEEN LATE SATURDAY AND
SUNDAY...WITH BEST CHANCES SATURDAY NIGHT. OVERALL RAINFALL ANYWHERE
BETWEEN 1-2". THE LOW BEGINS TO FILL IN LATE IN THE SHORT
TERM...UNLESS YOU BELIEVE THE NAM WHICH LINGERS IT NEAR LOUISIANA.
BY THE END OF THE PERIOD THE MOISTURE BEGINS TO MOVE OUT AS THE NEXT
WAVE IN PLAINS KICKS THE COASTAL SYSTEM TOWARD THE NORTHEAST.
.LONG TERM /MONDAY THROUGH FRIDAY/...
AFOREMENTIONED WAVE COMING OFF THE ROCKIES EARLY IN THE WEEK
DEVELOPS INTO A CLOSED LOW OVER THE CENTRAL PLAINS MONDAY INTO
TUESDAY. ATTENDANT FRONT NOT ESPECIALLY IMPRESSIVE...AT LEAST
INITIALLY... DUE TO LACK OF MOISTURE RETURN BEHIND THE WEEKEND
SYSTEM. GFS FASTER...SLIGHTLY DEEPER...AND FURTHER NORTHEAST WITH
THE LOW AND COLD FRONT...BRINGING THE WEAK REMNANTS OF THE FRONT
THROUGH TUESDAY NIGHT...WITH HARDLY MORE THAN AN INCREASE IN CLOUD
COVER INDICATED FOR OUR AREA. ECMWF HAS A VASTLY DIFFERENT
SOLUTION...ALLOWING MORE MOISTURE RETURN WITH THE SLOWER SYSTEM.
IT BRINGS WIDESPREAD MOISTURE TO THE SOUTHEAST DURING THE DAY ON
WEDNESDAY...LINGERING THROUGH EARLY THURSDAY. CONFIDENCE EXTREMELY
LOW TOWARD MIDWEEK. ABOUT THE ONLY THING BOTH MODELS ARE AGREEING
ON IS THE GENERAL TROUGHINESS THAT WILL BE OVER THE EASTERN THIRD
OF THE COUNTRY...BUT EVEN THEN THE GFS INDICATING A MUCH DEEPER
AND COLDER TROUGH. WILL LEAVE THE EXTENDED AS IS FOR NOW WITH ONLY
SLIGHT CHANCE POPS NORTH ON TUESDAY AS THE GFS WOULD INDICATE...
BUT WOULD NOT BE A BIT SURPRISED TO SEE THE ECMWF VERIFY (IT`S
BEEN DOING A MUCH BETTER JOB AT HANDLING THE SYSTEMS COMING
THROUGH LATELY).
25
&&
.AVIATION...
VFR THROUGH THE FORECAST...EXCEPT AFTER 00Z SUN IN ATL WHEN THE RAIN
WILL BECOME MORE WIDESPREAD AND MVFR CIGS WILL ENTER THE AREA.
EXPECT HIGH CLOUDS THROUGH SATURDAY MORNING WITH MID LEVEL MOISTURE
MOVING IN DURING THE LATE MORNING/AFTERNOON. THERE IS A CHANCE OF
RAIN AFTER 21Z IN THE ATL/CSG/MCN AREAS AND WILL ADD A PROB30 TO
THOSE LOCATIONS AFTER 21Z. WINDS WILL REMAIN NORTHEAST LESS THAN 10
KTS THROUGH SATURDAY AFTERNOON.
17
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 43 62 47 52 44 / 0 30 90 90 40
ATLANTA 46 61 48 54 46 / 0 40 90 70 30
BLAIRSVILLE 37 57 43 50 42 / 0 20 80 80 40
CARTERSVILLE 39 60 47 53 45 / 0 30 90 60 30
COLUMBUS 45 60 51 62 47 / 0 50 90 50 20
GAINESVILLE 44 61 46 50 44 / 0 30 90 80 40
MACON 44 64 51 62 46 / 0 40 90 70 20
ROME 39 61 47 56 45 / 0 30 80 60 40
PEACHTREE CITY 39 61 47 56 43 / 0 40 90 60 30
VIDALIA 44 66 53 63 50 / 0 20 90 80 30
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
25/17/19
000
FXUS62 KCHS 210233
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
933 PM EST FRI NOV 20 2009
.SYNOPSIS...
HIGH PRESSURE WILL BUILD NORTH OF THE REGION THROUGH TONIGHT. A
DEVELOPING GULF LOW PRESSURE SYSTEM WILL MOVE UP THE SOUTHEAST
COAST SATURDAY NIGHT AND SUNDAY. HIGH PRESSURE WILL REBUILD
BEGINNING EARLY NEXT WEEK AND REMAIN THE DOMINANT WEATHER FEATURE
THROUGH MID-WEEK.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
TEMPERATURES HAVE DROPPED QUICKLY THIS EVENING UNDER CLEAR SKIES
AND LIGHT TO CALM WINDS. TEMPERATURES HAVE ALREADY FALLEN INTO
THE UPPER 40S ACROSS THE FAR INLAND COUNTIES PER 21/02Z
OBSERVATIONS WITH 47 RECORDED AT THE NWS SENSOR AT RUFFIN...46 AT
WALTERBORO AND 50 DEGREES AT SYLVANIA. PLAN TO LOWER OVERNIGHT
LOWS BY 2-3 DEGREES ACROSS THE BOARD PER GOING TRENDS. WE DO THINK
TEMPERATURES WILL LEVEL OUT SOME AFTER MIDNIGHT AS HIGH CLOUDS
STREAM IN FROM THE WEST AND LOW STRATUS MOVES ONSHORE FROM OFF THE
ATLANTIC ACROSS THE FAR NORTHERN ZONES. IN FACT A LOCALES ACROSS
THE FAR NORTH AND ALONG THE COAST MAY SEE TEMPERATURES RISE A
DEGREE OR TWO LATE AS THE INCOMING STRATUS HELPS TO INSULATE. WILL
SHOW LOWS FROM THE MID 40S INLAND TO THE MID-UPPER 50S AT THE
COAST.
TRICKY SKY FORECAST FOR TONIGHT. SATELLITE SHOWS HIGH CLOUDS
QUICKLY APPROACHING FROM THE WEST WHILE LOW CLOUDS NOTED OFF THE
NORTHEAST SOUTH CAROLINA COAST MOVE PROGRESSIVELY TOWARD THE LOWER
SOUTH CAROLINA COAST. MODELS HAVE THE LEADING EDGE OF THE LOW STRATUS
DECK REACHING THE CHARLESTON METRO AREA SHORTLY AFTER MIDNIGHT AND
SLOWLY SPREADING WEST AND SOUTH AS THE NIGHT PROGRESSES. ATTM WE
DO NOT BELIEVE THE STRATUS WILL MAKE MUCH IF ANY INROADS INTO
SOUTHEAST GEORGIA...BUT IT WILL BE CLOSE. WILL SHOW MOSTLY CLEAR
SKIES BECOMING PARTLY CLOUDY OVERNIGHT...EXCEPT BECOMING MOSTLY
CLOUDY FOR THE FAR NORTHERN AND COASTAL SOUTH CAROLINA ZONES.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/...
GUIDANCE HAS REALLY BACKED OFF ON BRINGING THE ISENTROPIC
PRECIPITATION INTO THE REGION ON SATURDAY. THE GFS IS NOW THE
OUTLIER SHOWING SOME LIGHT PRECIP BY AFTERNOON AS MOISTURE SPREADS
OUT AHEAD OF THE DEVELOPING GULF LOW. DUE TO THE AMOUNT OF DRY AIR
TO CONTEND WITH...THE CONSENSUS NAM/ECMWF/GEM/HPC SOLUTION OF
MAINLY DRY CONDITIONS THROUGH SATURDAY SEEMS REASONABLE. WE
RESTRICTED THE SLIGHT CHANCE POPS TO SOUTHEAST GA WHERE THE
SLIGHTLY DEEPER MOISTURE WILL EXIST. ALTHOUGH SOME POCKETS OF SUN
ARE LIKELY...IN GENERAL SKIES WILL BE MOSTLY CLOUDY DURING THE
DAY. HIGHS SHOULD REMAIN IN THE UPPER 60S.
&&
.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
MEDIUM RANGE GUIDANCE IS STILL IN DISAGREEMENT MUCH OF THE PERIOD
LEADING TO LOWER THAN NORMAL CONFIDENCE.
GUIDANCE SOLUTIONS ARE IN GOOD AGREEMENT DEVELOPING AN AREA OF LOW
PRESSURE ALONG THE NORTHERN GULF COAST SATURDAY NIGHT...BUT THEN
DIFFER SOMEWHAT ON THE EVOLUTION/TRACK OF THE SYSTEM. LATEST
THINKING IS THAT THE INITIAL LOW WILL MOVE INLAND ALONG THE GULF
COAST AND DISSIPATE WHILE THEN TRANSFERRING IT/S ENERGY TO THE SE US
COAST SUN NIGHT. DESPITE THE DISAGREEMENT IN TIMING OF THE SYSTEM
THROUGH THE AREA...THE MODELS ARE IN GENERAL AGREEMENT SHOWING AN
INCREASE IN DEEP MOISTURE...PRESENCE OF SOME UPPER LEVEL
FORCING...AND DECENT ISENTROPIC ASCENT OVERSPREADING THE
AREA...MAINLY EARLY SUN THROUGH SUN NIGHT. HAVE LOWERED POPS A BIT
SAT NIGHT BASED ON THE LATEST SREF AND PREFERRED WRF GUIDANCE. STILL
LOOKS LIKE THE BEST CHANCES OF RAIN WILL COME SUN...WITH DECREASING
CHANCES SUN NIGHT. MON LOOKS RATHER DRY EXCEPT FOR FAR NORTHERN
PORTIONS OF THE FORECAST AREA.
MODEL SOLUTIONS CONTINUE TO DIFFER THROUGH MUCH OF THE UPCOMING WORK
WEEK BUT HAVE GENERALLY FOLLOWED THE DRIER GFS WHICH KEEPS A
SOUTHERN STREAM SYSTEM OFF THE SE US COAST LATE IN THE WEEK.
&&
.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
KCHS...THE MAIN CONCERN IS THE POTENTIAL FOR FOG AND/OR STRATUS.
SATELLITE SHOWS A LARGE BATCH OF STRATUS OVER EASTERN NORTH
CAROLINA MOVING SOUTH. MODELS SHOW THE LEADING LEDGE OF THE
STRATUS DECK MOVING INTO THE KCHS TERMINAL AFTER 07Z WITH
PREVAILING MVFR CEILINGS. GUIDANCE STILL SUGGESTS THERE IS A
POTENTIAL FOR OCCASIONAL CEILINGS AS LOW AS 600-800 FT SO HAVE
INCLUDED A TEMPO GROUP FROM 09-12Z FOR IFR CEILINGS. FOG
PARAMETERS ARE NOT AS FAVORABLE AS THIS MORNING...BUT STILL THINK
THERE WILL ENOUGH PATCHY GROUND FOG AROUND TO REDUCE VISIBILITIES
TO 5SM DESPITE THE 15-20 KT 1000MB GEOSTROPHIC FLOW. LOW CLOUDS
WILL GRADUALLY BURN OFF AFTER 15Z SATURDAY WITH VFR CONDITIONS
RETURNING.
KSAV...CURRENT MODEL TRENDS SUGGEST LOW CLOUDS WILL REMAIN NORTH
OF THE KSAV TERMINAL TONIGHT...BUT IT WILL BE CLOSE. WILL KEEP
CEILINGS OUT OF THE TAF...BUT AVIATION INTERESTS SHOULD BE AWARE
THAT THE STRATUS COULD MAKE A RUN FOR THE TERMINAL LATE TONIGHT.
COULD SEE A LITTLE SHALLOW GROUND FOG DEVELOP AFTER 09Z DESPITE
15-20 KT 1000MB GEOSTROPHIC FLOW WITH VISIBILITIES DROPPING TO
HIGH END MVFR THRESHOLDS. VFR CONDITIONS WILL RETURN AFTER 14Z.
EXTENDED AVIATION OUTLOOK...MVFR OR LOWER CEILINGS AND VSBYS
POSSIBLE SAT THROUGH MON. VFR THEREAFTER.
&&
.MARINE...
HIGH PRESSURE WILL CONTINUE TO STRENGTHEN NORTH OF THE REGION
OVERNIGHT INTO SATURDAY WITH THE PRESSURE GRADIENT TIGHTENING
ACROSS THE COASTAL WATERS. ALTHOUGH NORTHEAST WINDS ARE EXPECTED
TO REMAIN BELOW 20 KNOTS...SEAS SHOULD BUILD TO 4 TO 6 FT OVER THE
OFFSHORE GA WATERS DURING THE DAY SATURDAY. HAVE HOISTED A SMALL
CRAFT ADVISORY BEGINNING AT 6 AM SATURDAY FOR THESE WATERS.
SATURDAY NIGHT THROUGH WEDNESDAY...AN AREA OF LOW PRESSURE ALONG THE
GULF COAST REGION WILL TRANSFER ITS ENERGY TO A DEVELOPING LOW
PRESSURE SYSTEM OFF THE SE US COAST SUN NIGHT/MON. HIGH PRESSURE
WILL THEN BUILD BACK INTO THE AREA FROM THE WEST THROUGH THE MIDDLE
OF NEXT WEEK.
SMALL CRAFT ADVISORY CONDS ARE POSSIBLE ACROSS PORTIONS OF THE
WATERS SATURDAY NIGHT INTO EARLY SUNDAY WITH IMPROVING CONDITIONS
THEN EXPECTED THROUGH WEDNESDAY AS HIGH PRESSURE TAKES CONTROL.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 6 AM SATURDAY TO 10 AM EST SUNDAY
FOR AMZ374.
&&
$$
000
FXUS62 KCAE 210009
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
709 PM EST FRI NOV 20 2009
.SYNOPSIS...
HIGH PRESSURE CENTERED OVER THE LOWER OHIO VALLEY WILL DRIFT EAST
OVER THE NEXT 24 HOURS. SKIES WILL BE CLEAR OVERNIGHT WITH PATCHY
FOG DEVELOPING TOWARD SATURDAY MORNING. A LOW PRESSURE SYSTEM
DEVELOPING OVER THE WESTERN GULF OF MEXICO WILL MOVE NORTHEAST
ACROSS THE FLORIDA PANHANDLE BY SUNDAY NIGHT. THIS SYSTEM WILL
SPREAD RAIN NORTHEAST ACROSS THE AREA LATE SATURDAY NIGHT INTO
MONDAY MORNING. RAINFALL AMOUNTS WILL RANGE FROM A HALF TO THREE
QUARTERS OF AN INCH BEFORE ENDING MONDAY.
&&
.NEAR TERM /UNTIL 7 AM SATURDAY MORNING/...
SKIES WILL REMAIN MOSTLY CLEAR THROUGH THE NIGHT AS HIGH PRESSURE
SETTLES OVER THE AREA. RADIATING CONDITIONS WILL BE GOOD AND TEMPERATURES
WILL FALL INTO THE LOWER AND MID 40S 7 AM. PATCHY DENSE FOG WILL
ONCE AGAIN DEVELOP ESPECIALLY IN LOW LYING AREAS AND AREAS NEAR
MOISTURE SOURCES.
&&
.SHORT TERM /7 AM SATURDAY MORNING THROUGH SUNDAY/...
ECMWF/NAM MOVE LOW PRESSURE FROM THE GULF OF MEXICO TO WESTERN
FLORIDA PANHANDLE BY SUNDAY EVENING. THE GFS WAS FASTER IN MOVING
THE SYSTEM. LEANED TO THE SLOWER NAM/ECMWF SOLUTION...SO REMOVED
THE CHANCE OF RAIN SATURDAY...REDUCING POPS SATURDAY NIGHT TO HIGH
CHANCE AND INCREASING THE CHANCE TO 100 PERCENT SUNDAY. HIGH
PRESSURE TO THE NORTH WILL PREVENT ANY WARMER AIR FROM REACHING
THE SURFACE SO EXPECT HIGHS ONLY IN THE 50S SUNDAY.
MODEL GUIDANCE RANGES FROM AROUND A QUARTER OF AN INCH FROM BUFKIT
GRIDS FROM THE NAM TO OVER 1.75 INCHES FROM THE GFS. USED HPC
GUIDANCE FOR THE RAINFALL AMOUNT FORECAST WHICH KEPT AMOUNTS
GENERALLY LESS THAN AN INCH. THERE IS A POTENTIAL FOR HEAVY RAIN
ESPECIALLY IF THE GFS VERIFIES...BUT ALL MODELS GUIDANCE WEAKENS
THE SYSTEM AS IT MOVES NORTHEAST. THEREFORE DID NOT MENTION HEAVY
RAIN IN THE FORECAST AT THIS TIME.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
THE 12Z GFS AND ECMWF RUN SHOW A DIVERGENCE WITH THE GFS FASTER IN
MOVING SYSTEMS THAN THE ECMWF. TEMPERATURES WILL RISE BACK INTO
THE UPPER 60S TO THE LOWER 70S TUESDAY AS A PACIFIC ORIGIN HIGH PRESSURE
MOVES ACROSS THE MID ATLANTIC STATES. A STRONG SYSTEM DEVELOPS
OVER THE MIDWEST TUESDAY AND SWINGS A COLD FRONT THROUGH THE
REGION WEDNESDAY. WITH FORCING WELL TO THE NORTH...IT LOOKS TO BE
A DRY FRONTAL PASSAGE AND THAT IS REFLECTED IN THE FORECAST. THE
FRONT WILL BE FOLLOWED BY A COLD AIR MASS FROM SOUTHERN CANADA.
THIS WILL DROP LOWS INTO THE A COLD AIR MASS FROM CANADA THEN
CROSSES THE MOUNTAINS DROPPING LOW TEMPERATURES INTO THE UPPER 30S
TO LOWER 40S BY FRIDAY MORNING. LEANED TOWARD THE GFS IN THE
EXTENDED FORECAST.
&&
.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
FOR CAE...CUB AND DNL ...VFR CONDITIONS EXPECTED THRUOGH 10Z. VIS
WILL DETERIORATE TO MVFR IN FOG FROM 10Z-14Z AS GOOD RADIATING
CONDITIONS WILL PREVAIL OVERNIGHT. DEWPOINTS ARE A LITTLE LOWER
TONIGHT THAN THEY WERE LAST NIGHT SO AT THIS TIME EXPECT VIS TO
STAY ABOVE IFR.
AT AGS AND OGB...DEWPOINTS ARE HIGHER SO EXPECT VIS TO GO MVFR
AFTER 06Z TO 08Z WITH TEMPO IFR VIS FROM 10Z TO 13Z. 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 AN APPROACHING LOW PRESSURE SYSTEM.
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...
NEAR TERM...
SHORT TERM...
LONG TERM...
AVIATION...
000
FXUS62 KCHS 202337
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
637 PM EST FRI NOV 20 2009
.SYNOPSIS...
HIGH PRESSURE WILL BUILD NORTH OF THE REGION THROUGH TONIGHT. A
DEVELOPING GULF LOW PRESSURE SYSTEM WILL MOVE UP THE SOUTHEAST
COAST SATURDAY NIGHT AND SUNDAY. HIGH PRESSURE WILL REBUILD
BEGINNING EARLY NEXT WEEK AND REMAIN THE DOMINANT WEATHER FEATURE
THROUGH MID-WEEK.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
HIGH PRESSURE WILL CONTINUE TO RIDGE IN TO THE NORTH TONIGHT...
MAINTAINING A NORTHEAST ONSHORE FLOW OVERNIGHT. THE GRADIENT LOOKS
TO TIGHTEN OVERNIGHT WITH GEOSTROPHIC WINDS INCREASING TO 20-25 KT
BY 12Z SATURDAY. WE SHOULD SEE ANOTHER BATCH OF LOW STRATUS ADVECT
IN FROM THE NORTH OVERNIGHT WHICH WILL PROBABLY AFFECT SIMILAR
PORTIONS OF SOUTHERN SC AS THIS MORNING. FORTUNATELY...FOG DOES
NOT APPEAR TO BE AN ISSUE BECAUSE STRONGER LOW-LEVEL WINDS SHOULD
KEEP THE LOWEST FEW HUNDRED FEET MIXED FAIRLY WELL. LOWS WILL BE
IN THE MIDDLE 40S INLAND WHERE THE WINDS WILL BE LIGHTEST AND SKY
COVER WILL BE MOST LIMITED. ELSEWHERE UPPER 40S TO LOWER 50S
EXPECTED.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/...
GUIDANCE HAS REALLY BACKED OFF ON BRINGING THE ISENTROPIC
PRECIPITATION INTO THE REGION ON SATURDAY. THE GFS IS NOW THE
OUTLIER SHOWING SOME LIGHT PRECIP BY AFTERNOON AS MOISTURE SPREADS
OUT AHEAD OF THE DEVELOPING GULF LOW. DUE TO THE AMOUNT OF DRY AIR
TO CONTEND WITH...THE CONSENSUS NAM/ECMWF/GEM/HPC SOLUTION OF
MAINLY DRY CONDITIONS THROUGH SATURDAY SEEMS REASONABLE. WE
RESTRICTED THE SLIGHT CHANCE POPS TO SOUTHEAST GA WHERE THE
SLIGHTLY DEEPER MOISTURE WILL EXIST. ALTHOUGH SOME POCKETS OF SUN
ARE LIKELY...IN GENERAL SKIES WILL BE MOSTLY CLOUDY DURING THE
DAY. HIGHS SHOULD REMAIN IN THE UPPER 60S.
&&
.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
MEDIUM RANGE GUIDANCE IS STILL IN DISAGREEMENT MUCH OF THE PERIOD
LEADING TO LOWER THAN NORMAL CONFIDENCE.
GUIDANCE SOLUTIONS ARE IN GOOD AGREEMENT DEVELOPING AN AREA OF LOW
PRESSURE ALONG THE NORTHERN GULF COAST SATURDAY NIGHT...BUT THEN
DIFFER SOMEWHAT ON THE EVOLUTION/TRACK OF THE SYSTEM. LATEST
THINKING IS THAT THE INITIAL LOW WILL MOVE INLAND ALONG THE GULF
COAST AND DISSIPATE WHILE THEN TRANSFERRING IT/S ENERGY TO THE SE US
COAST SUN NIGHT. DESPITE THE DISAGREEMENT IN TIMING OF THE SYSTEM
THROUGH THE AREA...THE MODELS ARE IN GENERAL AGREEMENT SHOWING AN
INCREASE IN DEEP MOISTURE...PRESENCE OF SOME UPPER LEVEL
FORCING...AND DECENT ISENTROPIC ASCENT OVERSPREADING THE
AREA...MAINLY EARLY SUN THROUGH SUN NIGHT. HAVE LOWERED POPS A BIT
SAT NIGHT BASED ON THE LATEST SREF AND PREFERRED WRF GUIDANCE. STILL
LOOKS LIKE THE BEST CHANCES OF RAIN WILL COME SUN...WITH DECREASING
CHANCES SUN NIGHT. MON LOOKS RATHER DRY EXCEPT FOR FAR NORTHERN
PORTIONS OF THE FORECAST AREA.
MODEL SOLUTIONS CONTINUE TO DIFFER THROUGH MUCH OF THE UPCOMING WORK
WEEK BUT HAVE GENERALLY FOLLOWED THE DRIER GFS WHICH KEEPS A
SOUTHERN STREAM SYSTEM OFF THE SE US COAST LATE IN THE WEEK.
&&
.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
KCHS...THE MAIN CONCERN IS THE POTENTIAL FOR FOG AND/OR STRATUS.
SATELLITE SHOWS A LARGE BATCH OF STRATUS OVER EASTERN NORTH
CAROLINA MOVING SOUTH. MODELS SHOW THE LEADING LEDGE OF THE
STRATUS DECK MOVING INTO THE KCHS TERMINAL AFTER 07Z WITH
PREVAILING MVFR CEILINGS. GUIDANCE STILL SUGGESTS THERE IS A
POTENTIAL FOR OCCASIONAL CEILINGS AS LOW AS 600-800 FT SO HAVE
INCLUDED A TEMPO GROUP FROM 09-12Z FOR IFR CEILINGS. FOG
PARAMETERS ARE NOT AS FAVORABLE AS THIS MORNING...BUT STILL THINK
THERE WILL ENOUGH PATCHY GROUND FOG AROUND TO REDUCE VISIBILITIES
TO 5SM DESPITE THE 15-20 KT 1000MB GEOSTROPHIC FLOW. LOW CLOUDS
WILL GRADUALLY BURN OFF AFTER 15Z SATURDAY WITH VFR CONDITIONS
RETURNING.
KSAV...CURRENT MODEL TRENDS SUGGEST LOW CLOUDS WILL REMAIN NORTH
OF THE KSAV TERMINAL TONIGHT...BUT IT WILL BE CLOSE. WILL KEEP
CEILINGS OUT OF THE TAF...BUT AVIATION INTERESTS SHOULD BE AWARE
THAT THE STRATUS COULD MAKE A RUN FOR THE TERMINAL LATE TONIGHT.
COULD SEE A LITTLE SHALLOW GROUND FOG DEVELOP AFTER 09Z DESPITE
15-20 KT 1000MB GEOSTROPHIC FLOW WITH VISIBILITIES DROPPING TO
HIGH END MVFR THRESHOLDS. VFR CONDITIONS WILL RETURN AFTER 14Z.
EXTENDED AVIATION OUTLOOK...MVFR OR LOWER CEILINGS AND VSBYS
POSSIBLE SAT THROUGH MON. VFR THEREAFTER.
&&
.MARINE...
HIGH PRESSURE WILL CONTINUE TO STRENGTHEN NORTH OF THE REGION
OVERNIGHT INTO SATURDAY WITH THE PRESSURE GRADIENT TIGHTENING
ACROSS THE COASTAL WATERS. ALTHOUGH NORTHEAST WINDS ARE EXPECTED
TO REMAIN BELOW 20 KNOTS...SEAS SHOULD BUILD TO 4 TO 6 FT OVER THE
OFFSHORE GA WATERS DURING THE DAY SATURDAY. HAVE HOISTED A SMALL
CRAFT ADVISORY BEGINNING AT 6 AM SATURDAY FOR THESE WATERS.
SATURDAY NIGHT THROUGH WEDNESDAY...AN AREA OF LOW PRESSURE ALONG THE
GULF COAST REGION WILL TRANSFER ITS ENERGY TO A DEVELOPING LOW
PRESSURE SYSTEM OFF THE SE US COAST SUN NIGHT/MON. HIGH PRESSURE
WILL THEN BUILD BACK INTO THE AREA FROM THE WEST THROUGH THE MIDDLE
OF NEXT WEEK.
SMALL CRAFT ADVISORY CONDS ARE POSSIBLE ACROSS PORTIONS OF THE
WATERS SATURDAY NIGHT INTO EARLY SUNDAY WITH IMPROVING CONDITIONS
THEN EXPECTED THROUGH WEDNESDAY AS HIGH PRESSURE TAKES CONTROL.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 6 AM SATURDAY TO 10 AM EST SUNDAY
FOR AMZ374.
&&
$$
000
FXUS62 KFFC 202225
AFDFFC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
525 PM EST FRI NOV 20 2009
.SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/...
SURFACE HIGH PRESSURE AND WEAK SOUTHWEST FLOW ALOFT WILL KEEP THE
AREA DRY TONIGHT AND EARLY SATURDAY. STRONG WAVE MOVING OFF THE
SOUTHERN ROCKIES WILL DEVELOP AN ATTENDANT SURFACE LOW ALONG THE
TEXAS GULF COAST...AND LATENT HEAT RELEASE WILL ALLOW THE LOW TO
STRENGTHEN SOMEWHAT OVER THE NEXT DAY OR SO. GFS IS THE FASTEST OF
THE SHORT-TERM MODELS WITH BRINGING THE LOW EAST ALONG THE
COAST...AND ALLOWING MOISTURE TO OVERSPREAD THE SOUTHEAST. HAVE
LEANED MORE TOWARD A COMPROMISE AS THE ECMWF IS THE SLOWEST...AND IS
EVEN SLOWER ON THE LATEST 12Z RUN. IN THE MEANTIME...THE SURFACE
HIGH SLIDES EAST ACROSS THE OHIO VALLEY AND WILL BEGIN RIDGING DOWN
THE EASTERN SLOPES OF THE APPALACHIANS IN A HYBRID DAMMING EVENT
BEGINNING TOMORROW. THIS WILL KEEP TEMPERATURES NOTICEABLY COOLER
SATURDAY AND ESPECIALLY SUNDAY UNDER ALL THE CLOUD COVER...AND WILL
ENHANCE THE AVAILABLE LIFT FOR THE MOISTURE FROM THE COASTAL LOW. DO
NOT EXPECT SIGNIFICANT HEAVY RAINFALL...BUT DO EXPECT WIDESPREAD
LIGHT TO OCCASIONALLY MODERATE RAINFALL BETWEEN LATE SATURDAY AND
SUNDAY...WITH BEST CHANCES SATURDAY NIGHT. OVERALL RAINFALL ANYWHERE
BETWEEN 1-2". THE LOW BEGINS TO FILL IN LATE IN THE SHORT
TERM...UNLESS YOU BELIEVE THE NAM WHICH LINGERS IT NEAR LOUISIANA.
BY THE END OF THE PERIOD THE MOISTURE BEGINS TO MOVE OUT AS THE NEXT
WAVE IN PLAINS KICKS THE COASTAL SYSTEM TOWARD THE NORTHEAST.
.LONG TERM /MONDAY THROUGH FRIDAY/...
AFOREMENTIONED WAVE COMING OFF THE ROCKIES EARLY IN THE WEEK
DEVELOPS INTO A CLOSED LOW OVER THE CENTRAL PLAINS MONDAY INTO
TUESDAY. ATTENDANT FRONT NOT ESPECIALLY IMPRESSIVE...AT LEAST
INITIALLY... DUE TO LACK OF MOISTURE RETURN BEHIND THE WEEKEND
SYSTEM. GFS FASTER...SLIGHTLY DEEPER...AND FURTHER NORTHEAST WITH
THE LOW AND COLD FRONT...BRINGING THE WEAK REMNANTS OF THE FRONT
THROUGH TUESDAY NIGHT...WITH HARDLY MORE THAN AN INCREASE IN CLOUD
COVER INDICATED FOR OUR AREA. ECMWF HAS A VASTLY DIFFERENT
SOLUTION...ALLOWING MORE MOISTURE RETURN WITH THE SLOWER SYSTEM.
IT BRINGS WIDESPREAD MOISTURE TO THE SOUTHEAST DURING THE DAY ON
WEDNESDAY...LINGERING THROUGH EARLY THURSDAY. CONFIDENCE EXTREMELY
LOW TOWARD MIDWEEK. ABOUT THE ONLY THING BOTH MODELS ARE AGREEING
ON IS THE GENERAL TROUGHINESS THAT WILL BE OVER THE EASTERN THIRD
OF THE COUNTRY...BUT EVEN THEN THE GFS INDICATING A MUCH DEEPER
AND COLDER TROUGH. WILL LEAVE THE EXTENDED AS IS FOR NOW WITH ONLY
SLIGHT CHANCE POPS NORTH ON TUESDAY AS THE GFS WOULD INDICATE...
BUT WOULD NOT BE A BIT SURPRISED TO SEE THE ECMWF VERIFY (IT`S
BEEN DOING A MUCH BETTER JOB AT HANDLING THE SYSTEMS COMING
THROUGH LATELY).
TDP
&&
.AVIATION...
VFR THROUGH THE FORECAST...EXCEPT AFTER 00Z SUN IN ATL WHEN THE RAIN
WILL BECOME MORE WIDESPREAD AND MVFR CIGS WILL ENTER THE AREA.
EXPECT HIGH CLOUDS THROUGH SATURDAY MORNING WITH MID LEVEL MOISTURE
MOVING IN DURING THE LATE MORNING/AFTERNOON. THERE IS A CHANCE OF
RAIN AFTER 21Z IN THE ATL/CSG/MCN AREAS AND WILL ADD A PROB30 TO
THOSE LOCATIONS AFTER 21Z. WINDS WILL REMAIN NORTHEAST LESS THAN 10
KTS THROUGH SATURDAY AFTERNOON.
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 43 62 47 52 44 / 0 30 90 90 40
ATLANTA 46 61 48 54 46 / 0 40 90 70 30
BLAIRSVILLE 37 57 43 50 42 / 0 20 80 80 40
CARTERSVILLE 39 60 47 53 45 / 0 30 90 60 30
COLUMBUS 45 60 51 62 47 / 0 50 90 50 20
GAINESVILLE 44 61 46 50 44 / 0 30 90 80 40
MACON 44 64 51 62 46 / 0 40 90 70 20
ROME 39 61 47 56 45 / 0 30 80 60 40
PEACHTREE CITY 39 61 47 56 43 / 0 40 90 60 30
VIDALIA 44 66 53 63 50 / 0 20 90 80 30
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
TDP
000
FXUS62 KCHS 202059
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
359 PM EST FRI NOV 20 2009
.SYNOPSIS...
HIGH PRESSURE WILL BUILD NORTH OF THE REGION THROUGH TONIGHT. A
DEVELOPING GULF LOW PRESSURE SYSTEM WILL MOVE UP THE SOUTHEAST
COAST SATURDAY NIGHT AND SUNDAY. HIGH PRESSURE WILL REBUILD
BEGINNING EARLY NEXT WEEK AND REMAIN THE DOMINANT WEATHER FEATURE
THROUGH MID-WEEK.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
HIGH PRESSURE WILL CONTINUE TO RIDGE IN TO THE NORTH TONIGHT...
MAINTAINING A NORTHEAST ONSHORE FLOW OVERNIGHT. THE GRADIENT LOOKS
TO TIGHTEN OVERNIGHT WITH GEOSTROPHIC WINDS INCREASING TO 20-25 KT
BY 12Z SATURDAY. WE SHOULD SEE ANOTHER BATCH OF LOW STRATUS ADVECT
IN FROM THE NORTH OVERNIGHT WHICH WILL PROBABLY AFFECT SIMILAR
PORTIONS OF SOUTHERN SC AS THIS MORNING. FORTUNATELY...FOG DOES
NOT APPEAR TO BE AN ISSUE BECAUSE STRONGER LOW-LEVEL WINDS SHOULD
KEEP THE LOWEST FEW HUNDRED FEET MIXED FAIRLY WELL. LOWS WILL BE
IN THE MIDDLE 40S INLAND WHERE THE WINDS WILL BE LIGHTEST AND SKY
COVER WILL BE MOST LIMITED. ELSEWHERE UPPER 40S TO LOWER 50S
EXPECTED.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/...
GUIDANCE HAS REALLY BACKED OFF ON BRINGING THE ISENTROPIC
PRECIPITATION INTO THE REGION ON SATURDAY. THE GFS IS NOW THE
OUTLIER SHOWING SOME LIGHT PRECIP BY AFTERNOON AS MOISTURE SPREADS
OUT AHEAD OF THE DEVELOPING GULF LOW. DUE TO THE AMOUNT OF DRY AIR
TO CONTEND WITH...THE CONSENSUS NAM/ECMWF/GEM/HPC SOLUTION OF
MAINLY DRY CONDITIONS THROUGH SATURDAY SEEMS REASONABLE. WE
RESTRICTED THE SLIGHT CHANCE POPS TO SOUTHEAST GA WHERE THE
SLIGHTLY DEEPER MOISTURE WILL EXIST. ALTHOUGH SOME POCKETS OF SUN
ARE LIKELY...IN GENERAL SKIES WILL BE MOSTLY CLOUDY DURING THE
DAY. HIGHS SHOULD REMAIN IN THE UPPER 60S.
&&
.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
MEDIUM RANGE GUIDANCE IS STILL IN DISAGREEMENT MUCH OF THE PERIOD
LEADING TO LOWER THAN NORMAL CONFIDENCE.
GUIDANCE SOLUTIONS ARE IN GOOD AGREEMENT DEVELOPING AN AREA OF LOW
PRESSURE ALONG THE NORTHERN GULF COAST SATURDAY NIGHT...BUT THEN
DIFFER SOMEWHAT ON THE EVOLUTION/TRACK OF THE SYSTEM. LATEST
THINKING IS THAT THE INITIAL LOW WILL MOVE INLAND ALONG THE GULF
COAST AND DISSIPATE WHILE THEN TRANSFERRING IT/S ENERGY TO THE SE US
COAST SUN NIGHT. DESPITE THE DISAGREEMENT IN TIMING OF THE SYSTEM
THROUGH THE AREA...THE MODELS ARE IN GENERAL AGREEMENT SHOWING AN
INCREASE IN DEEP MOISTURE...PRESENCE OF SOME UPPER LEVEL
FORCING...AND DECENT ISENTROPIC ASCENT OVERSPREADING THE
AREA...MAINLY EARLY SUN THROUGH SUN NIGHT. HAVE LOWERED POPS A BIT
SAT NIGHT BASED ON THE LATEST SREF AND PREFERRED WRF GUIDANCE. STILL
LOOKS LIKE THE BEST CHANCES OF RAIN WILL COME SUN...WITH DECREASING
CHANCES SUN NIGHT. MON LOOKS RATHER DRY EXCEPT FOR FAR NORTHERN
PORTIONS OF THE FORECAST AREA.
MODEL SOLUTIONS CONTINUE TO DIFFER THROUGH MUCH OF THE UPCOMING WORK
WEEK BUT HAVE GENERALLY FOLLOWED THE DRIER GFS WHICH KEEPS A
SOUTHERN STREAM SYSTEM OFF THE SE US COAST LATE IN THE WEEK.
&&
.AVIATION /21Z FRIDAY THROUGH WEDNESDAY/...
AT KCHS...LOW CLOUDS FINALLY SHIFTED AWAY FROM THE TERMINAL LATE
THIS MORNING BUT ANOTHER ROUND OF LOW CLOUDS EXPECTED TO MOVE IN
FROM THE NNE LATE THIS EVENING AND OVERNIGHT. WITH HIGH PRESSURE
REMAINING CENTERED TO THE NORTH...20-25 KT NE GEOSTROPHIC WINDS
WILL MAINTAIN A STEADY MOISTURE FEED ABOVE THE INVERSION. ENOUGH
LOW-LEVEL MIXING SHOULD PREVENT THE FORMATION OF MUCH SURFACE FOG.
HOWEVER A PERIOD OF IFR CEILINGS APPEAR INCREASINGLY
LIKELY...MAINLY A FEW HOURS PRIOR TO DAYBREAK SATURDAY. INCLUDED A
TEMPO IFR CEILING FROM 09-12Z. LATER ISSUANCES MAY NEED TO INCLUDE
PREVAILING IFR CEILINGS. PARTIAL CLEARING EXPECTED BY LATE SAT
MORNING ALTHOUGH SOME SCT CLOUDS BELOW 3 KFT MAY PERSIST.
AT KSAV...MOST OF THE LOW CLOUDS TONIGHT ARE EXPECTED ACROSS
SOUTHERN SC BUT THEY COULD EASILY ENCROACH ON THE SAV TERMINAL
OVERNIGHT. WE KEPT VFR CONDITIONS IN THE 18Z TAFS SINCE WE EXPECT
THERE TO BE ENOUGH LOW-LEVEL MIXING TO PRECLUDE FOG FORMATION AND
THE CHANCE FOR STRATUS AT SAV IS TOO LOW AT THIS TIME.
EXTENDED AVIATION OUTLOOK...MVFR OR LOWER CEILINGS AND VSBYS
POSSIBLE SAT THROUGH MON. VFR THEREAFTER.
&&
.MARINE...
HIGH PRESSURE WILL CONTINUE TO STRENGTHEN NORTH OF THE REGION
OVERNIGHT INTO SATURDAY WITH THE PRESSURE GRADIENT TIGHTENING
ACROSS THE COASTAL WATERS. ALTHOUGH NORTHEAST WINDS ARE EXPECTED
TO REMAIN BELOW 20 KNOTS...SEAS SHOULD BUILD TO 4 TO 6 FT OVER THE
OFFSHORE GA WATERS DURING THE DAY SATURDAY. HAVE HOISTED A SMALL
CRAFT ADVISORY BEGINNING AT 6 AM SATURDAY FOR THESE WATERS.
SATURDAY NIGHT THROUGH WEDNESDAY...AN AREA OF LOW PRESSURE ALONG THE
GULF COAST REGION WILL TRANSFER ITS ENERGY TO A DEVELOPING LOW
PRESSURE SYSTEM OFF THE SE US COAST SUN NIGHT/MON. HIGH PRESSURE
WILL THEN BUILD BACK INTO THE AREA FROM THE WEST THROUGH THE MIDDLE
OF NEXT WEEK.
SMALL CRAFT ADVISORY CONDS ARE POSSIBLE ACROSS PORTIONS OF THE
WATERS SATURDAY NIGHT INTO EARLY SUNDAY WITH IMPROVING CONDITIONS
THEN EXPECTED THROUGH WEDNESDAY AS HIGH PRESSURE TAKES CONTROL.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 6 AM SATURDAY TO 10 AM EST SUNDAY
FOR AMZ374.
&&
$$
JRL/RJB
000
FXUS62 KFFC 201956
AFDFFC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
256 PM EST FRI NOV 20 2009
.SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/...
SURFACE HIGH PRESSURE AND WEAK SOUTHWEST FLOW ALOFT WILL KEEP THE
AREA DRY TONIGHT AND EARLY SATURDAY. STRONG WAVE MOVING OFF THE
SOUTHERN ROCKIES WILL DEVELOP AN ATTENDANT SURFACE LOW ALONG THE
TEXAS GULF COAST...AND LATENT HEAT RELEASE WILL ALLOW THE LOW TO
STRENGTHEN SOMEWHAT OVER THE NEXT DAY OR SO. GFS IS THE FASTEST
OF THE SHORT-TERM MODELS WITH BRINGING THE LOW EAST ALONG THE
COAST...AND ALLOWING MOISTURE TO OVERSPREAD THE SOUTHEAST. HAVE
LEANED MORE TOWARD A COMPROMISE AS THE ECMWF IS THE SLOWEST...AND
IS EVEN SLOWER ON THE LATEST 12Z RUN. IN THE MEANTIME...THE
SURFACE HIGH SLIDES EAST ACROSS THE OHIO VALLEY AND WILL BEGIN
RIDGING DOWN THE EASTERN SLOPES OF THE APPALACHIANS IN A HYBRID
DAMMING EVENT BEGINNING TOMORROW. THIS WILL KEEP TEMPERATURES
NOTICEABLY COOLER SATURDAY AND ESPECIALLY SUNDAY UNDER ALL THE
CLOUD COVER...AND WILL ENHANCE THE AVAILABLE LIFT FOR THE MOISTURE
FROM THE COASTAL LOW. DO NOT EXPECT SIGNIFICANT HEAVY RAINFALL...
BUT DO EXPECT WIDESPREAD LIGHT TO OCCASIONALLY MODERATE RAINFALL
BETWEEN LATE SATURDAY AND SUNDAY...WITH BEST CHANCES SATURDAY
NIGHT. OVERALL RAINFALL ANYWHERE BETWEEN 1-2". THE LOW BEGINS TO
FILL IN LATE IN THE SHORT TERM...UNLESS YOU BELIEVE THE NAM WHICH
LINGERS IT NEAR LOUISIANA. BY THE END OF THE PERIOD THE MOISTURE
BEGINS TO MOVE OUT AS THE NEXT WAVE IN PLAINS KICKS THE COASTAL
SYSTEM TOWARD THE NORTHEAST.
.LONG TERM /MONDAY THROUGH FRIDAY/...
AFOREMENTIONED WAVE COMING OFF THE ROCKIES EARLY IN THE WEEK
DEVELOPS INTO A CLOSED LOW OVER THE CENTRAL PLAINS MONDAY INTO
TUESDAY. ATTENDANT FRONT NOT ESPECIALLY IMPRESSIVE...AT LEAST
INITIALLY... DUE TO LACK OF MOISTURE RETURN BEHIND THE WEEKEND
SYSTEM. GFS FASTER...SLIGHTLY DEEPER...AND FURTHER NORTHEAST WITH
THE LOW AND COLD FRONT...BRINGING THE WEAK REMNANTS OF THE FRONT
THROUGH TUESDAY NIGHT...WITH HARDLY MORE THAN AN INCREASE IN CLOUD
COVER INDICATED FOR OUR AREA. ECMWF HAS A VASTLY DIFFERENT
SOLUTION...ALLOWING MORE MOISTURE RETURN WITH THE SLOWER SYSTEM.
IT BRINGS WIDESPREAD MOISTURE TO THE SOUTHEAST DURING THE DAY ON
WEDNESDAY...LINGERING THROUGH EARLY THURSDAY. CONFIDENCE EXTREMELY
LOW TOWARD MIDWEEK. ABOUT THE ONLY THING BOTH MODELS ARE AGREEING
ON IS THE GENERAL TROUGHINESS THAT WILL BE OVER THE EASTERN THIRD
OF THE COUNTRY...BUT EVEN THEN THE GFS INDICATING A MUCH DEEPER
AND COLDER TROUGH. WILL LEAVE THE EXTENDED AS IS FOR NOW WITH ONLY
SLIGHT CHANCE POPS NORTH ON TUESDAY AS THE GFS WOULD INDICATE...
BUT WOULD NOT BE A BIT SURPRISED TO SEE THE ECMWF VERIFY (IT`S
BEEN DOING A MUCH BETTER JOB AT HANDLING THE SYSTEMS COMING
THROUGH LATELY).
TDP
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 43 62 47 52 44 / 0 30 90 90 40
ATLANTA 46 61 48 54 46 / 0 40 90 70 30
BLAIRSVILLE 37 57 43 50 42 / 0 20 80 80 40
CARTERSVILLE 39 60 47 53 45 / 0 30 90 60 30
COLUMBUS 45 60 51 62 47 / 0 50 90 50 20
GAINESVILLE 44 61 46 50 44 / 0 30 90 80 40
MACON 44 64 51 62 46 / 0 40 90 70 20
ROME 39 61 47 56 45 / 0 30 80 60 40
PEACHTREE CITY 39 61 47 56 43 / 0 40 90 60 30
VIDALIA 44 66 53 63 50 / 0 20 90 80 30
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
TDP
000
FXUS62 KCAE 201921
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
221 PM EST FRI NOV 20 2009
.SYNOPSIS...
HIGH PRESSURE CENTERED OVER THE LOWER OHIO VALLEY WILL DRIFT EAST
OVER THE NEXT 24 HOURS. SKIES WILL BE CLEAR OVERNIGHT WITH PATCHY
FOG DEVELOPING TOWARD SATURDAY MORNING. A LOW PRESSURE SYSTEM
DEVELOPING OVER THE WESTERN GULF OF MEXICO WILL MOVE NORTHEAST
ACROSS THE FLORIDA PANHANDLE BY SUNDAY NIGHT. THIS SYSTEM WILL
SPREAD RAIN NORTHEAST ACROSS THE AREA LATE SATURDAY NIGHT INTO
MONDAY MORNING. RAINFALL AMOUNTS WILL RANGE FROM A HALF TO THREE
QUARTERS OF AN INCH BEFORE ENDING MONDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
SKIES WILL REMAIN CLEAR THROUGH THE EARLY EVENING AS HIGH PRESSURE
DOMINATES. TEMPERATURES WILL BE IN THE LOWER 60S BY THAT TIME WITH
LIGHT NORTHEAST WINDS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/...
ECMWF/NAM MOVE LOW PRESSURE FROM THE GULF OF MEXICO TO WESTERN
FLORIDA PANHANDLE BY SUNDAY EVENING. THE GFS WAS FASTER IN MOVING
THE SYSTEM. LEANED TO THE SLOWER NAM/ECMWF SOLUTION...SO REMOVED
THE CHANCE OF RAIN SATURDAY...REDUCING POPS SATURDAY NIGHT TO HIGH
CHANCE AND INCREASING THE CHANCE TO 100 PERCENT SUNDAY. HIGH
PRESSURE TO THE NORTH WILL PREVENT ANY WARMER AIR FROM REACHING
THE SURFACE SO EXPECT HIGHS ONLY IN THE 50S SUNDAY.
MODEL GUIDANCE RANGES FROM AROUND A QUARTER OF AN INCH FROM BUFKIT
GRIDS FROM THE NAM TO OVER 1.75 INCHES FROM THE GFS. USED HPC
GUIDANCE FOR THE RAINFALL AMOUNT FORECAST WHICH KEPT AMOUNTS
GENERALLY LESS THAN AN INCH. THERE IS A POTENTIAL FOR HEAVY RAIN
ESPECIALLY IF THE GFS VERIFIES...BUT ALL MODELS GUIDANCE WEAKENS
THE SYSTEM AS IT MOVES NORTHEAST. THEREFORE DID NOT MENTION HEAVY
RAIN IN THE FORECAST AT THIS TIME.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
THE 12Z GFS AND ECMWF RUN SHOW A DIVERGENCE WITH THE GFS FASTER IN
MOVING SYSTEMS THAN THE ECMWF. TEMPERATURES WILL RISE BACK INTO
THE UPPER 60S TO THE LOWER 70S TUESDAY AS A PACIFIC ORIGIN HIGH PRESSURE
MOVES ACROSS THE MID ATLANTIC STATES. A STRONG SYSTEM DEVELOPS
OVER THE MIDWEST TUESDAY AND SWINGS A COLD FRONT THROUGH THE
REGION WEDNESDAY. WITH FORCING WELL TO THE NORTH...IT LOOKS TO BE
A DRY FRONTAL PASSAGE AND THAT IS REFLECTED IN THE FORECAST. THE
FRONT WILL BE FOLLOWED BY A COLD AIR MASS FROM SOUTHERN CANADA.
THIS WILL DROP LOWS INTO THE A COLD AIR MASS FROM CANADA THEN
CROSSES THE MOUNTAINS DROPPING LOW TEMPERATURES INTO THE UPPER 30S
TO LOWER 40S BY FRIDAY MORNING. LEANED TOWARD THE GFS IN THE
EXTENDED FORECAST.
&&
.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
REMAINING CLOUDS DISSIPATING OVER TAF LOCATIONS THIS AFTERNOON. VFR
CONDITIONS SHOULD CONTINUE THROUGH MOST OF THE REMAINDER OF THE
PERIOD. ANOTHER CHANCE OF FOG EARLY SATURDAY MORNING. EXPECT MVFR
CONDITIONS 10Z-14Z...SOME IFR IS POSSIBLE DURING THIS PERIOD AS WELL.
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...12
NEAR TERM...12
SHORT TERM...12
LONG TERM...12
AVIATION...77
000
FXUS62 KCHS 201750
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
1250 PM EST FRI NOV 20 2009
.SYNOPSIS...
HIGH PRES WILL BUILD N OF THE REGION THROUGH TONIGHT. A GULF LOW
PRES SYSTEM WILL DEVELOP ON SAT THEN MOVE NE ALONG THE SOUTHEAST
COAST SUNDAY AND SUNDAY NIGHT. HIGH PRES WILL THEN BUILD BACK INTO
THE AREA FROM THE W EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
HIGH PRESSURE CONTINUES TO SLOWLY BUILD IN NORTH OF THE REGION
THIS MORNING. A PATCH OF STRATUS THAT ORIGINALLY WAS FAIRLY DENSE
FOG ACROSS SOUTHERN SC CONTINUES TO SLOWLY ERODE ALONG THE EDGES.
SINCE THIS MOISTURE IS TRAPPED BENEATH A NOCTURNAL INVERSION...IT
COULD BE NOON BEFORE THE INVERSION FULLY BURNS OFF AND THIS CLOUD
COVER DISSIPATES. TEMPS HAVE BEEN KEPT DOWN IN AREAS WHERE THIS
STRATUS HAS PERSISTED. WE ADJUSTED TEMPS DOWN 2-3 DEGREES IN THESE
AREAS FOR TODAY. OTHERWISE NO CHANGES PLANNED.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SATURDAY/...
WE MAINTAINED A DRY FORECAST TONIGHT WITH A GRADUALLY INCREASE IN
CLOUDS. HIGH CLOUDS AT FIRST...THEN INCREASES IN STRATOCUMULUS
CLOSER TO THE COAST LATE WITH POTENTIAL FOR MORE INLAND STRATUS
FORMATION LATE. WEAK ISENTROPIC LIFT IS FORECAST TO DEVELOP OFF
THE GEORGIA COAST LATE AND THERE APPEARS TO BE A BOUNDARY LAYER
WARM FRONT TRYING TO DEVELOP TOWARD DAWN ON SAT SOMEWHERE NEAR
JACKSONVILLE OR BRUNSWICK GEORGIA. WE MADE FEW CHANGES TO OUR LOW
TEMPERATURE FORECAST SCHEME WITH 45-49 INLAND AND SOME LOWER 50S
ALONG THE U.S 17 CORRIDOR. NE FLOW WILL KEEP BEACHES MILDER...CLOSER
TO 60 DEGREES FROM EDISTO S TO THE GEORGIA BARRIER ISLANDS.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
MEDIUM RANGE GUIDANCE AGREEMENT LEAVES A LOT TO BE DESIRED THIS
MORNING...WITH THE VARIOUS SOLUTIONS STRUGGLING WITH TIMING AND
POSITION DETAILS OF SYNOPTIC FEATURES THROUGH MOST OF THE EXTENDED
PERIODS. AS A RESULT...FORECAST CONFIDENCE WILL REMAIN LOWER THAN
NORMAL THROUGH THE PERIOD.
GUIDANCE SOLUTIONS ARE IN GOOD AGREEMENT DEVELOPING AN AREA OF LOW
PRESSURE ALONG THE NORTHERN GULF COAST SATURDAY AND SATURDAY
NIGHT...THEN LIFTING THE LOW NORTHEASTWARD ALONG THE GEORGIA AND
SOUTH CAROLINA COAST SUNDAY AND SUNDAY NIGHT. THE EXACT TIMING
DETAILS ARE IN QUESTION HOWEVER...WITH THE NAM AND GFS SOLUTIONS
ROUGHLY 12 HOURS FASTER THAN BOTH THE CANADIAN AND GEM SOLUTIONS.
DESPITE THE DISAGREEMENT IN TIMING OF THE SYSTEM THROUGH THE
AREA...THE MODELS ARE IN GENERAL AGREEMENT SHOWING AN INCREASE IN
DEEP MOISTURE...PRESENCE OF SOME UPPER LEVEL FORCING...AND DECENT
ISENTROPIC ASCENT OVERSPREADING THE AREA LATE SATURDAY AFTERNOON
THROUGH SUNDAY. EXPECT THAT SHOWERS WILL BE SLOW TO DEVELOP
INITIALLY WITH LACK OF DEEP MOISTURE IN PLACE ON SATURDAY...BUT
COULD SEE SOME ISOLATED SHOWERS BY LATE AFTERNOON...SO HAVE INCLUDED
SLIGHT CHANCE POPS TO ACCOUNT FOR THIS. RAIN PROBABILITIES LOOK TO
INCREASE SATURDAY NIGHT AND SUNDAY...AND HAVE CARRIED LIKELY POPS
ACROSS THE ENTIRE FORECAST AREA. AS THE SYSTEM BEGINS PULLING AWAY
FROM THE REGION SUNDAY NIGHT...RAIN PROBABILITIES SHOULD BEGIN TO
DECREASE...SO HAVE KEPT POPS WITHIN THE CHANCE RANGE.
MODEL SOLUTIONS DIFFER SIGNIFICANTLY THROUGH MUCH OF THE UPCOMING
WORK WEEK. THE ECMWF AND CANADIAN MODELS SHOW HIGH PRESSURE WEDGING
BACK INTO THE REGION MONDAY THROUGH TUESDAY...WITH A SOUTHERN STREAM
WAVE THEN LIFTING NORTHEAST OUT OF THE GULF OF MEXICO AND POSSIBLY
IMPACTING THE AREA WEDNESDAY AND THURSDAY. THE GFS ON THE OTHER HAND
BUILDS HIGH PRESSURE BACK INTO THE AREA MONDAY THROUGH THURSDAY AND
KEEPS THE FORECAST AREA RAIN FREE. GIVEN THE HIGH DEGREE OF
UNCERTAINTY THIS FAR OUT...WILL FOLLOW A PERSISTENCE FORECAST AND
KEEP THE THINGS RAIN FREE. FUTURE SHIFTS MAY NEED TO ADD RAIN
CHANCES TO THE FORECAST TUESDAY NIGHT THROUGH THURSDAY IF THE
SOUTHERN STREAM WAVE OF LOW PRESSURE DOES INDEED DEVELOP AND TRACK
NORTHEAST ACROSS THE REGION.
&&
.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
AT KCHS...LOW CLOUDS FINALLY SHIFTED AWAY FROM THE TERMINAL LATE
THIS MORNING BUT ANOTHER ROUND OF LOW CLOUDS EXPECTED TO MOVE IN
FROM THE NNE LATE THIS EVENING AND OVERNIGHT. WITH HIGH PRESSURE
REMAINING CENTERED TO THE NORTH...20-25 KT NE GEOSTROPHIC WINDS
WILL MAINTAIN A STEADY MOISTURE FEED ABOVE THE INVERSION. ENOUGH
LOW-LEVEL MIXING SHOULD PREVENT THE FORMATION OF MUCH SURFACE FOG.
HOWEVER A PERIOD OF IFR CEILINGS APPEAR INCREASINGLY
LIKELY...MAINLY A FEW HOURS PRIOR TO DAYBREAK SATURDAY. INCLUDED A
TEMPO IFR CEILING FROM 09-12Z. LATER ISSUANCES MAY NEED TO INCLUDE
PREVAILING IFR CEILINGS. PARTIAL CLEARING EXPECTED BY LATE SAT
MORNING ALTHOUGH SOME SCT CLOUDS BELOW 3 KFT MAY PERSIST.
AT KSAV...MOST OF THE LOW CLOUDS TONIGHT ARE EXPECTED ACROSS
SOUTHERN SC BUT THEY COULD EASILY ENCROACH ON THE SAV TERMINAL
OVERNIGHT. WE KEPT VFR CONDITIONS IN THE 18Z TAFS SINCE WE EXPECT
THERE TO BE ENOUGH LOW-LEVEL MIXING TO PRECLUDE FOG FORMATION AND
THE CHANCE FOR STRATUS AT SAV IS TOO LOW AT THIS TIME.
EXTENDED AVIATION OUTLOOK...MVFR OR LOWER CEILINGS AND VSBYS
POSSIBLE SAT THROUGH MON. VFR THEREAFTER.
&&
.MARINE...
WINDS WILL VEER TO N AND NE TODAY WITH SPEEDS MOSTLY IN THE 10 TO
15 KT RANGE. THERE IS ALREADY A 2 FT SWELL EVERY 9-11 SECONDS AND
SEAS SHOULD AVERAGE 2-4 FT WITHIN 20 NM TODAY WITH 3-5 FT OVER OUR
GEORGIA WATERS BEYOND 20 NM...HIGHEST SEAS BEYOND 40 NM. WE SHOULD
SEE A BIT OF PINCHING GRADIENT LATER TODAY AS TEMPERATURE AND
MOISTURE GRADIENTS TIGHTEN. OVERALL WE SHOULD SEE NE FLOW 15 KT
WITH SEAS 3-5 FT.
SATURDAY THROUGH TUESDAY...AN AREA OF LOW PRESSURE WILL DEVELOP
ACROSS THE NORTHERN GULF COAST OVER THE WEEKEND...WHILE SURFACE HIGH
PRESSURE TO THE NORTH MAINTAINS AN INLAND WEDGE. THIS AREA OF LOW
PRESSURE WILL LIFT NORTHEAST AND LIKELY PROGRESS ALONG THE
GEORGIA/SOUTH CAROLINA COASTLINE SUNDAY AND SUNDAY NIGHT. HIGH
PRESSURE WILL THEN BUILD BACK INTO THE AREA NEXT WEEK.
WINDS AND/OR SEAS COULD APPROACH SMALL CRAFT LEVELS ACROSS PORTIONS
OF THE WATERS SATURDAY THROUGH SUNDAY AS THE AREA OF LOW PRESSURE
ALLOWS THE GRADIENT TO PINCH FAIRLY WELL AS IT APPROACHES THE
REGION. IMPROVING CONDITIONS ARE THEN ANTICIPATED SUNDAY NIGHT
THROUGH TUESDAY...WITH WINDS AND SEAS REMAINING BELOW SMALL CRAFT
THRESHOLDS.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.
&&
$$
JRL
000
FXUS62 KCAE 201741
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
1241 PM EST FRI NOV 20 2009
.SYNOPSIS...
HIGH PRESSURE WILL COVER THE AREA THIS AFTERNOON. LOW PRESSURE IN THE
GULF OF MEXICO WILL SPREAD CLOUDS AND A CHANCE OF RAIN BY LATE
SATURDAY. THE LOW WILL MOVE NORTHEAST SATURDAY NIGHT AND SUNDAY
WITH RAIN EXPECTED OVER THE REGION. THE LOW WILL BEGIN TO MOVE
AWAY SUNDAY NIGHT.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
HIGH PRESSURE WILL COVER THE REGION. SOME LOW LEVEL MOISTURE THIS
MORNING WILL ALLOW SOME PATCHY DENSE FOG TO DEVELOP NEAR RIVERS
AND STREAMS BUT WIDESPREAD DENSE FOG IS NOT EXPECTED, HIGHS THIS
AFTERNOON WILL BE IN THE UPPER 60S TO LOWER 70S.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/...
HIGH PRESSURE OVER THE AREA WILL WEAKEN OVERNIGHT. A DEVELOPING
LOW PRESSURE AREA IN THE NORTHERN GULF OF MEXICO WILL SPREAD
CLOUDS AND A CHANCE OF RAIN TO THE REGION BY LATE IN THE DAY ON
SATURDAY. SATURDAY WILL BE COOLER WITH HIGH TEMPERATURES IN THE
LOWER TO MIDDLE 60S. A 70-80 PERCENT CHANCE OF RAIN IS EXPECTED
SATURDAY NIGHT AND SUNDAY AS THE LOW MOVES NORTHEAST OFF THE SOUTH
CAROLINA COAST. NOT MUCH CHANGE IN TEMPERATURES SATURDAY NIGHT
WITH LOWS IN THE UPPER 40S TO LOWER 50S. SUNDAY HIGHS ARE IN THE
50S. QPF VALUES ARE UP TO AROUND ONE INCH BY SUNDAY.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
IN GOOD AGREEMENT WITH LONG RANGE MODELS. AFTER SYSTEM MOVES AWAY
SUNDAY NIGHT...ZONAL FLOW WITH SURFACE HIGH PRESSURE MONDAY GIVE
WAY TO UPPER SOUTHWEST FLOW TUESDAY AS A DRY COLD FRONT APPROACHES
TUESDAY NIGHT. HIGH PRESSURE MOVES IN FOR WEDNESDAY AND
THANKSGIVING DAY. TEMPERATURES START OFF A FEW DEGREES ABOVE
NORMAL WITH HIGHS UP NEAR 70 MONDAY AND TUESDAY WITH LOWS IN THE
40S. COOLER CONDITIONS EXPECTED BY WEDNESDAY AND THANKSGIVING DAY
WITH HIGHS CLOSER TO 60 AND LOWS IN THE UPPER 30S TO LOWER 40S.
&&
.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
REMAINING CLOUDS DISSIPATING OVER TAF LOCATIONS THIS AFTERNOON. VFR
CONDITIONS SHOULD CONTINUE THROUGH MOST OF THE REMAINDER OF THE
PERIOD. ANOTHER CHANCE OF FOG EARLY SATURDAY MORNING. EXPECT MVFR
CONDITIONS 10Z-14Z...SOME IFR IS POSSIBLE DURING THIS PERIOD AS WELL.
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.
&&
$$
000
FXUS62 KCHS 201537
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
1037 AM EST FRI NOV 20 2009
.SYNOPSIS...
HIGH PRES WILL BUILD N OF THE REGION THROUGH TONIGHT. A GULF LOW
PRES SYSTEM WILL DEVELOP ON SAT THEN MOVE NE ALONG THE SOUTHEAST
COAST SUNDAY AND SUNDAY NIGHT. HIGH PRES WILL THEN BUILD BACK INTO
THE AREA FROM THE W EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
HIGH PRESSURE CONTINUES TO SLOWLY BUILD IN NORTH OF THE REGION
THIS MORNING. A PATCH OF STRATUS THAT ORIGINALLY WAS FAIRLY DENSE
FOG ACROSS SOUTHERN SC CONTINUES TO SLOWLY ERODE ALONG THE EDGES.
SINCE THIS MOISTURE IS TRAPPED BENEATH A NOCTURNAL INVERSION...IT
COULD BE NOON BEFORE THE INVERSION FULLY BURNS OFF AND THIS CLOUD
COVER DISSIPATES. TEMPS HAVE BEEN KEPT DOWN IN AREAS WHERE THIS
STRATUS HAS PERSISTED. WE ADJUSTED TEMPS DOWN 2-3 DEGREES IN THESE
AREAS FOR TODAY. OTHERWISE NO CHANGES PLANNED.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SATURDAY/...
WE MAINTAINED A DRY FORECAST TONIGHT WITH A GRADUALLY INCREASE IN
CLOUDS. HIGH CLOUDS AT FIRST...THEN INCREASES IN STRATOCUMULUS
CLOSER TO THE COAST LATE WITH POTENTIAL FOR MORE INLAND STRATUS
FORMATION LATE. WEAK ISENTROPIC LIFT IS FORECAST TO DEVELOP OFF
THE GEORGIA COAST LATE AND THERE APPEARS TO BE A BOUNDARY LAYER
WARM FRONT TRYING TO DEVELOP TOWARD DAWN ON SAT SOMEWHERE NEAR
JACKSONVILLE OR BRUNSWICK GEORGIA. WE MADE FEW CHANGES TO OUR LOW
TEMPERATURE FORECAST SCHEME WITH 45-49 INLAND AND SOME LOWER 50S
ALONG THE U.S 17 CORRIDOR. NE FLOW WILL KEEP BEACHES MILDER...CLOSER
TO 60 DEGREES FROM EDISTO S TO THE GEORGIA BARRIER ISLANDS.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
MEDIUM RANGE GUIDANCE AGREEMENT LEAVES A LOT TO BE DESIRED THIS
MORNING...WITH THE VARIOUS SOLUTIONS STRUGGLING WITH TIMING AND
POSITION DETAILS OF SYNOPTIC FEATURES THROUGH MOST OF THE EXTENDED
PERIODS. AS A RESULT...FORECAST CONFIDENCE WILL REMAIN LOWER THAN
NORMAL THROUGH THE PERIOD.
GUIDANCE SOLUTIONS ARE IN GOOD AGREEMENT DEVELOPING AN AREA OF LOW
PRESSURE ALONG THE NORTHERN GULF COAST SATURDAY AND SATURDAY
NIGHT...THEN LIFTING THE LOW NORTHEASTWARD ALONG THE GEORGIA AND
SOUTH CAROLINA COAST SUNDAY AND SUNDAY NIGHT. THE EXACT TIMING
DETAILS ARE IN QUESTION HOWEVER...WITH THE NAM AND GFS SOLUTIONS
ROUGHLY 12 HOURS FASTER THAN BOTH THE CANADIAN AND GEM SOLUTIONS.
DESPITE THE DISAGREEMENT IN TIMING OF THE SYSTEM THROUGH THE
AREA...THE MODELS ARE IN GENERAL AGREEMENT SHOWING AN INCREASE IN
DEEP MOISTURE...PRESENCE OF SOME UPPER LEVEL FORCING...AND DECENT
ISENTROPIC ASCENT OVERSPREADING THE AREA LATE SATURDAY AFTERNOON
THROUGH SUNDAY. EXPECT THAT SHOWERS WILL BE SLOW TO DEVELOP
INITIALLY WITH LACK OF DEEP MOISTURE IN PLACE ON SATURDAY...BUT
COULD SEE SOME ISOLATED SHOWERS BY LATE AFTERNOON...SO HAVE INCLUDED
SLIGHT CHANCE POPS TO ACCOUNT FOR THIS. RAIN PROBABILITIES LOOK TO
INCREASE SATURDAY NIGHT AND SUNDAY...AND HAVE CARRIED LIKELY POPS
ACROSS THE ENTIRE FORECAST AREA. AS THE SYSTEM BEGINS PULLING AWAY
FROM THE REGION SUNDAY NIGHT...RAIN PROBABILITIES SHOULD BEGIN TO
DECREASE...SO HAVE KEPT POPS WITHIN THE CHANCE RANGE.
MODEL SOLUTIONS DIFFER SIGNIFICANTLY THROUGH MUCH OF THE UPCOMING
WORK WEEK. THE ECMWF AND CANADIAN MODELS SHOW HIGH PRESSURE WEDGING
BACK INTO THE REGION MONDAY THROUGH TUESDAY...WITH A SOUTHERN STREAM
WAVE THEN LIFTING NORTHEAST OUT OF THE GULF OF MEXICO AND POSSIBLY
IMPACTING THE AREA WEDNESDAY AND THURSDAY. THE GFS ON THE OTHER HAND
BUILDS HIGH PRESSURE BACK INTO THE AREA MONDAY THROUGH THURSDAY AND
KEEPS THE FORECAST AREA RAIN FREE. GIVEN THE HIGH DEGREE OF
UNCERTAINTY THIS FAR OUT...WILL FOLLOW A PERSISTENCE FORECAST AND
KEEP THE THINGS RAIN FREE. FUTURE SHIFTS MAY NEED TO ADD RAIN
CHANCES TO THE FORECAST TUESDAY NIGHT THROUGH THURSDAY IF THE
SOUTHERN STREAM WAVE OF LOW PRESSURE DOES INDEED DEVELOP AND TRACK
NORTHEAST ACROSS THE REGION.
&&
.AVIATION /16Z FRIDAY THROUGH TUESDAY/...
AT KCHS...SFC VSBY HAD IMPROVED TO NEAR 1SM AS WINDS HAVE PICKED
UP RECENTLY AND RUC 1000 MB GEOSTROPHIC FLOW WAS CLOSE TO 20 KT AT
11Z. THE STRATUS DECK STILL COULD BE A BIT SLOW TO LIFT AND
DISSIPATE THIS MORNING AND WE SHOWED LOW CLOUDS/IFR ENDING AROUND
1530Z. VFR IS ANTICIPATED THIS AFTERNOON AND EVENING. MVFR OR IFR
MAY RETURN AFTER 08Z/21 AS GFS/SREF MODELS SUGGEST. WE HAVE
INTRODUCED SOME LATE NIGHT MVFR AT THIS POINT.
AT KSAV...EXPANSIVE AREA OF STRATUS AND FOG IN SOUTH CAROLINA IS
STILL PLOWING SOUTH AT DAWN THIS MORNING. STRATUS AND/OR FOG
STILL COULD REACH THE TERMINAL BETWEEN 13Z-14Z BUT BY THAT TIME IT
LOOKS LIKE SURFACE DEW POINT DEPRESSIONS WILL BE ON A STEADY
INCLINE. THE REMAINDER OF THE 12Z TAF CYCLE LOOKS VFR AND WILL
NEED TO MONITOR FOR SOME VERY LATE NIGHT LOW CLOUDS EARLY SAT.
EXTENDED AVIATION OUTLOOK...MVFR OR LOWER CEILINGS AND VSBYS
POSSIBLE SAT THROUGH MON. VFR THEREAFTER.
&&
.MARINE...
WINDS WILL VEER TO N AND NE TODAY WITH SPEEDS MOSTLY IN THE 10 TO
15 KT RANGE. THERE IS ALREADY A 2 FT SWELL EVERY 9-11 SECONDS AND
SEAS SHOULD AVERAGE 2-4 FT WITHIN 20 NM TODAY WITH 3-5 FT OVER OUR
GEORGIA WATERS BEYOND 20 NM...HIGHEST SEAS BEYOND 40 NM. WE SHOULD
SEE A BIT OF PINCHING GRADIENT LATER TODAY AS TEMPERATURE AND
MOISTURE GRADIENTS TIGHTEN. OVERALL WE SHOULD SEE NE FLOW 15 KT
WITH SEAS 3-5 FT.
SATURDAY THROUGH TUESDAY...AN AREA OF LOW PRESSURE WILL DEVELOP
ACROSS THE NORTHERN GULF COAST OVER THE WEEKEND...WHILE SURFACE HIGH
PRESSURE TO THE NORTH MAINTAINS AN INLAND WEDGE. THIS AREA OF LOW
PRESSURE WILL LIFT NORTHEAST AND LIKELY PROGRESS ALONG THE
GEORGIA/SOUTH CAROLINA COASTLINE SUNDAY AND SUNDAY NIGHT. HIGH
PRESSURE WILL THEN BUILD BACK INTO THE AREA NEXT WEEK.
WINDS AND/OR SEAS COULD APPROACH SMALL CRAFT LEVELS ACROSS PORTIONS
OF THE WATERS SATURDAY THROUGH SUNDAY AS THE AREA OF LOW PRESSURE
ALLOWS THE GRADIENT TO PINCH FAIRLY WELL AS IT APPROACHES THE
REGION. IMPROVING CONDITIONS ARE THEN ANTICIPATED SUNDAY NIGHT
THROUGH TUESDAY...WITH WINDS AND SEAS REMAINING BELOW SMALL CRAFT
THRESHOLDS.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.
&&
$$
JRL
000
FXUS62 KCHS 201200
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
700 AM EST FRI NOV 20 2009
.SYNOPSIS...
HIGH PRES WILL BUILD N OF THE REGION THROUGH TONIGHT. A GULF LOW
PRES SYSTEM WILL DEVELOP ON SAT THEN MOVE NE ALONG THE SOUTHEAST
COAST SUNDAY AND SUNDAY NIGHT. HIGH PRES WILL THEN BUILD BACK INTO
THE AREA FROM THE W EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
SATELLITE IMAGERY INDICATES LOW CLOUDS/STRATUS SINKING S TO THE E
OF I-95 AND TO THE NORTH OF SAVANNAH THIS MORNING. VSBYS WERE
DOWN TO 1/4 MILE OR LESS AT TIMES OVER THIS REGION. WE MAINTAINED THE
DENSE FOG ADVISORY FOR OUR 4 NORTHERN SOUTH CAROLINA ZONES AND
ADDED COASTAL COLLETON AND BEAUFORT COUNTIES RECENTLY. AREAS OF
FOG MAY DEVELOP OVER THE REMAINDER OF OUR SOUTHERN FORECAST AREA
TOWARD DAWN...BUT WIDESPREAD DENSE FOG SEEMS UNLIKELY IN SOUTHEAST
GEORGIA GIVEN THE LATEST TRENDS.
AFTER THE FOG DISSIPATES AFTER MID MORNING...SOME AREAS OF
STRATUS MAY TAKE ANOTHER HOUR OR TWO TO BURN OFF IN PLACES LIKE
JAMESTOWN AND AROUND LAKE MOULTRIE. OTHERWISE...WE THINK OUR
REGION WILL SEE MOSTLY SUNNY SKIES WITH A WEAK COLD AIR ADVECTION
PATTERN. HIGH PRES BUILDING TO OUR NW AND N WILL KEEP AFTERNOON
TEMPERATURES CLOSER TO 70 WITH HIGHS MANY AREAS IN THE LOWER 70S.
BEACHES WILL SHARE IN THE SUNSHINE THIS AFTERNOON...BUT READINGS
WILL ONLY BE IN THE LOWER TO MID 60S WITH NE BREEZES KICKING IN.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SATURDAY/...
WE MAINTAINED A DRY FORECAST TONIGHT WITH A GRADUALLY INCREASE IN
CLOUDS. HIGH CLOUDS AT FIRST...THEN INCREASES IN STRATOCUMULUS
CLOSER TO THE COAST LATE WITH POTENTIAL FOR MORE INLAND STRATUS
FORMATION LATE. WEAK ISENTROPIC LIFT IS FORECAST TO DEVELOP OFF
THE GEORGIA COAST LATE AND THERE APPEARS TO BE A BOUNDARY LAYER
WARM FRONT TRYING TO DEVELOP TOWARD DAWN ON SAT SOMEWHERE NEAR
JACKSONVILLE OR BRUNSWICK GEORGIA. WE MADE FEW CHANGES TO OUR LOW
TEMPERATURE FORECAST SCHEME WITH 45-49 INLAND AND SOME LOWER 50S
ALONG THE U.S 17 CORRIDOR. NE FLOW WILL KEEP BEACHES MILDER...CLOSER
TO 60 DEGREES FROM EDISTO S TO THE GEORGIA BARRIER ISLANDS.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
MEDIUM RANGE GUIDANCE AGREEMENT LEAVES A LOT TO BE DESIRED THIS
MORNING...WITH THE VARIOUS SOLUTIONS STRUGGLING WITH TIMING AND
POSITION DETAILS OF SYNOPTIC FEATURES THROUGH MOST OF THE EXTENDED
PERIODS. AS A RESULT...FORECAST CONFIDENCE WILL REMAIN LOWER THAN
NORMAL THROUGH THE PERIOD.
GUIDANCE SOLUTIONS ARE IN GOOD AGREEMENT DEVELOPING AN AREA OF LOW
PRESSURE ALONG THE NORTHERN GULF COAST SATURDAY AND SATURDAY
NIGHT...THEN LIFTING THE LOW NORTHEASTWARD ALONG THE GEORGIA AND
SOUTH CAROLINA COAST SUNDAY AND SUNDAY NIGHT. THE EXACT TIMING
DETAILS ARE IN QUESTION HOWEVER...WITH THE NAM AND GFS SOLUTIONS
ROUGHLY 12 HOURS FASTER THAN BOTH THE CANADIAN AND GEM SOLUTIONS.
DESPITE THE DISAGREEMENT IN TIMING OF THE SYSTEM THROUGH THE
AREA...THE MODELS ARE IN GENERAL AGREEMENT SHOWING AN INCREASE IN
DEEP MOISTURE...PRESENCE OF SOME UPPER LEVEL FORCING...AND DECENT
ISENTROPIC ASCENT OVERSPREADING THE AREA LATE SATURDAY AFTERNOON
THROUGH SUNDAY. EXPECT THAT SHOWERS WILL BE SLOW TO DEVELOP
INITIALLY WITH LACK OF DEEP MOISTURE IN PLACE ON SATURDAY...BUT
COULD SEE SOME ISOLATED SHOWERS BY LATE AFTERNOON...SO HAVE INCLUDED
SLIGHT CHANCE POPS TO ACCOUNT FOR THIS. RAIN PROBABILITIES LOOK TO
INCREASE SATURDAY NIGHT AND SUNDAY...AND HAVE CARRIED LIKELY POPS
ACROSS THE ENTIRE FORECAST AREA. AS THE SYSTEM BEGINS PULLING AWAY
FROM THE REGION SUNDAY NIGHT...RAIN PROBABILITIES SHOULD BEGIN TO
DECREASE...SO HAVE KEPT POPS WITHIN THE CHANCE RANGE.
MODEL SOLUTIONS DIFFER SIGNIFICANTLY THROUGH MUCH OF THE UPCOMING
WORK WEEK. THE ECMWF AND CANADIAN MODELS SHOW HIGH PRESSURE WEDGING
BACK INTO THE REGION MONDAY THROUGH TUESDAY...WITH A SOUTHERN STREAM
WAVE THEN LIFTING NORTHEAST OUT OF THE GULF OF MEXICO AND POSSIBLY
IMPACTING THE AREA WEDNESDAY AND THURSDAY. THE GFS ON THE OTHER HAND
BUILDS HIGH PRESSURE BACK INTO THE AREA MONDAY THROUGH THURSDAY AND
KEEPS THE FORECAST AREA RAIN FREE. GIVEN THE HIGH DEGREE OF
UNCERTAINTY THIS FAR OUT...WILL FOLLOW A PERSISTENCE FORECAST AND
KEEP THE THINGS RAIN FREE. FUTURE SHIFTS MAY NEED TO ADD RAIN
CHANCES TO THE FORECAST TUESDAY NIGHT THROUGH THURSDAY IF THE
SOUTHERN STREAM WAVE OF LOW PRESSURE DOES INDEED DEVELOP AND TRACK
NORTHEAST ACROSS THE REGION.
&&
.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
AT KCHS...SFC VSBY HAD IMPROVED TO NEAR 1SM AS WINDS HAVE PICKED
UP RECENTLY AND RUC 1000 MB GEOSTROPHIC FLOW WAS CLOSE TO 20 KT AT
11Z. THE STRATUS DECK STILL COULD BE A BIT SLOW TO LIFT AND
DISSIPATE THIS MORNING AND WE SHOWED LOW CLOUDS/IFR ENDING AROUND
1530Z. VFR IS ANTICIPATED THIS AFTERNOON AND EVENING. MVFR OR IFR
MAY RETURN AFTER 08Z/21 AS GFS/SREF MODELS SUGGEST. WE HAVE
INTRODUCED SOME LATE NIGHT MVFR AT THIS POINT.
AT KSAV...EXPANSIVE AREA OF STRATUS AND FOG IN SOUTH CAROLINA IS
STILL PLOWING SOUTH AT DAWN THIS MORNING. STRATUS AND/OR FOG
STILL COULD REACH THE TERMINAL BETWEEN 13Z-14Z BUT BY THAT TIME IT
LOOKS LIKE SURFACE DEW POINT DEPRESSIONS WILL BE ON A STEADY
INCLINE. THE REMAINDER OF THE 12Z TAF CYCLE LOOKS VFR AND WILL
NEED TO MONITOR FOR SOME VERY LATE NIGHT LOW CLOUDS EARLY SAT.
EXTENDED AVIATION OUTLOOK...MVFR OR LOWER CEILINGS AND VSBYS
POSSIBLE SAT THROUGH MON. VFR THEREAFTER.
&&
.MARINE...
IMMEDIATE CONCERN IS THE FOG ADJACENT TO THE S CAROLINA COAST. WITH
DENSE FOG REPORTED IN THE CHARLESTON HARBOR WE HAVE ISSUED AN
ADVISORY THERE MUCH EARLIER. SATELLITE IMAGERY INDICATES LOW STRATUS
AND VSBYS LIKELY BELOW 1 NM EXTENDING OVER THE ADJACENT COASTAL
WATERS. TO BE ON THE SAFE SIDE WE EXPANDED OUR MARINE FOG ADVISORY
TO INCLUDE THE NEAR SHORE SOUTH CAROLINA COASTAL LEGS.
OTHERWISE...WINDS WILL VEER TO N AND NE TODAY WITH SPEEDS MOSTLY IN
THE 10 TO 15 KT RANGE. THERE IS ALREADY A 2 FT SWELL EVERY 9-11 SECONDS
AND SEAS SHOULD AVERAGE 2-4 FT WITHIN 20 NM TODAY WITH 3-5 FT OVER OUR
GEORGIA WATERS BEYOND 20 NM...HIGHEST SEAS BEYOND 40 NM. WE SHOULD SEE
A BIT OF PINCHING GRADIENT LATER TODAY AS TEMPERATURE AND MOISTURE
GRADIENTS TIGHTEN. OVERALL WE SHOULD SEE NE FLOW 15 KT WITH SEAS 3-5
FT.
SATURDAY THROUGH TUESDAY...AN AREA OF LOW PRESSURE WILL DEVELOP
ACROSS THE NORTHERN GULF COAST OVER THE WEEKEND...WHILE SURFACE HIGH
PRESSURE TO THE NORTH MAINTAINS AN INLAND WEDGE. THIS AREA OF LOW
PRESSURE WILL LIFT NORTHEAST AND LIKELY PROGRESS ALONG THE
GEORGIA/SOUTH CAROLINA COASTLINE SUNDAY AND SUNDAY NIGHT. HIGH
PRESSURE WILL THEN BUILD BACK INTO THE AREA NEXT WEEK.
WINDS AND/OR SEAS COULD APPROACH SMALL CRAFT LEVELS ACROSS PORTIONS
OF THE WATERS SATURDAY THROUGH SUNDAY AS THE AREA OF LOW PRESSURE
ALLOWS THE GRADIENT TO PINCH FAIRLY WELL AS IT APPROACHES THE
REGION. IMPROVING CONDITIONS ARE THEN ANTICIPATED SUNDAY NIGHT
THROUGH TUESDAY...WITH WINDS AND SEAS REMAINING BELOW SMALL CRAFT
THRESHOLDS.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...DENSE FOG ADVISORY UNTIL 9 AM EST THIS MORNING FOR SCZ043>045-
048>050.
MARINE...DENSE FOG ADVISORY UNTIL 9 AM EST THIS MORNING FOR AMZ330-350-
352.
&&
$$
000
FXUS62 KCAE 201153
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
653 AM EST FRI NOV 20 2009
.SYNOPSIS...
HIGH PRESSURE WILL COVER THE AREA TODAY AND TONIGHT. LOW PRESSURE
IN THE GULF OF MEXICO WILL SPREAD CLOUDS AND A CHANCE OF RAIN BY
LATE SATURDAY. THE LOW WILL MOVE NORTHEAST SATURDAY NIGHT AND
SUNDAY WITH RAIN EXPECTED OVER THE REGION. THE LOW WILL BEGIN TO
MOVE AWAY SUNDAY NIGHT AND HIGH PRESSURE WILL RETURN FOR MONDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
HIGH PRESSURE WILL COVER THE REGION. SOME LOW LEVEL MOISTURE THIS
MORNING WILL ALLOW SOME PATCHY DENSE FOG TO DEVELOP NEAR RIVERS
AND STREAMS BUT WIDESPREAD DENSE FOG IS NOT EXPECTED, HIGHS THIS
AFTERNOON WILL BE IN THE UPPER 60S TO LOWER 70S.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/...
HIGH PRESSURE OVER THE AREA WILL WEAKEN OVERNIGHT. A DEVELOPING
LOW PRESSURE AREA IN THE NORTHERN GULF OF MEXICO WILL SPREAD
CLOUDS AND A CHANCE OF RAIN TO THE REGION BY LATE IN THE DAY ON
SATURDAY. SATURDAY WILL BE COOLER WITH HIGH TEMPERATURES IN THE
LOWER TO MIDDLE 60S. A 70-80 PERCENT CHANCE OF RAIN IS EXPECTED
SATURDAY NIGHT AND SUNDAY AS THE LOW MOVES NORTHEAST OFF THE SOUTH
CAROLINA COAST. NOT MUCH CHANGE IN TEMPERATURES SATURDAY NIGHT
WITH LOWS IN THE UPPER 40S TO LOWER 50S. SUNDAY HIGHS ARE IN THE
50S. QPF VALUES ARE UP TO AROUND ONE INCH BY SUNDAY.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
IN GOOD AGREEMENT WITH LONG RANGE MODELS. AFTER SYSTEM MOVES AWAY
SUNDAY NIGHT...ZONAL FLOW WITH SURFACE HIGH PRESSURE MONDAY GIVE
WAY TO UPPER SOUTHWEST FLOW TUESDAY AS A DRY COLD FRONT APPROACHES
TUESDAY NIGHT. HIGH PRESSURE MOVES IN FOR WEDNESDAY AND
THANKSGIVING DAY. TEMPERATURES START OFF A FEW DEGREES ABOVE
NORMAL WITH HIGHS UP NEAR 70 MONDAY AND TUESDAY WITH LOWS IN THE
40S. COOLER CONDITIONS EXPECTED BY WEDNESDAY AND THANKSGIVING DAY
WITH HIGHS CLOSER TO 60 AND LOWS IN THE UPPER 30S TO LOWER 40S.
&&
.AVIATION /12Z FRIDAY THROUGH WEDNESDAY/...
OBS/SATELLITE SHOW AREA OF FOG ACRS THE NRN MIDLANDS/PIEDMONT. FOG
EXTENDS AS FAR SW AS THE CAE/CUB AREA. FOG WILL DISSIPATE BETWEEN
13Z-14Z WITH VFR CONDITIONS EXPECT AT ALL SITES. VFR CONDITIONS
SHOULD CONTINUE THROUGH THE REMAINDER OF THE PERIOD.
EXTENDED AVIATION OUTLOOK...WIDESPREAD MVFR OR IFR CONDITIONS WILL
LIKELY OCCUR SATURDAY NIGHT AND SUNDAY ASSOCIATED WITH AN AREA OF
LOW PRESSURE EXPECTED TO MOVE NORTHEASTWARD FROM THE GULF OF MEXICO.
CONDITIONS SHOULD IMPROVE SUNDAY NIGHT WITH ISSUES EXPECTED THROUGH
THE REMAINDER OF THE PERIOD.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
000
FXUS62 KFFC 201025
AFDFFC
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
520 AM EST FRI NOV 20 2009
.SHORT TERM /TODAY THROUGH SUNDAY/...
SHORT TERM MODELS IN GOOD AGREEMENT AS FAR AS DEVELOPMENT OF THE
UPPER LEVEL CURRENTLY ROTATING OVER WEST TEXAS. NAM/GFS DEEPENING
THE LOW THROUGH TONIGHT ACROSS NORTH TEXAS BEFORE CLOSING THE LOW
OVER EAST TEXAS BY SATURDAY MORNING. WHILE ECMWF AND CANADIAN AGREE
WITH THE GENERAL TRACK OF THE SYSTEM...THEY NEVER CLOSE THE UPPER
LOW. SURFACE HIGH PRESSURE BEGINS TO SHIFT NORTHWARD TODAY...AND
THEN NORTHEAST OVERNIGHT AS AN INVERTED TROUGH IS PUSHED INTO THE
NORTHWEST GULF BY TOMORROW MORNING. AS THE UPPER LOW INTENSIFIES...
THE SURFACE LOW CLOSES OFF AND BEGINS TO LIFT NORTHEASTWARD INTO
SOUTHERN MISSISSIPPI AND ALABAMA BY TOMORROW EVENING. SOUTHWEST
FLOW ALOFT INCREASES MOISTURE AT THE UPPER LEVELS...WHILE LOW
LEVEL MOISTURE RETURNS DURING THE DAY ON SATURDAY. ALL MODELS SEEM
TO AGREE THAT SURFACE HIGH WHICH SHIFTS OVER SOUTHERN CANADA BY
SUNDAY WILL SET UP WEAK COLD AIR DAMMING OVER THE CAROLINAS AND
PORTIONS OF NORTHEAST GEORGIA SATURDAY NIGHT INTO SUNDAY AS THE
WARM FRONT LIFTS NORTHWARD. MAIN QUESTION IS HOW FAR NORTH THE
WARM FRONT WILL MAKE IT AND HOW STRONG THE WEDGE FRONT WILL BE AS
THIS WILL DELINEATE BEST AREAS FOR CONVECTION. GFS/NAM WEAKER WITH
WEDGING AND BRING THE WARM FRONT INTO PORTIONS OF CENTRAL GEORGIA
AT THIS TIME. ALTHOUGH INSTABILITY IS MINIMAL...SHEAR IS QUITE
HIGH SATURDAY NIGHT AND SUNDAY MORNING. WILL ADD ISOLATED THUNDER
WORDING TO FORECAST AT THIS TIME...MAINLY ALONG AND SOUTH OF A
COLUMBUS TO MACON LINE. HAVE LEANED HEAVILY TOWARD THE NAM/GFS
SOLUTIONS. MODELS ARE VERY SIMILAR AND MAV/MET TEMPERATURES ARE
THE SAME AT SEVERAL LOCATIONS. WILL NOT STRAY VERY FAR FROM
GUIDANCE THROUGH THE SHORT TERM PERIODS.
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
THE SHORT WAVE ROTATES NORTHWARD SUNDAY NIGHT...WITH EXTENDED MODELS
DIVERGING ON HOW QUICKLY THE MOISTURE REMAINS AND HOW QUICKLY THE
SURFACE HIGH CAN BUILD INTO THE AREA. FOR NOW WILL CONTINUE TO LEAN
TOWARD THE GFS AS ECMWF/CANADIAN SLOW TO ERODE EASTERLY FLOW ACROSS
EVEN THOUGH SURFACE HIGH IS LOCATED OVER NOVA SCOTIA. DRIER AIR AND
SURFACE HIGH PRESSURE WILL WORK INTO THE AREA MONDAY AS THE NEXT
SYSTEM PREPARES TO CROSS THE NORTHERN PLAINS. THE BULK OF THIS
SYSTEM REMAINS NORTH WITH LIMITED RETURN FLOW OR MOISTURE. WEAK
SURFACE FRONT PUSHES ACROSS THE AREA ON TUESDAY WITH SLIGHT CHANCE
OF SHOWERS POSSIBLE...OTHERWISE DRY CONDITIONS EXPECTED LEADING UP
TO THANKSGIVING. GUIDANCE TEMPERATURES ARE NEAR NORMAL THROUGH THE
END OF THE PERIOD WHEN STRONG COLD AIR ADVECTION ASSOCIATED WITH A
BROAD SURFACE HIGH COULD BRING SLIGHTLY COOLER TEMPERATURES.
&&
.AVIATION...
DRY AIR CONTINUING OVER GA TODAY WITH CLEAR SKIES EXPECTED. MID/HIGH
CLOUDS INCREASING ACROSS WESTERN GA AFTER 00Z SATURDAY. VISIBILITY
UNRESTRICTED EXCEPT FOR LOCAL 3 TO 5SM IN FOG UNTIL 14Z THIS
MORNING. WINDS NORTHWEST 5 TO 10KT THIS MORNING BECOMING NORTHEAST 5
TO 10KT AFTER 18Z.
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 67 42 62 48 53 / 0 0 20 100 70
ATLANTA 66 45 62 48 56 / 0 0 50 100 50
BLAIRSVILLE 63 39 57 47 50 / 0 0 20 100 60
CARTERSVILLE 66 40 59 47 56 / 0 0 50 100 50
COLUMBUS 69 48 65 55 64 / 0 0 70 100 40
GAINESVILLE 65 44 61 47 51 / 0 0 20 100 60
MACON 70 43 66 54 63 / 0 0 30 100 60
ROME 66 39 61 50 57 / 0 0 50 100 50
PEACHTREE CITY 67 38 60 49 58 / 0 0 60 100 50
VIDALIA 72 44 66 54 72 / 0 0 20 90 70
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
12/41
000
FXUS62 KCHS 200914
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
414 AM EST FRI NOV 20 2009
.SYNOPSIS...
HIGH PRES WILL BUILD N OF THE REGION THROUGH TONIGHT. A GULF LOW
PRES SYSTEM WILL DEVELOP ON SAT THEN MOVE NE ALONG THE SOUTHEAST
COAST SUNDAY AND SUNDAY NIGHT. HIGH PRES WILL THEN BUILD BACK INTO
THE AREA FROM THE W EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
SATELLITE IMAGERY INDICATES LOW CLOUDS/STRATUS SINKING S OVER THE
CHARLESTON TRI-COUNTY REGION...ESPECIALLY TO THE E OF I-95 AND TO
THE NORTH OF BEAUFORT THIS MORNING. VSBYS ALONG THE I-95 CORRIDOR
FROM ST. GEORGE E...WERE DOWN TO 1/4 MILE OR LESS OVER PARTS OF
BERKELEY AND DORCHESTER COUNTIES. DENSE FOG RECENTLY REPORTED AT
THE CHARLESTON AIRPORT DOWN TO THE HARBOR...DENSE FOG NOW
DEVELOPING IN COLLETON COUNTY. WE MAINTAINED THE DENSE FOG
ADVISORY FOR OUR 3 INLAND SOUTH CAROLINA ZONES AND ADDED
CHARLESTON COUNTY. AREAS OF FOG MAY DEVELOP OVER THE REMAINDER OF
OUR FORECAST AREA TOWARD DAWN...BUT WIDESPREAD DENSE FOG SEEMS
UNLIKELY IN FAR SOUTHERN SOUTH CAROLINA AND SE GEORGIA.
AFTER THE FOG DISSIPATES AFTER MID MORNING...SOME AREAS OF
STRATUS MAY TAKE ANOTHER HOUR OR TWO TO BURN OFF IN PLACES LIKE
JAMESTOWN AND AROUND LAKE MOULTRIE. OTHERWISE...WE THINK OUR
REGION WILL SEE MOSTLY SUNNY SKIES WITH A WEAK COLD AIR ADVECTION
PATTERN. HIGH PRES BUILDING TO OUR NW AND N WILL KEEP AFTERNOON
TEMPERATURES CLOSER TO 70 WITH HIGHS MANY AREAS IN THE LOWER 70S.
BEACHES WILL SHARE IN THE SUNSHINE THIS AFTERNOON...BUT READINGS
WILL ONLY BE IN THE LOWER TO MID 60S WITH NE BREEZES KICKING IN.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SATURDAY/...
WE MAINTAINED A DRY FORECAST TONIGHT WITH A GRADUALLY INCREASE IN
CLOUDS. HIGH CLOUDS AT FIRST...THEN INCREASES IN STRATOCUMULUS
CLOSER TO THE COAST LATE WITH POTENTIAL FOR MORE INLAND STRATUS
FORMATION LATE. WEAK ISENTROPIC LIFT IS FORECAST TO DEVELOP OFF
THE GEORGIA COAST LATE AND THERE APPEARS TO BE A BOUNDARY LAYER
WARM FRONT TRYING TO DEVELOP TOWARD DAWN ON SAT SOMEWHERE NEAR
JACKSONVILLE OR BRUNSWICK GEORGIA. WE MADE FEW CHANGES TO OUR LOW
TEMPERATURE FORECAST SCHEME WITH 45-49 INLAND AND SOME LOWER 50S
ALONG THE U.S 17 CORRIDOR. NE FLOW WILL KEEP BEACHES MILDER...CLOSER
TO 60 DEGREES FROM EDISTO S TO THE GEORGIA BARRIER ISLANDS.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
MEDIUM RANGE GUIDANCE AGREEMENT LEAVES A LOT TO BE DESIRED THIS
MORNING...WITH THE VARIOUS SOLUTIONS STRUGGLING WITH TIMING AND
POSITION DETAILS OF SYNOPTIC FEATURES THROUGH MOST OF THE EXTENDED
PERIODS. AS A RESULT...FORECAST CONFIDENCE WILL REMAIN LOWER THAN
NORMAL THROUGH THE PERIOD.
GUIDANCE SOLUTIONS ARE IN GOOD AGREEMENT DEVELOPING AN AREA OF LOW
PRESSURE ALONG THE NORTHERN GULF COAST SATURDAY AND SATURDAY
NIGHT...THEN LIFTING THE LOW NORTHEASTWARD ALONG THE GEORGIA AND
SOUTH CAROLINA COAST SUNDAY AND SUNDAY NIGHT. THE EXACT TIMING
DETAILS ARE IN QUESTION HOWEVER...WITH THE NAM AND GFS SOLUTIONS
ROUGHLY 12 HOURS FASTER THAN BOTH THE CANADIAN AND GEM SOLUTIONS.
DESPITE THE DISAGREEMENT IN TIMING OF THE SYSTEM THROUGH THE
AREA...THE MODELS ARE IN GENERAL AGREEMENT SHOWING AN INCREASE IN
DEEP MOISTURE...PRESENCE OF SOME UPPER LEVEL FORCING...AND DECENT
ISENTROPIC ASCENT OVERSPREADING THE AREA LATE SATURDAY AFTERNOON
THROUGH SUNDAY. EXPECT THAT SHOWERS WILL BE SLOW TO DEVELOP
INITIALLY WITH LACK OF DEEP MOISTURE IN PLACE ON SATURDAY...BUT
COULD SEE SOME ISOLATED SHOWERS BY LATE AFTERNOON...SO HAVE INCLUDED
SLIGHT CHANCE POPS TO ACCOUNT FOR THIS. RAIN PROBABILITIES LOOK TO
INCREASE SATURDAY NIGHT AND SUNDAY...AND HAVE CARRIED LIKELY POPS
ACROSS THE ENTIRE FORECAST AREA. AS THE SYSTEM BEGINS PULLING AWAY
FROM THE REGION SUNDAY NIGHT...RAIN PROBABILITIES SHOULD BEGIN TO
DECREASE...SO HAVE KEPT POPS WITHIN THE CHANCE RANGE.
MODEL SOLUTIONS DIFFER SIGNIFICANTLY THROUGH MUCH OF THE UPCOMING
WORK WEEK. THE ECMWF AND CANADIAN MODELS SHOW HIGH PRESSURE WEDGING
BACK INTO THE REGION MONDAY THROUGH TUESDAY...WITH A SOUTHERN STREAM
WAVE THEN LIFTING NORTHEAST OUT OF THE GULF OF MEXICO AND POSSIBLY
IMPACTING THE AREA WEDNESDAY AND THURSDAY. THE GFS ON THE OTHER HAND
BUILDS HIGH PRESSURE BACK INTO THE AREA MONDAY THROUGH THURSDAY AND
KEEPS THE FORECAST AREA RAIN FREE. GIVEN THE HIGH DEGREE OF
UNCERTAINTY THIS FAR OUT...WILL FOLLOW A PERSISTENCE FORECAST AND
KEEP THE THINGS RAIN FREE. FUTURE SHIFTS MAY NEED TO ADD RAIN
CHANCES TO THE FORECAST TUESDAY NIGHT THROUGH THURSDAY IF THE
SOUTHERN STREAM WAVE OF LOW PRESSURE DOES INDEED DEVELOP AND TRACK
NORTHEAST ACROSS THE REGION.
&&
.AVIATION /08Z FRIDAY THROUGH TUESDAY/...
DENSE FOG HAD DEVELOPED AT THE CHARLESTON AIRPORT RECENTLY
AND VSBYS BELOW 1/2 NM SHOULD REMAIN COMMON UNTIL MID MORNING.
EVEN IF VSBYS IMPROVE AT TIMES...STRATUS CIGS BELOW 400 FT
WILL PERSIST. KSAV IS STILL VFR BUT WE THINK A SUNRISE WINDOW
FOR MVFR OR IFR VSBYS IS LIKELY. WIDESPREAD IFR CIGS DO NOT
APPEAR TO BE SHIFTING AS FAR S OF KSAV BUT WE WILL CONTINUE
TO MONITOR.
THE FOG SHOULD BURN OFF FAIRLY QUICKLY AFTER SUNRISE WITH
CONDITIONS RETURNING TO VFR AFTER 14-15Z...CONTINUING INTO
FRI EVENING.
EXTENDED AVIATION OUTLOOK...MVFR OR LOWER CEILINGS AND VISIBILITIES
POSSIBLE SAT THROUGH MONDAY. VFR THEREAFTER.
&&
.MARINE...
IMMEDIATE CONCERN IS THE FOG ADJACENT TO THE S CAROLINA COAST. WITH
DENSE FOG RECENTLY REPORTED IN THE CHARLESTON HARBOR WE HAVE ISSUED
AN ADVISORY THERE. TOUCH AND GO ALONG THE REMAINDER OF THE CHARLESTON
COUNTY COAST AND WE HAVE MENTIONED FOG IN THE MORNING FORECAST.
OTHERWISE...WINDS WILL VEER TO N AND NE TODAY WITH SPEEDS MOSTLY IN
THE 10 TO 15 KT RANGE. THERE IS ALREADY A 2 FT SWELL EVERY 9-11 SECONDS
AND SEAS SHOULD AVERAGE 2-4 FT WITHIN 20 NM TODAY WITH 3-5 FT OVER OUR
GEORGIA WATERS BEYOND 20 NM...HIGHEST SEAS BEYOND 40 NM. WE SHOULD SEE
A BIT OF PINCHING GRADIENT LATER TODAY AS TEMPERATURE AND MOISTURE
GRADIENTS TIGHTEN. OVERALL WE SHOULD SEE NE FLOW 15 KT WITH SEAS 3-5
FT.
SATURDAY THROUGH TUESDAY...AN AREA OF LOW PRESSURE WILL DEVELOP
ACROSS THE NORTHERN GULF COAST OVER THE WEEKEND...WHILE SURFACE HIGH
PRESSURE TO THE NORTH MAINTAINS AN INLAND WEDGE. THIS AREA OF LOW
PRESSURE WILL LIFT NORTHEAST AND LIKELY PROGRESS ALONG THE
GEORGIA/SOUTH CAROLINA COASTLINE SUNDAY AND SUNDAY NIGHT. HIGH
PRESSURE WILL THEN BUILD BACK INTO THE AREA NEXT WEEK.
WINDS AND/OR SEAS COULD APPROACH SMALL CRAFT LEVELS ACROSS PORTIONS
OF THE WATERS SATURDAY THROUGH SUNDAY AS THE AREA OF LOW PRESSURE
ALLOWS THE GRADIENT TO PINCH FAIRLY WELL AS IT APPROACHES THE
REGION. IMPROVING CONDITIONS ARE THEN ANTICIPATED SUNDAY NIGHT
THROUGH TUESDAY...WITH WINDS AND SEAS REMAINING BELOW SMALL CRAFT
THRESHOLDS.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...DENSE FOG ADVISORY UNTIL 9 AM EST THIS MORNING FOR SCZ043>045-
050.
MARINE...DENSE FOG ADVISORY UNTIL 9 AM EST THIS MORNING FOR AMZ330.
&&
$$
JRJ
000
FXUS62 KCAE 200859
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
359 AM EST FRI NOV 20 2009
.SYNOPSIS...
HIGH PRESSURE WILL COVER THE AREA TODAY AND TONIGHT. LOW PRESSURE
IN THE GULF OF MEXICO WILL SPREAD CLOUDS AND A CHANCE OF RAIN BY
LATE SATURDAY. THE LOW WILL MOVE NORTHEAST SATURDAY NIGHT AND
SUNDAY WITH RAIN EXPECTED OVER THE REGION. THE LOW WILL BEGIN TO
MOVE AWAY SUNDAY NIGHT AND HIGH PRESSURE WILL RETURN FOR MONDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
HIGH PRESSURE WILL COVER THE REGION. SOME LOW LEVEL MOISTURE THIS
MORNING WILL ALLOW SOME PATCHY DENSE FOG TO DEVELOP NEAR RIVERS
AND STREAMS BUT WIDESPREAD DENSE FOG IS NOT EXPECTED, HIGHS THIS
AFTERNOON WILL BE IN THE UPPER 60S TO LOWER 70S.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/...
HIGH PRESSURE OVER THE AREA WILL WEAKEN OVERNIGHT. A DEVELOPING
LOW PRESSURE AREA IN THE NORTHERN GULF OF MEXICO WILL SPREAD
CLOUDS AND A CHANCE OF RAIN TO THE REGION BY LATE IN THE DAY ON
SATURDAY. SATURDAY WILL BE COOLER WITH HIGH TEMPERATURES IN THE
LOWER TO MIDDLE 60S. A 70-80 PERCENT CHANCE OF RAIN IS EXPECTED
SATURDAY NIGHT AND SUNDAY AS THE LOW MOVES NORTHEAST OFF THE SOUTH
CAROLINA COAST. NOT MUCH CHANGE IN TEMPERATURES SATURDAY NIGHT
WITH LOWS IN THE UPPER 40S TO LOWER 50S. SUNDAY HIGHS ARE IN THE
50S. QPF VALUES ARE UP TO AROUND ONE INCH BY SUNDAY.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
IN GOOD AGREEMENT WITH LONG RANGE MODELS. AFTER SYSTEM MOVES AWAY
SUNDAY NIGHT...ZONAL FLOW WITH SURFACE HIGH PRESSURE MONDAY GIVE
WAY TO UPPER SOUTHWEST FLOW TUESDAY AS A DRY COLD FRONT APPROACHES
TUESDAY NIGHT. HIGH PRESSURE MOVES IN FOR WEDNESDAY AND
THANKSGIVING DAY. TEMPERATURES START OFF A FEW DEGREES ABOVE
NORMAL WITH HIGHS UP NEAR 70 MONDAY AND TUESDAY WITH LOWS IN THE
40S. COOLER CONDITIONS EXPECTED BY WEDNESDAY AND THANKSGIVING DAY
WITH HIGHS CLOSER TO 60 AND LOWS IN THE UPPER 30S TO LOWER 40S.
&&
.AVIATION /09Z FRIDAY THROUGH TUESDAY/...
EXPECT FOG DEVELOPMENT OVERNIGHT ACROSS TAF SITES. SATELLITE SHOWING
AREAS OF FOG ALREADY OCCURRING ACROSS THE NORTHERN MIDLANDS AND PEE
DEE...NORTH OF CAE/CUB. WITH RH VALUES NEAR 100 PERCENT...CLEAR
SKIES AND LIGHT WINDS...EXPECT FOG TO DEVELOP ACRS THE AREA.
GUIDANCE INDICATES LOWEST VSBYS WILL BE ACRS THE MIDLANDS. SHOULD
SEE MVFR/IFR CONDITIONS AT CAE/CUB/AGS/DNL AND LIFR CONDITIONS AT
OGB. AFTER SUNRISE...HEATING AND MIXING SHOULD RESULT IN A RETURN
TO VFR CONDITIONS AROUND 14Z AT ALL SITES. VFR CONDITIONS SHOULD
CONTINUE THROUGH THE REMAINDER OF THE PERIOD.
EXTENDED AVIATION OUTLOOK...WIDESPREAD MVFR OR IFR CONDITIONS WILL
LIKELY OCCUR SATURDAY NIGHT AND SUNDAY ASSOCIATED WITH AN AREA OF
LOW PRESSURE EXPECTED TO MOVE NORTHEASTWARD FROM THE GULF OF MEXICO.
CONDITIONS SHOULD IMPROVE SUNDAY NIGHT WITH ISSUES EXPECTED THROUGH
THE REMAINDER OF THE PERIOD.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
SYNOPSIS...07
NEAR TERM...07
SHORT TERM...07
LONG TERM...07
AVIATION...77
000
FXUS62 KFFC 200805
AFDFFC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
305 AM EST FRI NOV 20 2009
.SHORT TERM /TODAY THROUGH SUNDAY/...
SHORT TERM MODELS IN GOOD AGREEMENT AS FAR AS DEVELOPMENT OF THE
UPPER LEVEL CURRENTLY ROTATING OVER WEST TEXAS. NAM/GFS DEEPENING
THE LOW THROUGH TONIGHT ACROSS NORTH TEXAS BEFORE CLOSING THE LOW
OVER EAST TEXAS BY SATURDAY MORNING. WHILE ECMWF AND CANADIAN AGREE
WITH THE GENERAL TRACK OF THE SYSTEM...THEY NEVER CLOSE THE UPPER
LOW. SURFACE HIGH PRESSURE BEGINS TO SHIFT NORTHWARD TODAY...AND
THEN NORTHEAST OVERNIGHT AS AN INVERTED TROUGH IS PUSHED INTO THE
NORTHWEST GULF BY TOMORROW MORNING. AS THE UPPER LOW INTENSIFIES...
THE SURFACE LOW CLOSES OFF AND BEGINS TO LIFT NORTHEASTWARD INTO
SOUTHERN MISSISSIPPI AND ALABAMA BY TOMORROW EVENING. SOUTHWEST
FLOW ALOFT INCREASES MOISTURE AT THE UPPER LEVELS...WHILE LOW
LEVEL MOISTURE RETURNS DURING THE DAY ON SATURDAY. ALL MODELS SEEM
TO AGREE THAT SURFACE HIGH WHICH SHIFTS OVER SOUTHERN CANADA BY
SUNDAY WILL SET UP WEAK COLD AIR DAMMING OVER THE CAROLINAS AND
PORTIONS OF NORTHEAST GEORGIA SATURDAY NIGHT INTO SUNDAY AS THE
WARM FRONT LIFTS NORTHWARD. MAIN QUESTION IS HOW FAR NORTH THE
WARM FRONT WILL MAKE IT AND HOW STRONG THE WEDGE FRONT WILL BE AS
THIS WILL DELINEATE BEST AREAS FOR CONVECTION. GFS/NAM WEAKER WITH
WEDGING AND BRING THE WARM FRONT INTO PORTIONS OF CENTRAL GEORGIA
AT THIS TIME. ALTHOUGH INSTABILITY IS MINIMAL...SHEAR IS QUITE
HIGH SATURDAY NIGHT AND SUNDAY MORNING. WILL ADD ISOLATED THUNDER
WORDING TO FORECAST AT THIS TIME...MAINLY ALONG AND SOUTH OF A
COLUMBUS TO MACON LINE. HAVE LEANED HEAVILY TOWARD THE NAM/GFS
SOLUTIONS. MODELS ARE VERY SIMILAR AND MAV/MET TEMPERATURES ARE
THE SAME AT SEVERAL LOCATIONS. WILL NOT STRAY VERY FAR FROM
GUIDANCE THROUGH THE SHORT TERM PERIODS.
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
THE SHORT WAVE ROTATES NORTHWARD SUNDAY NIGHT...WITH EXTENDED MODELS
DIVERGING ON HOW QUICKLY THE MOISTURE REMAINS AND HOW QUICKLY THE
SURFACE HIGH CAN BUILD INTO THE AREA. FOR NOW WILL CONTINUE TO LEAN
TOWARD THE GFS AS ECMWF/CANADIAN SLOW TO ERODE EASTERLY FLOW ACROSS
EVEN THOUGH SURFACE HIGH IS LOCATED OVER NOVA SCOTIA. DRIER AIR AND
SURFACE HIGH PRESSURE WILL WORK INTO THE AREA MONDAY AS THE NEXT
SYSTEM PREPARES TO CROSS THE NORTHERN PLAINS. THE BULK OF THIS
SYSTEM REMAINS NORTH WITH LIMITED RETURN FLOW OR MOISTURE. WEAK
SURFACE FRONT PUSHES ACROSS THE AREA ON TUESDAY WITH SLIGHT CHANCE
OF SHOWERS POSSIBLE...OTHERWISE DRY CONDITIONS EXPECTED LEADING UP
TO THANKSGIVING. GUIDANCE TEMPERATURES ARE NEAR NORMAL THROUGH THE
END OF THE PERIOD WHEN STRONG COLD AIR ADVECTION ASSOCIATED WITH A
BROAD SURFACE HIGH COULD BRING SLIGHTLY COOLER TEMPERATURES.
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 67 42 62 48 53 / 0 0 20 100 70
ATLANTA 66 45 62 48 56 / 0 0 50 100 50
BLAIRSVILLE 63 39 57 47 50 / 0 0 20 100 60
CARTERSVILLE 66 40 59 47 56 / 0 0 50 100 50
COLUMBUS 69 48 65 55 64 / 0 0 70 100 40
GAINESVILLE 65 44 61 47 51 / 0 0 20 100 60
MACON 70 43 66 54 63 / 0 0 30 100 60
ROME 66 39 61 50 57 / 0 0 50 100 50
PEACHTREE CITY 67 38 60 49 58 / 0 0 60 100 50
VIDALIA 72 44 66 54 72 / 0 0 20 90 70
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
12
000
FXUS62 KCAE 200550
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
1250 AM EST FRI NOV 20 2009
.SYNOPSIS...
HIGH PRESSURE WILL MOVE INTO THE AREA AND DOMINATE TONIGHT THROUGH
EARLY SATURDAY. A LOW PRESSURE SYSTEM WILL MOVE OUT OF THE GULF OF
MEXICO AND BRING RAIN TO THE AREA SATURDAY NIGHT THROUGH SUNDAY.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
HIGH PRESSURE CONTINUES TO ENTER THE FORECAST AREA WITH ADDITIONAL
DRYING SLOWLY MOVING THROUGH CENTRAL AND EASTERN GA. ACARS
SOUNDINGS INDICATE INVERSION ALREADY DEVELOPING WITH THE NORTHERN
MIDLANDS SEEING SOME DEVELOPING FOG. WILL KEEP AREAS OF FOG IN THE
FORECAST THROUGH THE NIGHT...HOWEVER WITH THE DRIER AIR AND LITTLE
AVAILABLE MOISTURE ON THE GROUND WILL HOLD OFF ON ISSUING ANY
DENSE FOG PRODUCTS ATTM. WILL ISSUE AN UPDATE TO ADJUST WORDING
AND TWEAK TEMPERATURES.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY/...
THE NAM AND GFS SHOW DRY RIDGING DOMINATING FRIDAY THROUGH EARLY
SATURDAY. ISENTROPIC LIFT WILL BE ON THE INCREASE SATURDAY AHEAD
OF LOW PRESSURE APPROACHING FROM THE GULF OF MEXICO. THE MAV AND
MET MOS ARE IN GOOD AGREEMENT SHOWING CHANCE POPS IN THE SOUTHWEST
SECTION TO SLIGHT CHANCE POPS IN THE NORTHEAST PART SATURDAY
AFTERNOON. USED THE GUIDANCE CONSENSUS FOR THE TEMPERATURE
FORECAST EXCEPT THE COOLER VALUES APPEARED BETTER SATURDAY BECAUSE
OF EXPECTED CLOUDINESS.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
THE GFS AND ECMWF SHOW HIGH MOISTURE SUNDAY ASSOCIATED WITH LOW
PRESSURE MOVING THROUGH THE AREA. THE MODELS SHOW A DRY PATTERN
DURING THE REST OF THE PERIOD. THE GFS ENSEMBLES INDICATE SEASONABLE
TEMPERATURES.
&&
.AVIATION /06Z FRIDAY THROUGH WEDNESDAY/...
EXPECT FOG DEVELOPMENT OVERNIGHT ACROSS TAF SITES. SATELLITE SHOWING
AREAS OF FOG ALREADY OCCURRING ACROSS THE NORTHERN MIDLANDS AND PEE
DEE...NORTH OF CAE/CUB. WITH RH VALUES NEAR 100 PERCENT...CLEAR
SKIES AND LIGHT WINDS...EXPECT FOG TO DEVELOP ACRS THE AREA.
GUIDANCE INDICATES LOWEST VSBYS WILL BE ACRS THE MIDLANDS. SHOULD
SEE MVFR/IFR CONDITIONS AT CAE/CUB/AGS/DNL AND LIFR CONDITIONS AT
OGB. AFTER SUNRISE...HEATING AND MIXING SHOULD RESULT IN A RETURN
TO VFR CONDITIONS AROUND 14Z AT ALL SITES. VFR CONDITIONS SHOULD
CONTINUE THROUGH THE REMAINDER OF THE PERIOD.
EXTENDED AVIATION OUTLOOK...WIDESPREAD MVFR OR IFR CONDITIONS WILL
LIKELY OCCUR SATURDAY NIGHT AND SUNDAY ASSOCIATED WITH AN AREA OF
LOW PRESSURE EXPECTED TO MOVE NORTHEASTWARD FROM THE GULF OF MEXICO.
CONDITIONS SHOULD IMPROVE SUNDAY NIGHT WITH ISSUES EXPECTED THROUGH
THE REMAINDER OF THE PERIOD.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
000
FXUS62 KCHS 200543
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
1243 AM EST FRI NOV 20 2009
.SYNOPSIS...
WEAK HIGH PRESSURE WILL BUILD NORTH OF THE REGION TONIGHT THROUGH
FRIDAY. A GULF LOW PRESSURE SYSTEM WILL DEVELOP ON SATURDAY AND
POSSIBLY MOVE UP THE SOUTHEAST COAST SUNDAY INTO MONDAY. HIGH
PRESSURE WILL BUILD IN FROM THE WEST NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
VISIBILITIES ARE SLOWLY LOWERING ACROSS THE AREA THIS EVENING AS
TEMPERATURES APPROACH CROSS-OVER TEMPERATURES IN THE UPPER 50S.
CONDITIONS APPEAR FAVORABLE FOR FOG TO DEVELOP AS THE BOUNDARY
LAYER SATURATES AND THE NOCTURNAL INVERSION INTENSIFIES. 1000MB
GEOSTROPHIC WINDS ARE FORECAST TO INCREASE TO 15-20 KT SHORTLY
AFTER 5 AM...WHICH MAY TRANSITION SOME OF THE FOG INTO A VERY LOW
STRATUS DECK PRIOR TO SUNRISE. COMPLICATING MATTERS ARE THE HIGH
CLOUDS STREAMING IN FROM THE SOUTH ASSOCIATED WITH A MODEST
SUBTROPICAL JET. THESE CLOUDS ARE FORECAST REMAIN ACROSS MAINLY
THE CENTRAL/SOUTHERN PARTS OF THE FORECAST AREA AND WILL ALSO HELP
DELAY AND/OR LIMIT THE DENSE FOG POTENTIAL. PLAN TO STICK WITH
AREAS OF FOG FOR THESE AREAS BUT INCLUDE A MENTION OF PATCHY DENSE
FOG WITH VISIBILITIES OCCASIONALLY DROPPING BELOW 1/4 MILE AT
TIMES.
ACROSS THE FAR NORTH...THERE LOOKS TO A ENOUGH OF A POTENTIAL FOR
WIDESPREAD DENSE FOG TO DEVELOP MUCH OF BERKELEY/DORCHESTER AND
INLAND COLLETON COUNTIES TO JUSTIFY A DENSE FOG ADVISORY ATTM
SINCE THE BULK OF THE HIGH CLOUDS ARE PROGGED TO REMAIN TO THE
SOUTH. ALL AVAILABLE SHORT TERM GUIDANCE PACKAGES SUGGEST
WIDESPREAD VISIBILITIES OF 1/4 MILE OR LESS WILL DEVELOP SHORTLY
AFTER 1 AM AND CONSIDERING OBSERVATIONS OUT OF KINGSTREE HAVE BEEN
CONSISTENTLY 1/4 MILE OR LESS FOR THE PAST FEW HOURS...CONFIDENCE
IS INCREASING THAT ADVISORY LEVEL CONDITIONS WILL BE MET. WILL
KEEP THE ADVISORY OUT OF THE CHARLESTON METRO AREA FOR NOW...BUT
IT MAY VERY WELL HAVE TO BE EXPANDED TO INCLUDE ADJACENT COUNTIES
LATER TONIGHT. WILL RUN THE ADVISORY FROM 1 AM UNTIL 9 AM
FRIDAY...BUT THIS MAY HAVE TO BE ADJUSTED DEPENDING ON HOW THE
FOG REACTS TO INCREASING 1000MB GEOSTROPHIC WINDS PRIOR TO SUNRISE
FRIDAY.
WILL NUDGE OVERNIGHT LOWS UP A FEW DEGREES PER GOING TRENDS. EXPECT
LOWS FROM THE MID 40S FAR WEST INTERIOR TO THE UPPER 50S/NEAR 60
AT THE COAST.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM SATURDAY/...
BROAD SOUTHWESTERLY FLOW WILL CONTINUE ALOFT ON FRIDAY WHILE
SURFACE HIGH PRESSURE CONTINUES TO BUILD NORTH OF THE REGION. WEAK
NVA AND SUBSIDENCE SHOULD PROVIDE FOR MOSTLY SUNNY SKIES MUCH OF
THE DAY. HOWEVER A NORTHERLY FLOW WILL KEEP HIGHS FROM RISING OUT
OF THE LOWER 70S.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
MAIN CONCERN DURING THE EXTENDED PERIOD WILL FALL BETWEEN SATURDAY
NIGHT AND MONDAY...AS AN UPPER SHORTWAVE DEVELOPS OVER THE GULF OF
MEXICO AND TRACKS NORTH/NORTHEAST THROUGH THE WEEKEND. AS THE
SURFACE REFLECTION OF THIS UPPER LOW TAKES SHAPE ALONG THE GULF
COAST STATES...HIGH PRESSURE TO THE NORTH OF THE FORECAST AREA
WILL MAINTAIN INLAND SURFACE RIDGING. MOST OF THE UNCERTAINTY
CONCERNING THE EVOLUTION OF THIS SYSTEM REVOLVES AROUND WHETHER
THE SURFACE LOW WILL BE STRONG ENOUGH TO PUSH THROUGH THE
WEDGE...OR REDEVELOP ALONG THE SOUTHEAST COAST.
THE STRONGER GFS SOLUTION INDICATES A SURFACE LOW PUNCHING INTO THE
INLAND RIDGE OVER THE WEEKEND...WHILE THE LATEST ECMWF RUN
INDICATES A WEAKER SURFACE LOW AND MORE PERSISTENT WEDGE ACROSS
THE MID ATLANTIC AND CAROLINAS. AS A RESULT...THE ECMWF KEEPS
CLOUDS AND SHOWERS IN THE FORECAST AREA THROUGH AT LEAST MONDAY
MORNING.
AT THIS POINT...HAVE NOT MADE SWEEPING CHANGES TO THE RAIN CHANCES
FROM THE PREVIOUS FORECAST UNTIL BETTER MODEL AGREEMENT. PREFER TO
FOCUS THE HIGHEST POPS SATURDAY NIGHT INTO SUNDAY...WHEN A WARM
FRONT/COASTAL FRONT COULD LIFT INTO SOUTHEAST SOUTH CAROLINA AND
SOUTHEAST GEORGIA AHEAD OF THE LOW SYSTEM. DESPITE DIFFERENCES IN THE
PATTERN EVOLUTION BETWEEN MEDIUM RANGE MODELS...THERE IS ENOUGH
AGREEMENT IN QPF FIELDS TO MAINTAIN LIKELY POPS FROM ABOUT 06Z
SUNDAY THROUGH 00Z MONDAY. DEPENDING ON HOW FAR THE WARM FRONT CAN
PENETRATE INTO THE FORECAST AREA...THERE IS ALSO A POTENTIAL FOR
THUNDER MAINLY ACROSS COASTAL SOUTH CAROLINA AND SOUTHEAST
GEORGIA.
A WEAK COLD FRONT WILL FOLLOW BEHIND THE LOW SYSTEM DEPARTING TO
THE NORTHEAST ON MONDAY. SURFACE HIGH PRESSURE WILL THEN BUILD
INTO THE AREA FROM THE WEST AND LIKELY BRING A PERIOD OF RAIN FREE
WEATHER FOR MUCH OF NEXT WEEK.
TEMPS WILL BE NEAR TO SLIGHTLY BELOW CLIMATOLOGICAL AVERAGES OVER
THE WEEKEND...WITH A SLIGHT WARMING TREND TOWARD THE LOW 70S EARLY
NEXT WEEK.
&&
.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
PINNING DOWN THE TIMING AND EXTENT OF FOG REMAINS THE MAIN
FORECAST CHALLENGE AT KCHS/KSAV FOR THE 06Z TAF CYCLE.
THE FOG IS INITIALLY SHALLOW AT 06Z AT KCHS...BUT WILL STEADILY
THICKEN THROUGH THE NIGHT AS SURFACE TEMPERATURES COOL INTO
THE LOWER 50S. THERE IS STILL SOME UNCERTAINTY ON EXACTLY HOW LOW
VSBYS WILL GET AS 1000MB GEOSTROPHIC WINDS ARE FORECAST TO
INCREASE AFTER 08Z. THIS MAY YIELD A BLENDED COMBINATION OF LOW
STRATUS AND FOG. CURRENT TRENDS SUGGEST THERE ARE REASONABLE
PROBABILITIES FOR AT LEAST PREVAILING IFR VSBYS AND THE LATEST
SHORT TERM GUIDANCE CONTINUES TO PAINT VSBYS AT KCHS WILL DROP TO
LESS THAN 1/4SM AFTER 08Z...MAYBE EVEN BRIEFLY AROUND DAWN AT
KSAV. WE ARE STILL NOT COMFORTABLE TO FORECAST VSBYS THAT LOW
GIVEN THE STRENGTH OF THE GEOSTROPHIC WINDS PROGGED LATER
TONIGHT...BUT HAVE MAINTAINED STRONG PERSISTENCE FROM THE 00Z
TAFS...SHOWING A TEMPO GROUP OF 1/2SM FG VV002 AT KCHS AND 3/4SM
BR SCT004 AT KSAV. ADDITIONAL ADJUSTMENTS WILL BE NEEDED AS FOG
TRENDS BECOME MORE APPARENT OVERNIGHT.
THE FOG SHOULD BURN OFF FAIRLY QUICKLY AFTER SUNRISE WITH
CONDITIONS RETURNING TO VFR AFTER 14-15Z...CONTINUING INTO
FRI EVENING.
EXTENDED AVIATION OUTLOOK...MVFR OR LOWER CEILINGS AND
VISIBILITIES POSSIBLE SAT AND SUNDAY. VFR THEREAFTER.
&&
.MARINE...
WE CONTINUE TO MONITOR TRENDS IN THE CHARLESTON HARBOR FOR A
POSSIBLE MARINE DENSE FOG ADVISORY. ATTM IT APPEARS THE RISK FOR
DENSE FOG WILL BE GREATEST FROM ROUGHLY 3 AM UNTIL 9 AM...HOWEVER
CONFIDENCE IN WIDESPREAD VISIBILITIES DROPPING TO LESS THAN 1 NM
ARE NOT HIGH ENOUGH JUST YET TO JUSTIFY RAISING AN ADVISORY. WILL
CONTINUE TO MENTION AREAS OF FOG WITH VISIBILITIES 2 NM OR LESS AT
TIMES. OTHERWISE EXPECT QUIET CONDITIONS TO PERSIST OVER THE
MARINE AREA. EXPECT WINDS TO PICK UP SOMEWHAT PRIOR TO SUNRISE AS
BOUNDARY LAYER WINDS. SPEEDS LOOK TO REMAIN LESS THAN 10 KT. SEAS
1-3 FT NEARSHORE WATERS AND 3-5 FT GEORGIA OFFSHORE WATERS.
AS SURFACE HIGH PRESSURE BUILDS EAST AND NORTHEAST TONIGHT THROUGH
FRIDAY...WINDS WILL REMAIN NORTHEASTERLY ACROSS THE WATERS. SPEEDS
WILL REMAIN BELOW 15 KT BUT SEAS WILL REMAIN AS HIGH AS 5 FT. WILL
HAVE TO WATCH TRENDS CAREFULLY FOR THE DEVELOPMENT OF FOG IN THE
CHARLESTON HARBOR LATER TONIGHT. A MARINE DENSE FOG ADVISORY MAY
EVENTUALLY BE NEEDED.
FRIDAY NIGHT THROUGH MONDAY...AN AREA OF LOW PRESSURE WILL
DEVELOP ACROSS THE NORTH-CENTRAL GULF OF MEXICO OVER THE
WEEKEND...WHILE SURFACE HIGH PRESSURE TO THE NORTH MAINTAINS AN
INLAND WEDGE. THIS AREA OF LOW PRESSURE WILL LIFT NORTHEAST AND
LIKELY PROGRESS ALONG THE GEORGIA/SOUTH CAROLINA COASTLINE SUNDAY
AND MONDAY. HIGH PRESSURE WILL THEN BUILD BACK INTO THE AREA NEXT
WEEK.
WINDS AND/OR SEAS COULD APPROACH SMALL CRAFT LEVELS ACROSS
PORTIONS OF THE WATERS SATURDAY NIGHT INTO SUNDAY NIGHT AS THE
AREA OF LOW PRESSURE MAKES ITS CLOSEST APPROACH. DUE TO SOME
UNCERTAINTIES BETWEEN FORECAST MODELS REGARDING THE STRENGTH AND
TRACK OF THE LOW SYSTEM...WILL KEEP WINDS AND SEAS BELOW SMALL
CRAFT THRESHOLDS THROUGH MONDAY AT THIS POINT.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...DENSE FOG ADVISORY UNTIL 9 AM EST THIS MORNING FOR SCZ043>045.
MARINE...NONE.
&&
$$
000
FXUS62 KCHS 200337 CCA
AFDCHS
AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE CHARLESTON SC
1036 PM EST THU NOV 19 2009
.SYNOPSIS...
WEAK HIGH PRESSURE WILL BUILD NORTH OF THE REGION TONIGHT THROUGH
FRIDAY. A GULF LOW PRESSURE SYSTEM WILL DEVELOP ON SATURDAY AND
POSSIBLY MOVE UP THE SOUTHEAST COAST SUNDAY INTO MONDAY. HIGH
PRESSURE WILL BUILD IN FROM THE WEST NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
VISIBILITIES ARE SLOWLY LOWERING ACROSS THE AREA THIS EVENING AS
TEMPERATURES APPROACH CROSS-OVER TEMPERATURES IN THE UPPER 50S.
CONDITIONS APPEAR FAVORABLE FOR FOG TO DEVELOP AS THE BOUNDARY
LAYER SATURATES AND THE NOCTURNAL INVERSION INTENSIFIES. 1000MB
GEOSTROPHIC WINDS ARE FORECAST TO INCREASE TO 15-20 KT SHORTLY
AFTER 5 AM...WHICH MAY TRANSITION SOME OF THE FOG INTO A VERY LOW
STRATUS DECK PRIOR TO SUNRISE. COMPLICATING MATTERS ARE THE HIGH
CLOUDS STREAMING IN FROM THE SOUTH ASSOCIATED WITH A MODEST
SUBTROPICAL JET. THESE CLOUDS ARE FORECAST REMAIN ACROSS MAINLY
THE CENTRAL/SOUTHERN PARTS OF THE FORECAST AREA AND WILL ALSO HELP
DELAY AND/OR LIMIT THE DENSE FOG POTENTIAL. PLAN TO STICK WITH
AREAS OF FOG FOR THESE AREAS BUT INCLUDE A MENTION OF PATCHY DENSE
FOG WITH VISIBILITIES OCCASIONALLY DROPPING BELOW 1/4 MILE AT
TIMES.
ACROSS THE FAR NORTH...THERE LOOKS TO A ENOUGH OF A POTENTIAL FOR
WIDESPREAD DENSE FOG TO DEVELOP MUCH OF BERKELEY/DORCHESTER AND
INLAND COLLETON COUNTIES TO JUSTIFY A DENSE FOG ADVISORY ATTM
SINCE THE BULK OF THE HIGH CLOUDS ARE PROGGED TO REMAIN TO THE
SOUTH. ALL AVAILABLE SHORT TERM GUIDANCE PACKAGES SUGGEST
WIDESPREAD VISIBILITIES OF 1/4 MILE OR LESS WILL DEVELOP SHORTLY
AFTER 1 AM AND CONSIDERING OBSERVATIONS OUT OF KINGSTREE HAVE BEEN
CONSISTENTLY 1/4 MILE OR LESS FOR THE PAST FEW HOURS...CONFIDENCE
IS INCREASING THAT ADVISORY LEVEL CONDITIONS WILL BE MET. WILL
KEEP THE ADVISORY OUT OF THE CHARLESTON METRO AREA FOR NOW...BUT
IT MAY VERY WELL HAVE TO BE EXPANDED TO INCLUDE ADJACENT COUNTIES
LATER TONIGHT. WILL RUN THE ADVISORY FROM 1 AM UNTIL 9 AM
FRIDAY...BUT THIS MAY HAVE TO BE ADJUSTED DEPENDING ON HOW THE
FOG REACTS TO INCREASING 1000MB GEOSTROPHIC WINDS PRIOR TO SUNRISE
FRIDAY.
WILL NUDGE OVERNIGHT LOWS UP A FEW DEGREES PER GOING TRENDS. EXPECT
LOWS FROM THE MID 40S FAR WEST INTERIOR TO THE UPPER 50S/NEAR 60
AT THE COAST.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
BROAD SOUTHWESTERLY FLOW WILL CONTINUE ALOFT ON FRIDAY WHILE
SURFACE HIGH PRESSURE CONTINUES TO BUILD NORTH OF THE REGION. WEAK
NVA AND SUBSIDENCE SHOULD PROVIDE FOR MOSTLY SUNNY SKIES MUCH OF
THE DAY. HOWEVER A NORTHERLY FLOW WILL KEEP HIGHS FROM RISING OUT
OF THE LOWER 70S.
&&
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
MAIN CONCERN DURING THE EXTENDED PERIOD WILL FALL BETWEEN SATURDAY
NIGHT AND MONDAY...AS AN UPPER SHORTWAVE DEVELOPS OVER THE GULF OF
MEXICO AND TRACKS NORTH/NORTHEAST THROUGH THE WEEKEND. AS THE
SURFACE REFLECTION OF THIS UPPER LOW TAKES SHAPE ALONG THE GULF
COAST STATES...HIGH PRESSURE TO THE NORTH OF THE FORECAST AREA
WILL MAINTAIN INLAND SURFACE RIDGING. MOST OF THE UNCERTAINTY
CONCERNING THE EVOLUTION OF THIS SYSTEM REVOLVES AROUND WHETHER
THE SURFACE LOW WILL BE STRONG ENOUGH TO PUSH THROUGH THE
WEDGE...OR REDEVELOP ALONG THE SOUTHEAST COAST.
THE STRONGER GFS SOLUTION INDICATES A SURFACE LOW PUNCHING INTO THE
INLAND RIDGE OVER THE WEEKEND...WHILE THE LATEST ECMWF RUN
INDICATES A WEAKER SURFACE LOW AND MORE PERSISTENT WEDGE ACROSS
THE MID ATLANTIC AND CAROLINAS. AS A RESULT...THE ECMWF KEEPS
CLOUDS AND SHOWERS IN THE FORECAST AREA THROUGH AT LEAST MONDAY
MORNING.
AT THIS POINT...HAVE NOT MADE SWEEPING CHANGES TO THE RAIN CHANCES
FROM THE PREVIOUS FORECAST UNTIL BETTER MODEL AGREEMENT. PREFER TO
FOCUS THE HIGHEST POPS SATURDAY NIGHT INTO SUNDAY...WHEN A WARM
FRONT/COASTAL FRONT COULD LIFT INTO SOUTHEAST SOUTH CAROLINA AND
SOUTHEAST GEORGIA AHEAD OF THE LOW SYSTEM. DESPITE DIFFERENCES IN THE
PATTERN EVOLUTION BETWEEN MEDIUM RANGE MODELS...THERE IS ENOUGH
AGREEMENT IN QPF FIELDS TO MAINTAIN LIKELY POPS FROM ABOUT 06Z
SUNDAY THROUGH 00Z MONDAY. DEPENDING ON HOW FAR THE WARM FRONT CAN
PENETRATE INTO THE FORECAST AREA...THERE IS ALSO A POTENTIAL FOR
THUNDER MAINLY ACROSS COASTAL SOUTH CAROLINA AND SOUTHEAST
GEORGIA.
A WEAK COLD FRONT WILL FOLLOW BEHIND THE LOW SYSTEM DEPARTING TO
THE NORTHEAST ON MONDAY. SURFACE HIGH PRESSURE WILL THEN BUILD
INTO THE AREA FROM THE WEST AND LIKELY BRING A PERIOD OF RAIN FREE
WEATHER FOR MUCH OF NEXT WEEK.
TEMPS WILL BE NEAR TO SLIGHTLY BELOW CLIMATOLOGICAL AVERAGES OVER
THE WEEKEND...WITH A SLIGHT WARMING TREND TOWARD THE LOW 70S EARLY
NEXT WEEK.
&&
.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
PINNING DOWN THE TIMING AND EXTENT OF FOG IS THE MAIN FORECAST
CHALLENGE AT KCHS/KSAV FOR THE NEXT 12 HOURS. CONDITIONS WILL
FAVOR FOG DEVELOPMENT OVER THE NEXT SEVERAL HOURS AS SURFACE
TEMPERATURES DROP INTO THE 50S AND THE BOUNDARY LAYER SATURATES.
CROSS OVER TEMPERATURES ARE IN THE UPPER 50S AND SOME FOG IS
ALREADY DEVELOPING NORTH OF KCHS WHERE VSBYS HAVE BEEN AS LOW AS
1/4SM AT KCKI AND 3SM AT KMKS AS OF 2330Z.
THE FOG WILL INITIALLY BE SHALLOW BUT WILL STEADILY THICKEN
THROUGH THE NIGHT AS SURFACE TEMPERATURES COOL. THERE IS STILL
SOME UNCERTAINTY ON EXACTLY HOW LOW VSBYS WILL GET AS 1000MB
GEOSTROPHIC WINDS ARE FORECAST TO INCREASE AFTER 08Z. THIS MAY
VERY WELL YIELD A BLENDED COMBINATION OF LOW STRATUS AND FOG.
CURRENT TRENDS SUGGEST THERE ARE REASONABLE PROBABILITIES FOR AT
LEAST PREVAILING IFR VSBYS AND THE LATEST SHORT TERM GUIDANCE
SUGGEST VSBYS AT BOTH SITES WILL DROP TO LESS THAN 1/4SM AFTER
08Z. WE ARE NOT QUITE READY TO FORECAST VSBYS THAT LOW GIVEN THE
STRENGTH OF THE GEOSTROPHIC WINDS PROGGED LATER TONIGHT...BUT WILL
CERTAINLY TREND VSBYS DOWN FROM THE 18Z TAFS...SHOWING A TEMPO
GROUP OF 1/2SM FG VV002 AT KCHS AND 3/4SM BR SCT004 AT KSAV.
ADDITIONAL ADJUSTMENTS WILL BE NEEDED AS FOG TRENDS BECOME MORE
APPARENT LATER THIS EVENING AND OVERNIGHT.
THE FOG SHOULD BURN OFF FAIRLY QUICKLY AFTER SUNRISE WITH
CONDITIONS RETURNING TO VFR AFTER 14-15Z.
EXTENDED AVIATION OUTLOOK...MVFR OR LOWER CEILINGS AND
VISIBILITIES POSSIBLE SATURDAY AND SUNDAY. VFR THEREAFTER.
&&
.MARINE...
WE CONTINUE TO MONITOR TRENDS IN THE CHARLESTON HARBOR FOR A
POSSIBLE MARINE DENSE FOG ADVISORY. ATTM IT APPEARS THE RISK FOR
DENSE FOG WILL BE GREATEST FROM ROUGHLY 3 AM UNTIL 9 AM...HOWEVER
CONFIDENCE IN WIDESPREAD VISIBILITIES DROPPING TO LESS THAN 1 NM
ARE NOT HIGH ENOUGH JUST YET TO JUSTIFY RAISING AN ADVISORY. WILL
CONTINUE TO MENTION AREAS OF FOG WITH VISIBILITIES 2 NM OR LESS AT
TIMES. OTHERWISE EXPECT QUIET CONDITIONS TO PERSIST OVER THE
MARINE AREA. EXPECT WINDS TO PICK UP SOMEWHAT PRIOR TO SUNRISE AS
BOUNDARY LAYER WINDS. SPEEDS LOOK TO REMAIN LESS THAN 10 KT. SEAS
1-3 FT NEARSHORE WATERS AND 3-5 FT GEORGIA OFFSHORE WATERS.
AS SURFACE HIGH PRESSURE BUILDS EAST AND NORTHEAST TONIGHT THROUGH
FRIDAY...WINDS WILL REMAIN NORTHEASTERLY ACROSS THE WATERS. SPEEDS
WILL REMAIN BELOW 15 KT BUT SEAS WILL REMAIN AS HIGH AS 5 FT. WILL
HAVE TO WATCH TRENDS CAREFULLY FOR THE DEVELOPMENT OF FOG IN THE
CHARLESTON HARBOR LATER TONIGHT. A MARINE DENSE FOG ADVISORY MAY
EVENTUALLY BE NEEDED.
FRIDAY NIGHT THROUGH MONDAY...AN AREA OF LOW PRESSURE WILL
DEVELOP ACROSS THE NORTH-CENTRAL GULF OF MEXICO OVER THE
WEEKEND...WHILE SURFACE HIGH PRESSURE TO THE NORTH MAINTAINS AN
INLAND WEDGE. THIS AREA OF LOW PRESSURE WILL LIFT NORTHEAST AND
LIKELY PROGRESS ALONG THE GEORGIA/SOUTH CAROLINA COASTLINE SUNDAY
AND MONDAY. HIGH PRESSURE WILL THEN BUILD BACK INTO THE AREA NEXT
WEEK.
WINDS AND/OR SEAS COULD APPROACH SMALL CRAFT LEVELS ACROSS
PORTIONS OF THE WATERS SATURDAY NIGHT INTO SUNDAY NIGHT AS THE
AREA OF LOW PRESSURE MAKES ITS CLOSEST APPROACH. DUE TO SOME
UNCERTAINTIES BETWEEN FORECAST MODELS REGARDING THE STRENGTH AND
TRACK OF THE LOW SYSTEM...WILL KEEP WINDS AND SEAS BELOW SMALL
CRAFT THRESHOLDS THROUGH MONDAY AT THIS POINT.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...DENSE FOG ADVISORY UNTIL 9 AM EST FRIDAY FOR SCZ043>045.
MARINE...NONE.
&&
$$
000
FXUS62 KCHS 200336
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
1036 PM EST THU NOV 19 2009
.SYNOPSIS...
WEAK HIGH PRESSURE WILL BUILD NORTH OF THE REGION TONIGHT THROUGH
FRIDAY. A GULF LOW PRESSURE SYSTEM WILL DEVELOP ON SATURDAY AND
POSSIBLY MOVE UP THE SOUTHEAST COAST SUNDAY INTO MONDAY. HIGH
PRESSURE WILL BUILD IN FROM THE WEST NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
VISIBILITIES ARE SLOWLY LOWERING ACROSS THE AREA THIS EVENING AS
TEMPERATURES APPROACH CROSS-OVER TEMPERATURES IN THE UPPER 50S.
CONDITIONS APPEAR FAVORABLE FOR FOG TO DEVELOP AS THE BOUNDARY
LAYER SATURATES AND THE NOCTURNAL INVERSION INTENSIFIES. 1000MB
GEOSTROPHIC WINDS ARE FORECAST TO INCREASE TO 15-20 KT SHORTLY
AFTER 5 AM...WHICH MAY TRANSITION SOME OF THE FOG INTO A VERY LOW
STRATUS DECK PRIOR TO SUNRISE. COMPLICATING MATTERS ARE THE HIGH
CLOUDS STREAMING IN FROM THE SOUTH ASSOCIATED WITH A MODEST
SUBTROPICAL JET. THESE CLOUDS ARE FORECAST REMAIN ACROSS MAINLY
THE CENTRAL/SOUTHERN PARTS OF THE FORECAST AREA AND WILL ALSO HELP
DELAY AND/OR LIMIT THE DENSE FOG POTENTIAL. PLAN TO STICK WITH
AREAS OF FOG FOR THESE AREAS BUT INCLUDE A MENTION OF PATCHY DENSE
FOG WITH VISIBILITIES OCCASIONALLY DROPPING BELOW 1/4 MILE AT
TIMES.
ACROSS THE FAR NORTH...THERE LOOKS TO A ENOUGH OF A POTENTIAL FOR
WIDESPREAD DENSE FOG TO DEVELOP MUCH OF BERKELEY/DORCHESTER AND
INLAND COLLETON COUNTIES TO JUSTIFY A DENSE FOG ADVISORY ATTM
SINCE THE BULK OF THE HIGH CLOUDS ARE PROGGED TO REMAIN TO THE
SOUTH. ALL AVAILABLE SHORT TERM GUIDANCE PACKAGES SUGGEST
WIDESPREAD VISIBILITIES OF 1/4 MILE OR LESS WILL DEVELOP SHORTLY
AFTER 1 AM AND CONSIDERING OBSERVATIONS OUT OF KINGSTREE HAVE BEEN
CONSISTENTLY 1/4 MILE OR LESS FOR THE PAST FEW HOURS...CONFIDENCE
IS INCREASING THAT ADVISORY LEVEL CONDITIONS WILL BE MET. WILL
KEEP THE ADVISORY OUT OF THE CHARLESTON METRO AREA FOR NOW...BUT
IT MAY VERY WELL HAVE TO BE EXPANDED TO INCLUDE ADJACENT COUNTIES
LATER TONIGHT. WILL RUN THE ADVISORY FROM 1 AM UNTIL 9 AM
WEDNESDAY...BUT THIS MAY HAVE TO BE ADJUSTED DEPENDING ON HOW THE
FOG REACTS TO INCREASING 1000MB GEOSTROPHIC WINDS PRIOR TO SUNRISE
FRIDAY.
WILL NUDGE OVERNIGHT LOWS UP A FEW DEGREES PER GOING TRENDS. EXPECT
LOWS FROM THE MID 40S FAR WEST INTERIOR TO THE UPPER 50S/NEAR 60
AT THE COAST.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
BROAD SOUTHWESTERLY FLOW WILL CONTINUE ALOFT ON FRIDAY WHILE
SURFACE HIGH PRESSURE CONTINUES TO BUILD NORTH OF THE REGION. WEAK
NVA AND SUBSIDENCE SHOULD PROVIDE FOR MOSTLY SUNNY SKIES MUCH OF
THE DAY. HOWEVER A NORTHERLY FLOW WILL KEEP HIGHS FROM RISING OUT
OF THE LOWER 70S.
&&
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
MAIN CONCERN DURING THE EXTENDED PERIOD WILL FALL BETWEEN SATURDAY
NIGHT AND MONDAY...AS AN UPPER SHORTWAVE DEVELOPS OVER THE GULF OF
MEXICO AND TRACKS NORTH/NORTHEAST THROUGH THE WEEKEND. AS THE
SURFACE REFLECTION OF THIS UPPER LOW TAKES SHAPE ALONG THE GULF
COAST STATES...HIGH PRESSURE TO THE NORTH OF THE FORECAST AREA
WILL MAINTAIN INLAND SURFACE RIDGING. MOST OF THE UNCERTAINTY
CONCERNING THE EVOLUTION OF THIS SYSTEM REVOLVES AROUND WHETHER
THE SURFACE LOW WILL BE STRONG ENOUGH TO PUSH THROUGH THE
WEDGE...OR REDEVELOP ALONG THE SOUTHEAST COAST.
THE STRONGER GFS SOLUTION INDICATES A SURFACE LOW PUNCHING INTO THE
INLAND RIDGE OVER THE WEEKEND...WHILE THE LATEST ECMWF RUN
INDICATES A WEAKER SURFACE LOW AND MORE PERSISTENT WEDGE ACROSS
THE MID ATLANTIC AND CAROLINAS. AS A RESULT...THE ECMWF KEEPS
CLOUDS AND SHOWERS IN THE FORECAST AREA THROUGH AT LEAST MONDAY
MORNING.
AT THIS POINT...HAVE NOT MADE SWEEPING CHANGES TO THE RAIN CHANCES
FROM THE PREVIOUS FORECAST UNTIL BETTER MODEL AGREEMENT. PREFER TO
FOCUS THE HIGHEST POPS SATURDAY NIGHT INTO SUNDAY...WHEN A WARM
FRONT/COASTAL FRONT COULD LIFT INTO SOUTHEAST SOUTH CAROLINA AND
SOUTHEAST GEORGIA AHEAD OF THE LOW SYSTEM. DESPITE DIFFERENCES IN THE
PATTERN EVOLUTION BETWEEN MEDIUM RANGE MODELS...THERE IS ENOUGH
AGREEMENT IN QPF FIELDS TO MAINTAIN LIKELY POPS FROM ABOUT 06Z
SUNDAY THROUGH 00Z MONDAY. DEPENDING ON HOW FAR THE WARM FRONT CAN
PENETRATE INTO THE FORECAST AREA...THERE IS ALSO A POTENTIAL FOR
THUNDER MAINLY ACROSS COASTAL SOUTH CAROLINA AND SOUTHEAST
GEORGIA.
A WEAK COLD FRONT WILL FOLLOW BEHIND THE LOW SYSTEM DEPARTING TO
THE NORTHEAST ON MONDAY. SURFACE HIGH PRESSURE WILL THEN BUILD
INTO THE AREA FROM THE WEST AND LIKELY BRING A PERIOD OF RAIN FREE
WEATHER FOR MUCH OF NEXT WEEK.
TEMPS WILL BE NEAR TO SLIGHTLY BELOW CLIMATOLOGICAL AVERAGES OVER
THE WEEKEND...WITH A SLIGHT WARMING TREND TOWARD THE LOW 70S EARLY
NEXT WEEK.
&&
.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
PINNING DOWN THE TIMING AND EXTENT OF FOG IS THE MAIN FORECAST
CHALLENGE AT KCHS/KSAV FOR THE NEXT 12 HOURS. CONDITIONS WILL
FAVOR FOG DEVELOPMENT OVER THE NEXT SEVERAL HOURS AS SURFACE
TEMPERATURES DROP INTO THE 50S AND THE BOUNDARY LAYER SATURATES.
CROSS OVER TEMPERATURES ARE IN THE UPPER 50S AND SOME FOG IS
ALREADY DEVELOPING NORTH OF KCHS WHERE VSBYS HAVE BEEN AS LOW AS
1/4SM AT KCKI AND 3SM AT KMKS AS OF 2330Z.
THE FOG WILL INITIALLY BE SHALLOW BUT WILL STEADILY THICKEN
THROUGH THE NIGHT AS SURFACE TEMPERATURES COOL. THERE IS STILL
SOME UNCERTAINTY ON EXACTLY HOW LOW VSBYS WILL GET AS 1000MB
GEOSTROPHIC WINDS ARE FORECAST TO INCREASE AFTER 08Z. THIS MAY
VERY WELL YIELD A BLENDED COMBINATION OF LOW STRATUS AND FOG.
CURRENT TRENDS SUGGEST THERE ARE REASONABLE PROBABILITIES FOR AT
LEAST PREVAILING IFR VSBYS AND THE LATEST SHORT TERM GUIDANCE
SUGGEST VSBYS AT BOTH SITES WILL DROP TO LESS THAN 1/4SM AFTER
08Z. WE ARE NOT QUITE READY TO FORECAST VSBYS THAT LOW GIVEN THE
STRENGTH OF THE GEOSTROPHIC WINDS PROGGED LATER TONIGHT...BUT WILL
CERTAINLY TREND VSBYS DOWN FROM THE 18Z TAFS...SHOWING A TEMPO
GROUP OF 1/2SM FG VV002 AT KCHS AND 3/4SM BR SCT004 AT KSAV.
ADDITIONAL ADJUSTMENTS WILL BE NEEDED AS FOG TRENDS BECOME MORE
APPARENT LATER THIS EVENING AND OVERNIGHT.
THE FOG SHOULD BURN OFF FAIRLY QUICKLY AFTER SUNRISE WITH
CONDITIONS RETURNING TO VFR AFTER 14-15Z.
EXTENDED AVIATION OUTLOOK...MVFR OR LOWER CEILINGS AND
VISIBILITIES POSSIBLE SATURDAY AND SUNDAY. VFR THEREAFTER.
&&
.MARINE...
WE CONTINUE TO MONITOR TRENDS IN THE CHARLESTON HARBOR FOR A
POSSIBLE MARINE DENSE FOG ADVISORY. ATTM IT APPEARS THE RISK FOR
DENSE FOG WILL BE GREATEST FROM ROUGHLY 3 AM UNTIL 9 AM...HOWEVER
CONFIDENCE IN WIDESPREAD VISIBILITIES DROPPING TO LESS THAN 1 NM
ARE NOT HIGH ENOUGH JUST YET TO JUSTIFY RAISING AN ADVISORY. WILL
CONTINUE TO MENTION AREAS OF FOG WITH VISIBILITIES 2 NM OR LESS AT
TIMES. OTHERWISE EXPECT QUIET CONDITIONS TO PERSIST OVER THE
MARINE AREA. EXPECT WINDS TO PICK UP SOMEWHAT PRIOR TO SUNRISE AS
BOUNDARY LAYER WINDS. SPEEDS LOOK TO REMAIN LESS THAN 10 KT. SEAS
1-3 FT NEARSHORE WATERS AND 3-5 FT GEORGIA OFFSHORE WATERS.
AS SURFACE HIGH PRESSURE BUILDS EAST AND NORTHEAST TONIGHT THROUGH
FRIDAY...WINDS WILL REMAIN NORTHEASTERLY ACROSS THE WATERS. SPEEDS
WILL REMAIN BELOW 15 KT BUT SEAS WILL REMAIN AS HIGH AS 5 FT. WILL
HAVE TO WATCH TRENDS CAREFULLY FOR THE DEVELOPMENT OF FOG IN THE
CHARLESTON HARBOR LATER TONIGHT. A MARINE DENSE FOG ADVISORY MAY
EVENTUALLY BE NEEDED.
FRIDAY NIGHT THROUGH MONDAY...AN AREA OF LOW PRESSURE WILL
DEVELOP ACROSS THE NORTH-CENTRAL GULF OF MEXICO OVER THE
WEEKEND...WHILE SURFACE HIGH PRESSURE TO THE NORTH MAINTAINS AN
INLAND WEDGE. THIS AREA OF LOW PRESSURE WILL LIFT NORTHEAST AND
LIKELY PROGRESS ALONG THE GEORGIA/SOUTH CAROLINA COASTLINE SUNDAY
AND MONDAY. HIGH PRESSURE WILL THEN BUILD BACK INTO THE AREA NEXT
WEEK.
WINDS AND/OR SEAS COULD APPROACH SMALL CRAFT LEVELS ACROSS
PORTIONS OF THE WATERS SATURDAY NIGHT INTO SUNDAY NIGHT AS THE
AREA OF LOW PRESSURE MAKES ITS CLOSEST APPROACH. DUE TO SOME
UNCERTAINTIES BETWEEN FORECAST MODELS REGARDING THE STRENGTH AND
TRACK OF THE LOW SYSTEM...WILL KEEP WINDS AND SEAS BELOW SMALL
CRAFT THRESHOLDS THROUGH MONDAY AT THIS POINT.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...DENSE FOG ADVISORY UNTIL 9 AM EST FRIDAY FOR SCZ043>045.
MARINE...NONE.
&&
$$
000
FXUS62 KFFC 200237 AAA
AFDFFC
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
930 PM EST THU NOV 19 2009
.UPDATE...
ONLY MINOR UPDATES BEING MADE THIS EVENING. MIN TEMPS LOOKED A TAD
TOO WARM IN THE AHN AREA...SO LOWERED A COUPLE OF DEGREES THERE
BASED ON LATEST MET GUIDANCE. INCREASED CLOUD COVER SLIGHTLY
OVERNIGHT AS PATCHES OF CIRRUS DRIFTING ACROSS WITH WSW FLOW ALOFT.
ALSO INCREASED CLOUD COVER LATE FRI-SAT SINCE LATEST MODEL RUNS
SHOWING NEAR SATURATION IN THE HIGHER LAYERS BY 00Z SAT AS DENSE
CIRRUS SHIELD SPREADS ACROSS IN ADVANCE OF RAPIDLY DEVELOPING SHORT
WAVE MOVING NE FROM THE WESTERN GULF. GFS CONSIDERABLY
STRONGER...AND WITH A GREATER NEGATIVE TILT...WITH NEXT SHORT WAVE
THAN ECMWF...AND THIS WILL PLAY A BIG PART IN HOW MUCH RAIN AND
POTENTIAL TSRA ACTIVITY WE GET LATE SAT-SUN. MAV TSRA POPS
SUGGESTING THAT TSRA MAY NEED TO BE ADDED FOR CENTRAL ZONES SAT
NIGHT/EARLY SUN. WITH SOME INSTABILITY AND CONSIDERABLE SHEAR...TSRA
THREAT WILL NEED TO BE WATCHED CAREFULLY BY LATER SHIFTS. QPF WILL
ALSO NEED TO BE WATCHED. GFS SHOWING 1.5-2.0 INCHES...WITH ECMWF
SHOWING GENERALLY 0.25-0.50 INCH ACROSS OUR CWA. MUCH MORE THAN 2.0
INCHES OF RAIN WILL LIKELY RESULT IN RENEWED RIVER FLOODING.
19
&&
.PREVIOUS FORECAST DISCUSSION ISSUED 0520 PM EST...
.SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/...
SURFACE HIGH PRESSURE WILL CONTINUE TO BUILD ACROSS THE SOUTHEAST
BEHIND THE WEAK FRONTAL BOUNDARY CURRENTLY PUSHING INTO THE
CAROLINAS. DRY CONDITIONS WILL PREVAIL THROUGH FRIDAY...THEN
MOISTURE ASSOCIATED WITH OUR NEXT SYSTEM WILL SPREAD ACROSS THE
STATE SATURDAY. CLEAR CONDITIONS AND LITTLE WIND OVERNIGHT TONIGHT
WILL PROMOTE AREAS OF FROST FRIDAY MORNING...MAINLY ACROSS NORTHWEST
AND PORTIONS OF WEST CENTRAL GEORGIA. OUR CUT OFF DATE FOR FROST
ADVISORIES IS NOVEMBER 20...SO NO ADVISORY WILL BE ISSUED. THE U.S.
DEPT OF AGRICULTURE INDICATED THAT THE SEASON HAS COME TO AN END FOR
SUMMER CROPS...AND FALL CROPS SHOULD BE ABLE TO WITHSTAND FROST
CONDITIONS. IT WAS FURTHER INDICATED THAT OUR OFFICE POLICY SHOULD
NOT BE AMENDED FOR THIS ONE INSTANCE. PRECAUTIONARY MEASURES CAN
STILL BE TAKEN FOR THOSE CONCERNED ABOUT SENSITIVE OUTDOOR PLANTS.
MODELS IN AGREEMENT WITH DEVELOPING LOW PRESSURE OVER TEXAS...WITH
THE SURFACE LOW CENTERED OVER THE NW GULF. AS THE LOW MOVES
NORTHEASTWARD OVER THE SOUTHEAST...MOISTURE WILL BEGIN SPREADING
ACROSS THE STATE. HAVE CONTINUED CHANCE POPS FOR WEST CENTRAL GA
SATURDAY MORNING...INCREASING TO LIKELY POPS...AND THEN CATEGORICAL
THROUGH SATURDAY NIGHT. ALTHOUGH MODELS SHOW GOOD SHEAR SATURDAY...
BEST CAPE AND LI VALUES ARE OVER SOUTHEAST GA SUNDAY. FOR NOW HAVE
NOT INDICATED THUNDER IN THE FORECAST...BUT THIS MAY NEED AMENDING
AS WE GET CLOSER...ESPECIALLY OVER THE SOUTHERN MOST TIERS OF OUR
CWA.
GENERALLY USED A BLEND OF MAV/MET GUIDANCE FOR TEMPERATURES THROUGH
THE SHORT TERM. WITH MORE CLOUDS OVER THE AREA SATURDAY AND
SUNDAY...LOW TEMPERATURES WILL BE WARMER THAN FRIDAY...ALTHOUGH
GUIDANCE SEEMS TO BE TOO WARM. HAVE ERRED ON THE COOL SIDE OF THE
MAV/MET BLEND FOR HIGHS AND LOWS SATURDAY.
.LONG TERM /SUNDAY THROUGH THURSDAY/...
ECMWF PULLS THE SURFACE LOW ACROSS SOUTHERN GA...WITH IT POSITIONED
OVER THE CAROLINA COAST BY MONDAY EVENING. NAM AND GFS MORE IN LINE
WITH KEEPING THE LOW MORE VERTICALLY STACKED...AND MOVING THE OHIO
RIVER VALLEY BY SUNDAY EVENING. FOR NOW...HAVE LEANED MORE TOWARDS
THE ECMWF...WHICH IS CONSISTENT WITH THE HPC QPF...WITH CATEGORICAL
POPS FOR MOST OF NORTH AND CENTRAL GA EARLY SUNDAY. HAVE DECREASED
POPS WEST TO EAST THROUGH SUNDAY...WITH ONLY CHANCE POPS IN FOR
SUNDAY EVENING AS THE SYSTEM CONTINUES TO MOVE OVER THE CAROLINAS.
TOTAL QPF FOR THE EVENT SHOULD GENERALLY BE IN THE 1 TO 2 INCH
RANGE...WITH THE HEAVIEST AMOUNTS OVER SOUTH AND CENTRAL GEORGIA.
ECMWF AND GFS KEEP GEORGIA IN WEST TO NORTHWEST UPPER FLOW THROUGH
THE EXTENDED...WITH MULTIPLE FRONTAL BOUNDARIES MOVING THROUGH. AT
THIS POINT MODELS SHOW THE COLD FRONTS TO BE MAINLY DRY...SO HAVE
CONTINUED WITH PREVIOUS FORECAST INDICATING DRY AND COOL CONDITIONS
THROUGH MOST OF THE WEEK.
31
&&
.AVIATION...
VFR THROUGH THE FORECAST ALL SITES...SOME LIGHT FOG IS POSSIBLE IN
THE AHN/MCN AREAS LATE TONIGHT. WINDS WILL SLOWLY SHIFT TO THE
NORTHEAST BETWEEN 12Z AND 18Z FRIDAY ALL SITES.
17
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 42 67 43 62 47 / 0 0 10 40 80
ATLANTA 40 66 44 59 47 / 0 0 10 50 80
BLAIRSVILLE 36 64 37 59 43 / 0 0 10 30 70
CARTERSVILLE 34 66 39 61 47 / 0 0 10 50 80
COLUMBUS 40 70 49 64 53 / 0 0 10 70 80
GAINESVILLE 42 64 44 60 46 / 0 0 10 40 80
MACON 38 70 49 64 53 / 0 0 10 50 80
ROME 35 66 39 62 49 / 0 0 10 40 70
PEACHTREE CITY 32 67 39 59 49 / 0 0 10 50 80
VIDALIA 45 74 50 65 52 / 0 0 10 30 70
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
31/17/19
000
FXUS62 KCAE 200222
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
922 PM EST THU NOV 19 2009
.SYNOPSIS...
HIGH PRESSURE WILL MOVE INTO THE AREA AND DOMINATE TONIGHT THROUGH
EARLY SATURDAY. A LOW PRESSURE SYSTEM WILL MOVE OUT OF THE GULF OF
MEXICO AND BRING RAIN TO THE AREA SATURDAY NIGHT THROUGH SUNDAY.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
HIGH PRESSURE CONTINUES TO ENTER THE FORECAST AREA WITH ADDITIONAL
DRYING SLOWLY MOVING THROUGH CENTRAL AND EASTERN GA. ACARS
SOUNDINGS INDICATE INVERSION ALREADY DEVELOPING WITH THE NORTHERN
MIDLANDS SEEING SOME DEVELOPING FOG. WILL KEEP AREAS OF FOG IN THE
FORECAST THROUGH THE NIGHT...HOWEVER WITH THE DRIER AIR AND LITTLE
AVAILABLE MOISTURE ON THE GROUND WILL HOLD OFF ON ISSUING ANY
DENSE FOG PRODUCTS ATTM. WILL ISSUE AN UPDATE TO ADJUST WORDING
AND TWEAK TEMPERATURES.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY/...
THE NAM AND GFS SHOW DRY RIDGING DOMINATING FRIDAY THROUGH EARLY
SATURDAY. ISENTROPIC LIFT WILL BE ON THE INCREASE SATURDAY AHEAD
OF LOW PRESSURE APPROACHING FROM THE GULF OF MEXICO. THE MAV AND
MET MOS ARE IN GOOD AGREEMENT SHOWING CHANCE POPS IN THE SOUTHWEST
SECTION TO SLIGHT CHANCE POPS IN THE NORTHEAST PART SATURDAY
AFTERNOON. USED THE GUIDANCE CONSENSUS FOR THE TEMPERATURE
FORECAST EXCEPT THE COOLER VALUES APPEARED BETTER SATURDAY BECAUSE
OF EXPECTED CLOUDINESS.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
THE GFS AND ECMWF SHOW HIGH MOISTURE SUNDAY ASSOCIATED WITH LOW
PRESSURE MOVING THROUGH THE AREA. THE MODELS SHOW A DRY PATTERN
DURING THE REST OF THE PERIOD. THE GFS ENSEMBLES INDICATE SEASONABLE
TEMPERATURES.
&&
.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
VFR CONDITIONS WILL CONTINUE THROUGH THE EVENING. CONTINUED HIGH
LOW-LEVEL MOISTURE PLUS DIURNAL COOLING SHOULD RESULT IN IFR FOG
DEVELOPMENT LATE TONIGHT AT AGS AND OGB. LOW END MVFR VISIBILITIES
POSSIBLE LATE TONIGHT AT CAE/CUB/DNL. NAM IS MUCH MORE
PESSIMISTIC...BUT I LEANED MORE TOWARDS THE MAV GUIDANCE THIS RUN.
AFTER SUNRISE FRIDAY...HEATING AND MIXING SHOULD RESULT IN A RETURN
TO VFR CONDITIONS AROUND 14Z AT ALL SITES.
EXTENDED AVIATION OUTLOOK...WIDESPREAD MVFR OR IFR CONDITIONS WILL
LIKELY OCCUR 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.
&&
$$
000
FXUS62 KCHS 192339
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
639 PM EST THU NOV 19 2009
.SYNOPSIS...
WEAK HIGH PRESSURE WILL BUILD NORTH OF THE REGION TONIGHT THROUGH
FRIDAY. A GULF LOW PRESSURE SYSTEM WILL DEVELOP ON SATURDAY AND
POSSIBLY MOVE UP THE SOUTHEAST COAST SUNDAY INTO MONDAY. HIGH
PRESSURE WILL BUILD IN FROM THE WEST NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
WE CONTINUE TO EVALUATE THE POTENTIAL FOR DENSE FOG FOR TONIGHT.
ALREADY STARTING TO SEE SOME SHALLOW GROUND FOG DEVELOP ACROSS
PARTS OF THE CHARLESTON TRI-COUNTY AREA WHERE SEVERAL AUTOMATED
OBSERVATION SITES WERE REPORTING VISIBILITIES LESS THAN 4 MILES AT
6 PM. THERE IS STILL A QUESTION ON HOW DENSE THE FOG WILL BECOME
AS GEOSTROPHIC WINDS ARE FORECAST TO INCREASE AFTER 3 AM WHEN
CONDITIONS WILL BE THE MOST FAVORABLE FOR DENSE FOG FORMATION.
WILL CONTINUE WITH AREAS OF FOG FOR ALL AREAS TONIGHT...BUT WITH
INCOMING SHORT TERM MODEL GUIDANCE CONTINUING TO TREND TOWARDS A
MORE PESSIMISTIC FOG FORECAST...WILL UPDATE THE HAZARDOUS WEATHER
OUTLOOK TO INCLUDE A MENTION THAT A DENSE FOG ADVISORY MAY
EVENTUALLY BE NEEDED FOR ALL OR PARTS OF THE AREA...INCLUDING
CHARLESTON HARBOR.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
BROAD SOUTHWESTERLY FLOW WILL CONTINUE ALOFT ON FRIDAY WHILE
SURFACE HIGH PRESSURE CONTINUES TO BUILD NORTH OF THE REGION. WEAK
NVA AND SUBSIDENCE SHOULD PROVIDE FOR MOSTLY SUNNY SKIES MUCH OF
THE DAY. HOWEVER A NORTHERLY FLOW WILL KEEP HIGHS FROM RISING OUT
OF THE LOWER 70S.
&&
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
MAIN CONCERN DURING THE EXTENDED PERIOD WILL FALL BETWEEN SATURDAY
NIGHT AND MONDAY...AS AN UPPER SHORTWAVE DEVELOPS OVER THE GULF OF
MEXICO AND TRACKS NORTH/NORTHEAST THROUGH THE WEEKEND. AS THE
SURFACE REFLECTION OF THIS UPPER LOW TAKES SHAPE ALONG THE GULF
COAST STATES...HIGH PRESSURE TO THE NORTH OF THE FORECAST AREA
WILL MAINTAIN INLAND SURFACE RIDGING. MOST OF THE UNCERTAINTY
CONCERNING THE EVOLUTION OF THIS SYSTEM REVOLVES AROUND WHETHER
THE SURFACE LOW WILL BE STRONG ENOUGH TO PUSH THROUGH THE
WEDGE...OR REDEVELOP ALONG THE SOUTHEAST COAST.
THE STRONGER GFS SOLUTION INDICATES A SURFACE LOW PUNCHING INTO THE
INLAND RIDGE OVER THE WEEKEND...WHILE THE LATEST ECMWF RUN
INDICATES A WEAKER SURFACE LOW AND MORE PERSISTENT WEDGE ACROSS
THE MID ATLANTIC AND CAROLINAS. AS A RESULT...THE ECMWF KEEPS
CLOUDS AND SHOWERS IN THE FORECAST AREA THROUGH AT LEAST MONDAY
MORNING.
AT THIS POINT...HAVE NOT MADE SWEEPING CHANGES TO THE RAIN CHANCES
FROM THE PREVIOUS FORECAST UNTIL BETTER MODEL AGREEMENT. PREFER TO
FOCUS THE HIGHEST POPS SATURDAY NIGHT INTO SUNDAY...WHEN A WARM
FRONT/COASTAL FRONT COULD LIFT INTO SOUTHEAST SOUTH CAROLINA AND
SOUTHEAST GEORGIA AHEAD OF THE LOW SYSTEM. DESPITE DIFFERENCES IN THE
PATTERN EVOLUTION BETWEEN MEDIUM RANGE MODELS...THERE IS ENOUGH
AGREEMENT IN QPF FIELDS TO MAINTAIN LIKELY POPS FROM ABOUT 06Z
SUNDAY THROUGH 00Z MONDAY. DEPENDING ON HOW FAR THE WARM FRONT CAN
PENETRATE INTO THE FORECAST AREA...THERE IS ALSO A POTENTIAL FOR
THUNDER MAINLY ACROSS COASTAL SOUTH CAROLINA AND SOUTHEAST
GEORGIA.
A WEAK COLD FRONT WILL FOLLOW BEHIND THE LOW SYSTEM DEPARTING TO
THE NORTHEAST ON MONDAY. SURFACE HIGH PRESSURE WILL THEN BUILD
INTO THE AREA FROM THE WEST AND LIKELY BRING A PERIOD OF RAIN FREE
WEATHER FOR MUCH OF NEXT WEEK.
TEMPS WILL BE NEAR TO SLIGHTLY BELOW CLIMATOLOGICAL AVERAGES OVER
THE WEEKEND...WITH A SLIGHT WARMING TREND TOWARD THE LOW 70S EARLY
NEXT WEEK.
&&
.AVIATION /23Z THURSDAY THROUGH TUESDAY/...
PINNING DOWN THE TIMING AND EXTENT OF FOG IS THE MAIN FORECAST
CHALLENGE AT KCHS/KSAV FOR THE NEXT 12 HOURS. CONDITIONS WILL
FAVOR FOG DEVELOPMENT OVER THE NEXT SEVERAL HOURS AS SURFACE
TEMPERATURES DROP INTO THE 50S AND THE BOUNDARY LAYER SATURATES.
CROSS OVER TEMPERATURES ARE IN THE UPPER 50S AND SOME FOG IS
ALREADY DEVELOPING NORTH OF KCHS WHERE VSBYS HAVE BEEN AS LOW AS
1/4SM AT KCKI AND 3SM AT KMKS AS OF 2330Z.
THE FOG WILL INITIALLY BE SHALLOW BUT WILL STEADILY THICKEN
THROUGH THE NIGHT AS SURFACE TEMPERATURES COOL. THERE IS STILL
SOME UNCERTAINTY ON EXACTLY HOW LOW VSBYS WILL GET AS 1000MB
GEOSTROPHIC WINDS ARE FORECAST TO INCREASE AFTER 08Z. THIS MAY
VERY WELL YIELD A BLENDED COMBINATION OF LOW STRATUS AND FOG.
CURRENT TRENDS SUGGEST THERE ARE REASONABLE PROBABILITIES FOR AT
LEAST PREVAILING IFR VSBYS AND THE LATEST SHORT TERM GUIDANCE
SUGGEST VSBYS AT BOTH SITES WILL DROP TO LESS THAN 1/4SM AFTER
08Z. WE ARE NOT QUITE READY TO FORECAST VSBYS THAT LOW GIVEN THE
STRENGTH OF THE GEOSTROPHIC WINDS PROGGED LATER TONIGHT...BUT WILL
CERTAINLY TREND VSBYS DOWN FROM THE 18Z TAFS...SHOWING A TEMPO
GROUP OF 1/2SM FG VV002 AT KCHS AND 3/4SM BR SCT004 AT KSAV.
ADDITIONAL ADJUSTMENTS WILL BE NEEDED AS FOG TRENDS BECOME MORE
APPARENT LATER THIS EVENING AND OVERNIGHT.
THE FOG SHOULD BURN OFF FAIRLY QUICKLY AFTER SUNRISE WITH
CONDITIONS RETURNING TO VFR AFTER 14-15Z.
EXTENDED AVIATION OUTLOOK...MVFR OR LOWER CEILINGS AND
VISIBILITIES POSSIBLE SATURDAY AND SUNDAY. VFR THEREAFTER.
&&
.MARINE...
AS SURFACE HIGH PRESSURE BUILDS EAST AND NORTHEAST TONIGHT THROUGH
FRIDAY...WINDS WILL REMAIN NORTHEASTERLY ACROSS THE WATERS. SPEEDS
WILL REMAIN BELOW 15 KT BUT SEAS WILL REMAIN AS HIGH AS 5 FT. WILL
HAVE TO WATCH TRENDS CAREFULLY FOR THE DEVELOPMENT OF FOG IN THE
CHARLESTON HARBOR LATER TONIGHT. A MARINE DENSE FOG ADVISORY MAY
EVENTUALLY BE NEEDED.
FRIDAY NIGHT THROUGH MONDAY...AN AREA OF LOW PRESSURE WILL
DEVELOP ACROSS THE NORTH-CENTRAL GULF OF MEXICO OVER THE
WEEKEND...WHILE SURFACE HIGH PRESSURE TO THE NORTH MAINTAINS AN
INLAND WEDGE. THIS AREA OF LOW PRESSURE WILL LIFT NORTHEAST AND
LIKELY PROGRESS ALONG THE GEORGIA/SOUTH CAROLINA COASTLINE SUNDAY
AND MONDAY. HIGH PRESSURE WILL THEN BUILD BACK INTO THE AREA NEXT
WEEK.
WINDS AND/OR SEAS COULD APPROACH SMALL CRAFT LEVELS ACROSS
PORTIONS OF THE WATERS SATURDAY NIGHT INTO SUNDAY NIGHT AS THE
AREA OF LOW PRESSURE MAKES ITS CLOSEST APPROACH. DUE TO SOME
UNCERTAINTIES BETWEEN FORECAST MODELS REGARDING THE STRENGTH AND
TRACK OF THE LOW SYSTEM...WILL KEEP WINDS AND SEAS BELOW SMALL
CRAFT THRESHOLDS THROUGH MONDAY AT THIS POINT.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.
&&
$$
000
FXUS62 KCAE 192336
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
636 PM EST THU NOV 19 2009
.SYNOPSIS...
HIGH PRESSURE WILL MOVE INTO THE AREA AND DOMINATE TONIGHT THROUGH
EARLY SATURDAY. A LOW PRESSURE SYSTEM WILL MOVE OUT OF THE GULF OF
MEXICO AND LIKELY BRING RAIN TO THE AREA SATURDAY NIGHT THROUGH
SUNDAY.
&&
.NEAR TERM /TONIGHT/...
THE INVERTED TROUGH HAS SHIFTED EAST OF THE FORECAST AREA. DRIER AIR
HAS MOVED INTO THE REGION BEHIND THIS FEATURE. THE MAIN FORECAST
PROBLEM IS THE FOG POTENTIAL TONIGHT. CONTINUED HIGH LOW-LEVEL
MOISTURE PLUS DIURNAL COOLING WILL LIKELY LEAD TO FOG DEVELOPMENT
LATE. MOST OF THE MOS GUIDANCE PLUS CROSS-OVER TEMPERATURES SUPPORT
FOG. USED THE GUIDANCE CONSENSUS FOR THE TEMPERATURE FORECAST.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY/...
THE NAM AND GFS SHOW DRY RIDGING DOMINATING FRIDAY THROUGH EARLY
SATURDAY. ISENTROPIC LIFT WILL BE ON THE INCREASE SATURDAY AHEAD
OF LOW PRESSURE APPROACHING FROM THE GULF OF MEXICO. THE MAV AND
MET MOS ARE IN GOOD AGREEMENT SHOWING CHANCE POPS IN THE SOUTHWEST
SECTION TO SLIGHT CHANCE POPS IN THE NORTHEAST PART SATURDAY
AFTERNOON. USED THE GUIDANCE CONSENSUS FOR THE TEMPERATURE
FORECAST EXCEPT THE COOLER VALUES APPEARED BETTER SATURDAY BECAUSE
OF EXPECTED CLOUDINESS.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
THE GFS AND ECMWF SHOW HIGH MOISTURE SUNDAY ASSOCIATED WITH LOW
PRESSURE MOVING THROUGH THE AREA. THE MODELS SHOW A DRY PATTERN
DURING THE REST OF THE PERIOD. THE GFS ENSEMBLES INDICATE SEASONABLE
TEMPERATURES.
&&
.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
VFR CONDITIONS WILL CONTINUE THROUGH THE EVENING. CONTINUED HIGH
LOW-LEVEL MOISTURE PLUS DIURNAL COOLING SHOULD RESULT IN IFR FOG
DEVELOPMENT LATE TONIGHT AT AGS AND OGB. LOW END MVFR VISIBILITIES
POSSIBLE LATE TONIGHT AT CAE/CUB/DNL. NAM IS MUCH MORE
PESSIMISTIC...BUT I LEANED MORE TOWARDS THE MAV GUIDANCE THIS RUN.
AFTER SUNRISE FRIDAY...HEATING AND MIXING SHOULD RESULT IN A RETURN
TO VFR CONDITIONS AROUND 14Z AT ALL SITES.
EXTENDED AVIATION OUTLOOK...WIDESPREAD MVFR OR IFR CONDITIONS WILL
LIKELY OCCUR 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.
&&
$$
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