000
ACUS01 KWNS 221922
SWODY1
SPC AC 221920
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0120 PM CST SUN NOV 22 2009
VALID 222000Z - 231200Z
...NO SVR TSTM AREAS FORECAST...
...20Z OUTLOOK UPDATE...
EARLIER LOW SEVERE POTENTIAL ACROSS PARTS OF NORTHERN FLORIDA/
FLORIDA PENINSULA APPEARS TO BE IN THE PROCESS OF DIMINISHING AS A
WEAKENING MID-LEVEL CIRCULATION/TROUGH CONTINUES TO LIFT TOWARD THE
TENNESSEE VALLEY/SOUTHERN APPALACHIANS. A TENDENCY TOWARD
WEAKENING/VEERING OF LOW-LEVEL WIND FIELDS NOW APPEARS UNDERWAY...
AND A SUBSIDENT MID-LEVEL REGIME MAY INHIBIT THE RISK FOR ADDITIONAL
STORMS TO THE NORTH OF ONGOING CONVECTIVE BAND STILL TO THE
NORTH/WEST OF A TAMPA/DAYTONA BEACH LINE. THIS BAND APPEARS FOCUSED
ALONG A LOWER/MID TROPOSPHERIC CONFLUENCE ZONE WHICH MAY ONLY SLOWLY
ADVANCE INTO/THROUGH THE TAMPA/ST. PETERSBURG AND ORLANDO/MELBOURNE
AREAS LATE THIS AFTERNOON AND EVENING...AS AN UPSTREAM SUBTROPICAL
IMPULSE ACCELERATES ACROSS THE EASTERN GULF OF MEXICO.
OTHERWISE...FORCING AHEAD OF THE FRONTAL WAVE NOW BEGINNING TO LIFT
UP THE SOUTH ATLANTIC COAST IS EXPECTED TO PROVIDE THE FOCUS FOR ANY
OTHER CONVECTIVE DEVELOPMENT OF CONCERN. BEYOND THE NEXT HOUR OR
SO...ACTIVITY WILL PROBABLY BE CONFINED TO THE ELEVATED WARM
ADVECTION REGIME ABOVE THE FRONTAL INVERSION OVER INLAND AREAS
NORTHEAST OF COASTAL GEORGIA. DESPITE THE WEAK CAPE...THERMODYNAMIC
PROFILES MAY BE COOL ENOUGH TO SUPPORT THE RISK FOR SMALL HAIL IN
THE MOST VIGOROUS UPDRAFTS.
..KERR.. 11/22/2009
.PREV DISCUSSION... /ISSUED 1010 AM CST SUN NOV 22 2009/
...NRN/CENTRAL FL PENINSULA AND EXTREME SERN GA...
UPPER LOW OVER AL IS FORECAST TO WEAKEN AND LIFT NEWD INTO THE OH
VALLEY TONIGHT...IN RESPONSE TO UPPER TROUGH SHIFTING EWD FROM THE
ROCKIES INTO THE MS VALLY. AT THE SURFACE...WEAK AREA OF LOW
PRESSURE STRETCHED FROM SRN LA EWD INTO THE WRN FL PANHANDLE.
OCCLUDED/WARM FRONT WAS LOCATED WITHIN THIS AREA OF LOW PRESSURE
FROM SERN LA INTO FAR NRN FL...WITH A WEAK COLD FRONT EXTENDING N-S
IN THE NERN GULF...WEST OF THE FL PENINSULA. AT MID MORNING...
STRONG THUNDERSTORMS WERE LOCATED ABOUT 60 NW OF PIE. WHILE MODERATE
INSTABILITY PERSISTED OVER THE NERN GULF WATERS...INSTABILITY WAS
WEAK OVER INLAND AREAS. THIS HAS RESULTED IN STORMS TO BACKBUILD AND
REMAIN OFFSHORE. THIS TREND IS EXPECTED TO CONTINUE FOR THE NEXT FEW
HOURS. THICKER CLOUDS FROM CONVECTION ARE LIKELY TO RESTRICT
WARMING/INSTABILITY ACROSS PORTIONS OF NRN FL. HOWEVER...AS
TEMPERATURES WARM INTO THE 80S NEAR THE SRN EDGE OF THE THICKER
CLOUDS...SUFFICIENT INSTABILITY MAY EXIST FOR STORMS TO MOVE/DEVELOP
INLAND THIS AFTERNOON. WHILE DEEP LAYER SHEAR MAY SUPPORT A SEVERE
STORM OR TWO...LOW LEVEL MASS CONVERGENCE AND UPPER FORCING SHIFTING
NWD AWAY FROM THIS REGION SHOULD KEEP ANY SEVERE THREAT ISOLATED.
000
ACUS02 KWNS 221729
SWODY2
SPC AC 221728
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1128 AM CST SUN NOV 22 2009
VALID 231200Z - 241200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
DOWNSTREAM OF A STRONG ZONAL UPPER JET OVER THE MID LATITUDE
WESTERN/CENTRAL PACIFIC...A GENERALLY WEAKER SPLIT FLOW IS EXPECTED
TO PERSIST ACROSS THE EASTERN PACIFIC THROUGH MUCH OF NORTH AMERICA
AND WESTERN ATLANTIC. SHORT WAVE PERTURBATIONS EMBEDDED WITHIN THIS
REGIME APPEAR LIKELY TO REMAIN PROGRESSIVE THROUGH AT LEAST THIS
FORECAST PERIOD. THIS INCLUDES THE LINGERING REMNANTS OF A CLOSED
LOW/TROUGH NOW LIFTING OUT OF THE SOUTHEASTERN STATES...SHORT WAVE
IMPULSES EMBEDDED WITHIN A STREAM EXTENDING FROM THE SUBTROPICAL
EASTERN PACIFIC THROUGH THE GULF OF MEXICO/FLORIDA PENINSULA...AND A
SIGNIFICANT POLAR TROUGH NOW DIGGING INTO/THROUGH THE NORTHERN GREAT
BASIN. MODELS INDICATE THAT THIS LATTER FEATURE WILL EVOLVE INTO A
CLOSED LOW/MID LEVEL CIRCULATION ACCOMPANIED BY WEAK SURFACE
CYCLOGENESIS AS IT MIGRATES EAST OF THE CENTRAL ROCKIES
MONDAY/MONDAY NIGHT. HOWEVER...IN THE WAKE OF THE WEAKENING LEAD
SYSTEM...BOUNDARY LAYER MODIFICATION OVER THE WESTERN GULF OF MEXICO
MAY NOT SUPPORT A SUBSTANTIAL MOISTURE RETURN MUCH NORTH OF DEEP
SOUTH TEXAS/TEXAS COASTAL AREAS BY 12Z TUESDAY.
...SOUTHEAST...
ALTHOUGH A WEAK SURFACE LOW IS PROGGED TO MIGRATE NORTHEASTWARD
ALONG OR JUST EAST OF SOUTH ATLANTIC COASTAL AREAS...A TRAILING
SURFACE FRONT ACROSS THE NORTHERN FLORIDA PENINSULA INTO THE
NORTHEASTERN GULF OF MEXICO IS LIKELY TO REMAIN SLOW MOVING OR
QUASI-STATIONARY. IN THE PRE-FRONTAL ENVIRONMENT ACROSS MUCH OF THE
CENTRAL AND SOUTHERN PENINSULA...MODELS SUGGEST THAT HEATING OF A
MODESTLY MOIST BOUNDARY LAYER WILL BECOME SUPPORTIVE OF WEAK TO
MODERATE CAPE BY MONDAY AFTERNOON. COUPLED WITH A LINGERING
WEAKNESS IN MID-LEVEL INHIBITION...THIS MAY BECOME SUFFICIENT FOR AT
LEAST SCATTERED THUNDERSTORM ACTIVITY...WHICH COULD PERSIST INTO
EARLY EVENING...DESPITE WEAK MID/UPPER FORCING FOR UPWARD VERTICAL
MOTION.
...CENTRAL STATES...
THE RISK FOR THUNDERSTORM ACTIVITY MAY INCREASE LATE MONDAY/MONDAY
NIGHT IN ASSOCIATION WITH STRENGTHENING MID/UPPER FORCING FOR UPWARD
VERTICAL MOTION ACROSS PARTS OF THE EAST CENTRAL PLAINS INTO THE
LOWER MISSOURI VALLEY. UPPER FORCING ASSOCIATED WITH SUBTROPICAL
IMPULSES COULD ALSO CONTRIBUTE TO CONVECTIVE POTENTIAL NEAR SOUTHERN
TEXAS COASTAL AREAS. HOWEVER ...WITH STRONGEST DESTABILIZATION
EXPECTED TO REMAIN MODEST...AT BEST...AND DISPLACED FROM STRONGER
SHEAR AND LARGE SCALE ASCENT...THE POTENTIAL FOR SEVERE STORMS STILL
SEEMS NEGLIGIBLE.
..KERR.. 11/22/2009
000
ACUS01 KWNS 221611
SWODY1
SPC AC 221610
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1010 AM CST SUN NOV 22 2009
VALID 221630Z - 231200Z
...NO SVR TSTM AREAS FORECAST...
...NRN/CENTRAL FL PENINSULA AND EXTREME SERN GA...
UPPER LOW OVER AL IS FORECAST TO WEAKEN AND LIFT NEWD INTO THE OH
VALLEY TONIGHT...IN RESPONSE TO UPPER TROUGH SHIFTING EWD FROM THE
ROCKIES INTO THE MS VALLY. AT THE SURFACE...WEAK AREA OF LOW
PRESSURE STRETCHED FROM SRN LA EWD INTO THE WRN FL PANHANDLE.
OCCLUDED/WARM FRONT WAS LOCATED WITHIN THIS AREA OF LOW PRESSURE
FROM SERN LA INTO FAR NRN FL...WITH A WEAK COLD FRONT EXTENDING N-S
IN THE NERN GULF...WEST OF THE FL PENINSULA. AT MID MORNING...
STRONG THUNDERSTORMS WERE LOCATED ABOUT 60 NW OF PIE. WHILE MODERATE
INSTABILITY PERSISTED OVER THE NERN GULF WATERS...INSTABILITY WAS
WEAK OVER INLAND AREAS. THIS HAS RESULTED IN STORMS TO BACKBUILD AND
REMAIN OFFSHORE. THIS TREND IS EXPECTED TO CONTINUE FOR THE NEXT FEW
HOURS. THICKER CLOUDS FROM CONVECTION ARE LIKELY TO RESTRICT
WARMING/INSTABILITY ACROSS PORTIONS OF NRN FL. HOWEVER...AS
TEMPERATURES WARM INTO THE 80S NEAR THE SRN EDGE OF THE THICKER
CLOUDS...SUFFICIENT INSTABILITY MAY EXIST FOR STORMS TO MOVE/DEVELOP
INLAND THIS AFTERNOON. WHILE DEEP LAYER SHEAR MAY SUPPORT A SEVERE
STORM OR TWO...LOW LEVEL MASS CONVERGENCE AND UPPER FORCING SHIFTING
NWD AWAY FROM THIS REGION SHOULD KEEP ANY SEVERE THREAT ISOLATED.
..IMY/SMITH.. 11/22/2009
000
ACUS01 KWNS 221235
SWODY1
SPC AC 221233
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0633 AM CST SUN NOV 22 2009
VALID 221300Z - 231200Z
...NO SVR TSTM AREAS FORECAST...
...SERN STATES...
UPPER LOW/TROUGH GULF STATES WILL CONTINUE TO SLOWLY WEAKEN AND LIFT
ENEWD INTO THE CAROLINAS BY TONIGHT. EVEN SO...GIVEN SUFFICIENT
INSTABILITY THERE IS ADEQUATE UPPER SUPPORT/SHEAR FOR A LOW END
THREAT OF SEVERE STORMS. THE PRIMARY QUESTION IS THE AMOUNT OF
DESTABILIZATION THAT CAN OCCUR AS A DIFFUSE E/W WARM FRONT DEVELOPS
NWD ACROSS NRN FL TO ENEWD OFF THE SERN COAST. ATTM GIVEN THE
CLOUDINESS SPREADING ACROSS MUCH OF FL PENINSULA IT WILL BE
DIFFICULT FOR THE WARM SECTOR TO HEAT SUFFICIENTLY TO DEVELOP MUCH
MORE MLCAPE THAN ABOUT 500 J/KG.
NEVERTHELESS WILL MAINTAIN A LOW PROB OF SEVERE VICINITY THE FRONTAL
ZONE WHERE SOME ENHANCED SHEAR WILL FAVOR ROTATING UPDRAFTS AND A
SMALL CHANCE OF A BRIEF TORNADO AND/OR GUSTY WINDS. ANY THREAT
SHOULD END BY 00Z WHEN SHEAR WEAKENS AND ANY HEATING CEASES.
..HALES/JEWELL.. 11/22/2009
000
ACUS03 KWNS 220721
SWODY3
SPC AC 220720
DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0120 AM CST SUN NOV 22 2009
VALID 241200Z - 251200Z
...SYNOPSIS/FCST...
UPR LOW OVER THE LWR MO VLY EARLY TUESDAY WILL EJECT ENE ACROSS THE
MIDWEST DURING THE DAY AS THE NEXT NRN STREAM SYSTEM DIGS INTO THE
NRN PLNS. SFC LOW ATTENDANT WITH THE FORMER SYSTEM WILL MOVE FROM
THE CORN BELT INTO LWR MI BY 12Z WED AS THE CDFNT MOVES THROUGH THE
MIDWEST...THE OH/TN VLYS AND WRN GULF OF MEXICO. TO THE S...AN OLD
FRONT WILL REMAIN SITUATED FROM SRN FL WWD INTO THE CNTRL GULF OF
MEXICO WHERE A FRONTAL WAVE IS APT TO FORM IN RESPONSE TO SRN STREAM
ENERGY EJECTING NEWD FROM CNTRL MEXICO
SPORADIC TSTMS MAY ACCOMPANY THE STRONG PV-ANOMALY AS IT TRACKS INTO
THE MIDWEST TUESDAY MORNING/AFTN. MOISTURE WILL REMAIN QUITE
LIMITED...ESPECIALLY AS THE OVERALL FLOW TURNS NLY ACROSS THE NRN
GULF BASIN IN RESPONSE TO THE FRONTAL WAVE OVER THE WRN GULF WATERS.
THUS...SVR WEATHER IS NOT ANTICIPATED DESPITE FAVORABLE KINEMATICS.
OTHERWISE...CONVECTION/ISOLD TSTMS MAY ACCOMPANY THE FRONTAL PASSAGE
ACROSS DEEP S TX DURING THE FIRST HALF OF TUESDAY. PRIMARY FORCING
FOR ASCENT AND DEEP LAYER FLOW PASSING TO THE N OF THE REGION AND
PRESENCE OF A RESIDUAL WARM LAYER NEAR H85 SHOULD REDUCE THE THREAT
FOR SVR TSTMS.
..RACY.. 11/22/2009
000
ACUS02 KWNS 220541
SWODY2
SPC AC 220540
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1140 PM CST SAT NOV 21 2009
VALID 231200Z - 241200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
NRN BRANCH UPR TROUGH MOVING INTO THE PAC NW EARLY SUNDAY WILL
QUICKLY TRANSLATE SEWD AND CLOSE INTO A LOW OVER THE CNTRL PLNS BY
MONDAY NIGHT. SYSTEM WILL INDUCE SFC CYCLOGENESIS OVER ERN CO EARLY
IN THE PD...WITH THE LOW DEVELOPING ENE INTO SERN NEB BY 12Z
TUESDAY. A STG CDFNT WILL TRAIL THE LOW AND SURGE SEWD ACROSS THE
PLNS...REACHING ERN KS...SERN OK AND CNTRL TX BY DAYBREAK TUESDAY.
...CNTRL/SRN PLNS...
RAPID SUCCESSION OF NRN STREAM WAVES WILL PRECLUDE QUALITY MOISTURE
RETURN AHEAD OF THE AFOREMENTIONED DIGGING UPR TROUGH. WARM SECTOR
WILL MOISTEN SOME...HOWEVER...WITH PWATS RANGING FROM AROUND 0.75
INCH JUST AHEAD OF THE CDFNT IN THE CNTRL PLNS TO NEAR 1.25 INCHES
ALONG THE TX GULF CST. BANDS OF CONVECTION WILL LIKELY EVOLVE
ALONG/BEHIND THE SURGING CDFNT LATE MONDAY AS 60-METER/12-HR HEIGHT
FALLS AND COLD TEMPERATURES ALOFT SPREAD ACROSS THE CNTRL PLNS.
FCST THERMODYNAMIC PROFILES SUGGEST THAT BUOYANCY WILL BE
MARGINAL...BUT GIVEN SUCH STG FORCING FOR ASCENT...SPORADIC TSTMS
WILL BE POSSIBLE. ACTIVITY WILL PROBABLY BEGIN OVER CNTRL OK...ERN
KS...EXTREME SERN NEB AND THEN EXPAND DOWNSTREAM INTO PARTS OF SRN
IA...NRN/WRN MO...WRN AR AND PARTS OF NERN TX LATER MONDAY NIGHT.
DESPITE STRONG DEEP LAYER SHEAR...MEAGER THERMAL BUOYANCY WILL
PRECLUDE SVR TSTMS.
MEANWHILE...FARTHER S...DEEPENING MOIST PROFILES WILL RESULT IN
CONSIDERABLE CLOUDS AND SHALLOW CONVECTION THROUGH THE DAY MONDAY
ACROSS CNTRL/SRN TX. CINH IS LIABLE TO REMAIN FAIRLY STRONG THROUGH
MONDAY NIGHT WITH HIGHER PROBABILITIES FOR TSTMS LIKELY HOLDING OFF
UNTIL BEYOND THE DAY 2 PD ACROSS CNTRL/SRN TX.
..RACY.. 11/22/2009
000
ACUS01 KWNS 220517
SWODY1
SPC AC 220515
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1115 PM CST SAT NOV 21 2009
VALID 221200Z - 231200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
DEEP-LAYER CYCLONE CURRENTLY OVER THE LOWER MS VALLEY IS FORECAST TO
WEAKEN THROUGH THE DAY ONE PERIOD AS IT EVOLVES INTO AN OPEN WAVE
WHILE TRANSLATING NEWD TOWARD THE MID ATLANTIC COAST. ATTENDANT
SURFACE CYCLONE WILL CONCURRENTLY WEAKEN OVER THE FAR NERN GULF OF
MEXICO BEFORE REFORMING TONIGHT OFF THE SERN ATLANTIC COAST.
PERSISTENT SURFACE RIDGING E OF THE APPALACHIANS SHOULD SUPPORT
INTENSIFICATION OF W-E ORIENTED BAROCLINIC ZONE TODAY ACROSS NRN FL
WITH ANY THREAT OF SEVERE WEATHER REMAINING CONFINED TO ALONG AND S
OF THIS BOUNDARY.
...NRN FL/SRN GA...
GRADUALLY WEAKENING SWLY LLJ WILL BE MAINTAINED AHEAD OF EJECTING
SHORT WAVE TROUGH...SUPPORTING AN INCREASE IN DEWPOINTS THROUGH THE
60S S OF FRONTAL ZONE. DESPITE THE INCREASING BOUNDARY LAYER
MOISTURE...POOR LAPSE RATES /MOST NOTABLY IN THE 700-500 MB LAYER/
WILL EFFECTIVELY LIMIT THE DEGREE OF AIR MASS DESTABILIZATION WITH
MLCAPE REMAINING GENERALLY BELOW 1000 J/KG.
TSTMS CURRENTLY IN PROGRESS OVER THE NERN GULF OF MEXICO ARE
EXPECTED TO SPREAD NEWD ACROSS THE REGION TODAY WITHIN SRN FRINGE OF
STRONGER DYNAMIC FORCING FOR ASCENT ASSOCIATED WITH DE-AMPLIFYING
MIDLEVEL WAVE. A BELT OF 45-50 KT SWLY MIDLEVEL FLOW WILL ACCOMPANY
VORTICITY MAXIMUM NEWD...EFFECTIVELY CONTRIBUTING TO AROUND 40 KT OF
DEEP-LAYER SHEAR ACROSS NRN EXTENSION OF SYSTEM WARM SECTOR. THIS
INCREASE IN VERTICAL SHEAR MAY BE SUFFICIENT TO SUPPORT EPISODIC
SUPERCELL AND/OR BOWING STRUCTURES EMBEDDED WITHIN LARGER-SCALE
CONVECTIVE SYSTEM. WHILE AN ISOLATED STRONG WIND GUST OR BRIEF
TORNADO ARE POSSIBLE...THE WEAK LAPSE RATES...MARGINAL CONVECTIVE
INSTABILITY AND OVERALL WEAKENING OF SYNOPTIC SYSTEM WITH TIME ARE
EXPECTED TO PRECLUDE A MORE ROBUST SEVERE WEATHER THREAT.
..MEAD/GRAMS.. 11/22/2009
000
ACUS01 KWNS 220048
SWODY1
SPC AC 220046
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0646 PM CST SAT NOV 21 2009
VALID 220100Z - 221200Z
...NO SVR TSTM AREAS FORECAST...
...CNTRL/ERN GULF COAST...
SURFACE LOW CURRENTLY JUST S OF THE LA COAST IS FORECAST TO MOVE
INLAND TO OVER SERN MS BY 22/12Z. ATTENDANT WARM FRONT /NOW 50-100
NM S OF THE MS/AL/FL PNHDL COASTS/ WILL APPROACH THE COAST LATE IN
THE PERIOD WITH TSTMS CONCURRENTLY MOVING/DEVELOPING NWD/NEWD WITHIN
STRENGTHENING LOW-LEVEL WAA REGIME. THE MAJORITY OF TSTMS WILL
LIKELY REMAIN SLIGHTLY ELEVATED ABOVE A SHALLOW NEAR-SURFACE
INVERSION WITH ANY MORE SUBSTANTIAL SURFACE-BASED SEVERE THREAT
REMAINING OFFSHORE THROUGH THE REMAINDER OF THE PERIOD.
..MEAD.. 11/22/2009
000
ACUS01 KWNS 211946
SWODY1
SPC AC 211945
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0145 PM CST SAT NOV 21 2009
VALID 212000Z - 221200Z
...NO SVR TSTM AREAS FORECAST...
...SERN LA...
EARLY AFTERNOON SURFACE OBSERVATIONS/VISIBLE SATELLITE IMAGERY
INDICATED SOME BREAKS IN THE CLOUD COVER OVER SERN LA...BOOSTING
SURFACE TEMPERATURES. HOWEVER...ENELY SURFACE TRAJECTORIES ARE
MAINTAINING MODEST LOW LEVEL MOISTURE /SURFACE DEWPOINTS LOWER-MID
50S/ OVER INLAND LOCATIONS. SURFACE ANALYSIS SHOWED AN OCCLUDED LOW
PRESSURE AREA HAS REMAINED OFFSHORE...THUS FAR...BUT IS EXPECTED TO
MOVE ACROSS SERN LA THIS FORECAST PERIOD. REGIONAL RADARS INDICATED
A COUPLE OF STRONGER STORMS HAD FORMED SINCE THIS MORNING IN THE
VICINITY OF THE OCCLUDED LOW...BUT WEAKENED ONCE THEY TRACKED NWD
INTO A MORE STABLE BOUNDARY LAYER.
ADDITIONAL STORMS WERE LOCATED OVER THE CENTRAL GULF WITHIN THE WARM
SECTOR. ALTHOUGH THE OCCLUDED LOW SHOULD MOVE OVER SERN LA...
EXTENSIVE CLOUDS/PRECIPITATION LOCATED OVER THE NORTH CENTRAL GULF
/ALONG AND E OF THE MS DELTA REGION/ SHOULD MAINTAIN A MORE STABLE
AIR MASS OVER THIS AREA...AND THUS PRECLUDE THE TRIPLE POINT AND
WARM SECTOR FROM MOVING VERY FAR NWD. THERE ARE NO CHANGES TO THE
SEVERE WEATHER PROBABILITIES WITH THIS OUTLOOK ISSUANCE...BUT THE
GENERAL TSTM LINE HAS BEEN SHIFTED N/NWWD ACROSS SRN/SERN LA TO
ACCOUNT FOR TRENDS OF ELEVATED STORMS TRACKING INLAND IN ADVANCE OF
THE OCCLUSION.
..PETERS.. 11/21/2009
.PREV DISCUSSION... /ISSUED 1003 AM CST SAT NOV 21 2009/
......SERN LA...
AS UPPER TROUGH SHIFTS EWD FROM THE INTERMOUNTAIN WEST INTO THE
NRN/CENTRAL ROCKIES...UPPER LOW...OVER SRN TX THIS MORNING...IS
FORECAST TO EJECT EWD THROUGH THE LOWER MS VALLEY REGION THROUGH THE
PERIOD. SATELLITE AND SURFACE OBSERVATIONS SHOWED A SURFACE LOW WAS
LOCATED ABOUT 100 MI SOUTH OF LCH...WITH A WARM FRONT STRETCHING
FROM THE LOW ESEWD TO FL KEYS. THIS SURFACE LOW IS EXPECTED TO SHIFT
MOSTLY EWD AND MAY EVEN CROSS THE FAR SERN PORTIONS OF LA LATE THIS
AFTERNOON/EVENING. HOWEVER...SATELLITE IMAGERY SUGGESTS THE SURFACE
LOW HAS ALREADY BECOME OCCLUDED AS A TRAILING COLD FRONT AND
ASSOCIATED CONVECTION APPEAR TO BE SURGING EWD FASTER THAN THE LOW
PRESSURE SYSTEM. THIS TREND SHOULD CONTINUE AS STRONGER WINDS
ALOFT...OVER THE CENTRAL/NRN GULF WATERS...PUSH DRIER AND COOLER AIR
EWD AND PINCH OFF THE RICHER GULF MOISTURE...SOUTH OF THE WARM FRONT
AND EAST OF THE COLD FRONT IN THE GULF. THEREFORE...EVEN AS THE LOW
MOVES INLAND LATER TODAY...ANY THREAT FOR SEVERE STORMS SHOULD
REMAIN CONFINED SOUTH AND EAST OF LA OVER THE NRN GULF WATERS.
000
ACUS02 KWNS 211717
SWODY2
SPC AC 211716
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1116 AM CST SAT NOV 21 2009
VALID 221200Z - 231200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
MODELS ARE IN AGREEMENT THROUGH THE DAY 2 PERIOD SHOWING A SHORT
WAVE TROUGH...CURRENTLY MOVING EWD THROUGH SRN TX/NWRN GULF OF
MEXICO PER WATER VAPOR IMAGERY...WILL DEAMPLIFY SUNDAY AS THIS
FEATURE TRACKS THROUGH THE TN/OH VALLEYS. AN OCCLUDED SURFACE LOW
AND TRIPLE POINT LOCATED ALONG THE MS DELTA AND CENTRAL GULF
COAST... RESPECTIVELY...AT 12Z SUNDAY WILL WEAKEN THIS PERIOD. AS
THIS PROCESS OCCURS...A NEW SURFACE LOW IS EXPECTED TO DEVELOP OFF
THE SRN ATLANTIC COAST /E OF GA/. MEANWHILE...GRADUAL HEIGHT RISES
OVER THE SERN STATES WITH THE NEWD TRACK OF THE UPPER TROUGH SUGGEST
A SURFACE FRONT RESIDING FROM NWRN FL TO SERN GA SHOULD REMAIN
QUASI-STATIONARY THROUGH 12Z MONDAY.
...NRN FL PENINSULA/SERN GA...
CURRENT THINKING REMAINS SIMILAR TO THE INITIAL DAY 2 OUTLOOK FOR AN
ISOLATED THREAT FOR SEVERE STORMS...WITH THE PRIMARY THREAT BEING
FOR A NON-ZERO POTENTIAL FOR AN ISOLATED/BRIEF TORNADO. DEEP LAYER
AND LOW LEVEL SHEAR VALUES WILL BE FAVORABLE FOR ORGANIZED STORMS/
ROTATING UPDRAFTS THROUGH EARLY-MID SUNDAY AFTERNOON BEFORE THESE
FAVORABLE KINEMATICS SHIFT NWD AWAY FROM THE WARM SECTOR.
HOWEVER...BOUNDARY LAYER DESTABILIZATION REMAINS THE PRIMARY
LIMITING FACTOR GIVEN WEAK LAPSE RATES AND CLOUDINESS/PRECIPITATION
ACROSS THE AREA OF CONCERN PRECLUDING GREATER INSTABILITY
DEVELOPING. WIDESPREAD SEVERE STORMS ARE NOT EXPECTED...BUT ANY
AREAS THAT HAVE SOME SURFACE HEATING/DESTABILIZATION MAY PROVE
SUFFICIENT FOR DEEP MOIST CONVECTION WITH A LOW SEVERE PROBABILITY
GIVEN THE FAVORABLE KINEMATICS. THE 5 PERCENT SEVERE PROBABILITY
HAS BEEN SHIFTED A LITTLE WWD OVER THE FL PANHANDLE. THIS IS
PRIMARILY ALONG THE COASTAL AREAS TO ACCOUNT FOR THE TRIPLE POINT
LOW REACHING THIS REGION SUNDAY AFTERNOON...AND SUBSEQUENTLY
ENHANCING LOW LEVEL SHEAR VALUES FOR AN ISOLATED/BRIEF TORNADO
AND/OR WATERSPOUT MOVING ONSHORE.
..PETERS.. 11/21/2009
000
ACUS01 KWNS 211604
SWODY1
SPC AC 211603
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1003 AM CST SAT NOV 21 2009
VALID 211630Z - 221200Z
...NO SVR TSTM AREAS FORECAST...
......SERN LA...
AS UPPER TROUGH SHIFTS EWD FROM THE INTERMOUNTAIN WEST INTO THE
NRN/CENTRAL ROCKIES...UPPER LOW...OVER SRN TX THIS MORNING...IS
FORECAST TO EJECT EWD THROUGH THE LOWER MS VALLEY REGION THROUGH THE
PERIOD. SATELLITE AND SURFACE OBSERVATIONS SHOWED A SURFACE LOW WAS
LOCATED ABOUT 100 MI SOUTH OF LCH...WITH A WARM FRONT STRETCHING
FROM THE LOW ESEWD TO FL KEYS. THIS SURFACE LOW IS EXPECTED TO SHIFT
MOSTLY EWD AND MAY EVEN CROSS THE FAR SERN PORTIONS OF LA LATE THIS
AFTERNOON/EVENING. HOWEVER...SATELLITE IMAGERY SUGGESTS THE SURFACE
LOW HAS ALREADY BECOME OCCLUDED AS A TRAILING COLD FRONT AND
ASSOCIATED CONVECTION APPEAR TO BE SURGING EWD FASTER THAN THE LOW
PRESSURE SYSTEM. THIS TREND SHOULD CONTINUE AS STRONGER WINDS
ALOFT...OVER THE CENTRAL/NRN GULF WATERS...PUSH DRIER AND COOLER AIR
EWD AND PINCH OFF THE RICHER GULF MOISTURE...SOUTH OF THE WARM FRONT
AND EAST OF THE COLD FRONT IN THE GULF. THEREFORE...EVEN AS THE LOW
MOVES INLAND LATER TODAY...ANY THREAT FOR SEVERE STORMS SHOULD
REMAIN CONFINED SOUTH AND EAST OF LA OVER THE NRN GULF WATERS.
..IMY/SMITH.. 11/21/2009
000
ACUS01 KWNS 211221
SWODY1
SPC AC 211220
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0620 AM CST SAT NOV 21 2009
VALID 211300Z - 221200Z
...NO SVR TSTM AREAS FORECAST...
IT NOW APPEARS THAT THE SURFACE LOW CURRENTLY WELL OFFSHORE SWRN LA
WILL CONTINUE E TO ENE TO A POSITION STILL S OF MS DELTA TONIGHT.
THIS IS EXPECTED TO PRECLUDE THE WARM SECTOR FROM REACHING THE COAST
THRU TONIGHT. WHILE LARGE SCALE ASCENT PROVIDED BY THE WARM
ADVECTION AND APPROACHING UPPER TROUGH OVER TX WILL SPREAD ELEVATED
CONVECTION ONTO THE CENTRAL GULF COASTAL AREAS...LACK OF OTHER THAN
SOME ELEVATED INSTABILITY WILL PRECLUDE ANY SEVERE THREAT OVER LAND.
..HALES/JEWELL.. 11/21/2009
000
ACUS03 KWNS 210715
SWODY3
SPC AC 210713
DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0113 AM CST SAT NOV 21 2009
VALID 231200Z - 241200Z
...SYNOPSIS/FCST...
VIGOROUS UPR TROUGH THAT WILL BE MOVING INTO THE CNTRL/NRN ROCKIES
LATE IN THE WEEKEND WILL CLOSE OFF INTO A LOW OVER THE CNTRL/SRN
PLNS ON MONDAY. SYSTEM WILL INDUCE CYCLOGENESIS OVER THE HIGH PLNS
WITH THE LOW DEVELOPING INTO THE MID-MO VLY BY 12Z TUE. TRAILING
THE LOW...A CDFNT WILL SWEEP SEWD ACROSS THE PLNS...REACHING ERN
NEB/KS AND CNTRL OK/TX BY EARLY TUESDAY.
WAVELENGTH BETWEEN THE WEEKEND SYSTEM AND AFOREMENTIONED IMPULSE
WILL BE SHORT AND RETURN FLOW WILL ADVECT ONLY A PARTIALLY MODIFIED
GULF AIR MASS NWD INTO THE PLNS AHEAD OF THE CDFNT. TSTM POTENTIAL
WILL PROBABLY BE MAXIMIZED ALONG/N OF THE RED RVR VLY WHERE
STRONGEST LARGE SCALE LIFT WILL OCCUR MONDAY NIGHT...NAMELY FROM
PARTS OF THE LWR MO VLY SWD INTO ERN OK. INSTABILITY WILL BE WEAK
AND NO SVR TSTMS ARE EXPECTED ATTM.
OTHERWISE...FARTHER S...THERMODYNAMIC PROFILES CHARACTERIZED BY AN
H85-H7 WARM NOSE /OWING TO MEAN WLY FLOW ALONG BASE OF THE TROUGH/
AND LACK OF OVERALL FORCING FOR ASCENT SHOULD PROVE DETRIMENTAL IN
SUPPORTING DEEP MOIST CONVECTION.
..RACY.. 11/21/2009
000
ACUS02 KWNS 210544
SWODY2
SPC AC 210543
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1143 PM CST FRI NOV 20 2009
VALID 221200Z - 231200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
UPR TROUGH OVER E TX IS EXPECTED TO WEAKEN AND BECOME ABSORBED INTO
THE NRN STREAM OVER THE TN/OH VLYS BY SUNDAY NIGHT.
UPSTREAM...STRONG IMPULSE DIGGING SEWD TO THE S OF THE ALEUTIANS
WILL ARRIVE ONSHORE THE PAC NW EARLY SUNDAY...THEN INTO THE
NRN/CNTRL ROCKIES BY 12Z MONDAY.
...SERN GA/NRN FL...
SFC LOW ATTENDANT WITH THE DEAMPLIFYING UPR TROUGH WILL WEAKEN WITH
TRAILING PRE-FRONTAL TROUGH/CDFNT SETTLING SEWD TOWARD NWRN FL LATE
SUNDAY AFTN. MORNING TSTM CLUSTERS/LINES MOVING INTO CNTRL/SRN GA
WILL LIKELY REINFORCE THE E-W ORIENTED BAROCLINIC ZONE ALONG THE
GA/FL BORDER.
SOME RECOVERY OF LLVL MOISTURE WILL OCCUR OVER NRN FL IN WAKE OF
MORNING PCPN...BUT FCST SOUNDINGS EXHIBIT POOR LAPSE RATES AND
BUOYANCY WILL LIKELY BE LIMITED. NONETHELESS...UNTIL THE LOW AND
MID-LVL WIND FIELDS BEGIN TO RELAX DURING THE LATTER HALF OF THE
PD...THERE WILL BE A NON-ZERO THREAT FOR AN ISOLD STG/SVR TSTM
ACROSS NRN FL/SERN GA. SUFFICIENT 0-1KM SHEAR WILL BE PRESENT TO
SUPPORT AN ISOLD AND BRIEF TORNADO. WIDESPREAD SVR TSTMS ARE NOT
EXPECTED.
..RACY.. 11/21/2009
000
ACUS01 KWNS 210542
SWODY1
SPC AC 210540
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1140 PM CST FRI NOV 20 2009
VALID 211200Z - 221200Z
...NO SVR TSTM AREAS FORECAST...
...CENTRAL AND EASTERN GULF COAST...
LATE EVENING SATELLITE IMAGERY CLEARLY DEPICTS CENTER OF UPPER VORT
OVER THE MIDDLE TX COAST...EJECTING ENEWD IN LINE WITH LATEST SHORT
RANGE MODEL GUIDANCE. THIS FEATURE SHOULD TRANSLATE ACROSS THE
CNTRL GULF COAST TOWARD THE FL PANHANDLE/GA WHERE MODEL GUIDANCE
BEGINS TO DIVERGE IN THEIR SOLUTIONS REGARDING THE PLACEMENT OF
UPPER SPEED MAX/TROUGH AXIS. IT APPEARS THE LOW LATITUDE H5 SPEED
MAX WILL ENCOURAGE THE PRIMARY BAROCLINIC ZONE TO REMAIN JUST
OFFSHORE...THOUGH WEAK SFC CYCLOGENESIS MAY BRIEFLY MOVE INLAND
ALLOWING MODIFIED GULF AIRMASS TO RETURN TO COASTAL AREAS. IF UPPER
60S-70F DEW POINTS DO SPREAD INLAND...NEAR-SFC BASED ROBUST
THUNDERSTORM ACTIVITY COULD DEVELOP. IN ALL LIKELIHOOD CONTINENTAL
AIRMASS WILL STUBBORNLY RETREAT AND ONSHORE BOUNDARY LAYER WILL
STRUGGLE TO DESTABILIZE. AS A RESULT...WILL MAINTAIN LOW
PROBABILITIES FOR SEVERE THUNDERSTORMS PREDICATED ON THIS SCENARIO.
..DARROW/GRAMS.. 11/21/2009
000
ACUS01 KWNS 210052
SWODY1
SPC AC 210050
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0650 PM CST FRI NOV 20 2009
VALID 210100Z - 211200Z
...NO SVR TSTM AREAS FORECAST...
...WRN GULF OF MEXICO/SOUTH TX...
WLY FLOW IS DEEPENING ACROSS SOUTH TX THIS EVENING AS COLD FRONT
PROGRESSES INTO THE WRN GULF OF MEXICO. RADAR DATA CONFIRMS THIS
WITH STRONGEST CONVECTION NOW OFFSHORE AND MIGRATING INTO HIGHER
INSTABILITY. GIVEN THIS EVOLUTION IT APPEARS SEVERE THREAT IS
NEGLIGIBLE THE REST OF THE PERIOD.
...PACIFIC NW COAST...
00Z SOUNDINGS FROM UIL/SLE/MFR EXHIBIT VERY STEEP LAPSE RATES IN THE
LOWEST 4KM WITH SUFFICIENT MOISTURE/BUOYANCY FOR LOW-TOPPED
CONVECTION. ISOLATED THUNDERSTORMS ARE CURRENTLY ONGOING ACROSS SRN
VANCOUVER ISLAND AND THIS ACTIVITY MAY PROPAGATE INTO PORTIONS OF
NWRN WA SHORTLY. OTHERWISE...ISOLATED LIGHTNING MAY ACCOMPANY
DEEPER UPDRAFTS SWD ALONG ORE COAST THIS EVENING.
..DARROW.. 11/21/2009
000
ACUS01 KWNS 201933
SWODY1
SPC AC 201931
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0131 PM CST FRI NOV 20 2009
VALID 202000Z - 211200Z
...NO SVR TSTM AREAS FORECAST...
...SOUTH TX/LOWER TX COAST...
MADE TWO CHANGES FOR THE 20Z OUTLOOK. THE FIRST IS TO REMOVE THE 5
PERCENT HAIL PROBABILITY. WEAK LAPSE RATES AND INSTABILITY SHOULD
LIMIT THE HAIL POTENTIAL ACROSS SOUTH TX. THE SECOND IS TO TRIM THE
WRN EDGE OF THE 5 PERCENT WIND AND 2 PERCENT TORNADO PROBABILITIES
TO ALIGN WITH THE COLD FRONT AND ONGOING CONVECTION. REGIONAL
WSR-88D VWPS AND OBJECTIVE ANALYSIS ALONG THE LOWER TX COAST
CONTINUE TO SHOW 0-6 KM SHEAR VALUES RANGING FROM 50 KT IN THE
BROWNSVILLE AREA TO AROUND 70 KT IN THE CORPUS CHRISTI AREA. IN
SPITE OF WEAK INSTABILITY...THE STRONG VERTICAL SHEAR MAY SUPPORT A
MARGINAL SEVERE THREAT WITH THE MORE INTENSE CELLS THIS AFTERNOON
BEFORE THE FRONT MOVES OFFSHORE.
..BROYLES.. 11/20/2009
.PREV DISCUSSION... /ISSUED 1017 AM CST FRI NOV 20 2009/
...SYNOPSIS...
WEAK LONGWAVE RIDGING WAS LOCATED OVER THE ROCKIES...WITH A BROAD
TROUGH MOVING EWD ACROSS THE CENTRAL PORTIONS OF THE COUNTRY. THE
ONLY CONVECTIVE AREA OF INTEREST FOR POSSIBLE SEVERE STORMS TODAY
WILL BE ASSOCIATED WITH AN EMBEDDED SHORTWAVE TROUGH LOCATED ON THE
SRN END OF THE LARGER SCALE TROUGH...OVER THE BIG BEND AREA OF
TEXAS.
...SRN TX...
AT MID MORNING...ELEVATED THUNDERSTORMS STRETCHED FROM NEAR SAT TO
LRD...AND APPEARED TO BE OCCURRING WITHIN REGION OF STRONGER FORCING
ALOFT. THESE STORMS ARE LIKELY TO INTENSIFY AS THEY SPREAD EWD
THROUGH THE DAY INTO A SLOWLY WARMING AND DESTABILIZING AIR MASS. AS
TEMPERATURES WARM INTO THE MID/UPPER 70S...STORMS MAY BECOME SURFACE
BASED BY MID AFTERNOON...ESPECIALLY ALONG AND EAST OF A NIR-MFE
LINE. MUCAPES BETWEEN 1000-2000 J/KG AND 30-40 KT DEEP LAYER SHEAR
MAY BE SUFFICIENT FOR AN ISOLATED SEVERE STORM OR TWO...WITH
MARGINAL SEVERE HAIL/WIND GUSTS. HOWEVER...SEVERE PROBABILITIES
REMAIN LOW DUE TO EXTENSIVE CLOUDS...WEAK WINDS IN THE LOWER 2-3 KM
AND STRONGER CONVECTION/INSTABILITY SITUATED EAST OF THE MAINLAND IN
THE WRN GULF.
000
ACUS02 KWNS 201719
SWODY2
SPC AC 201718
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1118 AM CST FRI NOV 20 2009
VALID 211200Z - 221200Z
...NO SVR TSTM AREAS FORECAST...
...GULF COAST STATES...
A UPPER-LEVEL TROUGH WILL TEMPORARILY CLOSE-OFF OVER THE SRN PLAINS
TONIGHT BEFORE OPENING AND BECOMING DEAMPLIFIED ENEWD INTO THE LOWER
MS VALLEY SATURDAY NIGHT. AHEAD OF THE TROUGH AXIS...STRONG
LARGE-SCALE ASCENT AND WARM ADVECTION SHOULD SUPPORT THE DEVELOPMENT
OF SCATTERED TO NUMEROUS THUNDERSTORMS SATURDAY AFTERNOON ACROSS LA
AND SRN MS. ALTHOUGH VERTICAL SHEAR WILL BE QUITE STRONG IN THE
LOWER MS VALLEY SATURDAY AFTERNOON...SFC DEWPOINTS IN THE 50S F AND
LIMITED INSTABILITY SHOULD INITIALLY LIMIT THE SEVERE POTENTIAL. AS
THE UPPER-LEVEL TROUGH CONTINUES ENEWD DURING THE OVERNIGHT
PERIOD... INCREASING MOISTURE ADVECTION ASSOCIATED WITH THE
LOW-LEVEL JET SHOULD RAISE SFC DEWPOINTS ACROSS SRN MS...SRN AL AND
THE FL PANHANDLE INTO THE LOW TO MID 60S F. THIS SHOULD INCREASE THE
POTENTIAL FOR SFC-BASED THUNDERSTORMS MAINLY IN THE 06 TO 12Z
TIMEFRAME. FORECAST SOUNDINGS FROM THE COAST OF MS EWD INTO THE FL
PANHANDLE SATURDAY NIGHT SHOW 0-6 KM SHEAR VALUES IN THE 55-65 KT
RANGE WITH STRONG LOW-LEVEL SHEAR AND LOOPED HODOGRAPHS. IN SPITE OF
RATHER WEAK INSTABILITY...THE SHEAR ENVIRONMENT SHOULD BE SUFFICIENT
FOR A FEW ROTATING STORMS WITH A MARGINAL TORNADO THREAT.
..BROYLES.. 11/20/2009
000
ACUS01 KWNS 201619
SWODY1
SPC AC 201617
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1017 AM CST FRI NOV 20 2009
VALID 201630Z - 211200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
WEAK LONGWAVE RIDGING WAS LOCATED OVER THE ROCKIES...WITH A BROAD
TROUGH MOVING EWD ACROSS THE CENTRAL PORTIONS OF THE COUNTRY. THE
ONLY CONVECTIVE AREA OF INTEREST FOR POSSIBLE SEVERE STORMS TODAY
WILL BE ASSOCIATED WITH AN EMBEDDED SHORTWAVE TROUGH LOCATED ON THE
SRN END OF THE LARGER SCALE TROUGH...OVER THE BIG BEND AREA OF
TEXAS.
...SRN TX...
AT MID MORNING...ELEVATED THUNDERSTORMS STRETCHED FROM NEAR SAT TO
LRD...AND APPEARED TO BE OCCURRING WITHIN REGION OF STRONGER FORCING
ALOFT. THESE STORMS ARE LIKELY TO INTENSIFY AS THEY SPREAD EWD
THROUGH THE DAY INTO A SLOWLY WARMING AND DESTABILIZING AIR MASS. AS
TEMPERATURES WARM INTO THE MID/UPPER 70S...STORMS MAY BECOME SURFACE
BASED BY MID AFTERNOON...ESPECIALLY ALONG AND EAST OF A NIR-MFE
LINE. MUCAPES BETWEEN 1000-2000 J/KG AND 30-40 KT DEEP LAYER SHEAR
MAY BE SUFFICIENT FOR AN ISOLATED SEVERE STORM OR TWO...WITH
MARGINAL SEVERE HAIL/WIND GUSTS. HOWEVER...SEVERE PROBABILITIES
REMAIN LOW DUE TO EXTENSIVE CLOUDS...WEAK WINDS IN THE LOWER 2-3 KM
AND STRONGER CONVECTION/INSTABILITY SITUATED EAST OF THE MAINLAND IN
THE WRN GULF.
..IMY/SMITH.. 11/20/2009
000
ACUS01 KWNS 201222
SWODY1
SPC AC 201221
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0621 AM CST FRI NOV 20 2009
VALID 201300Z - 211200Z
...NO SVR TSTM AREAS FORECAST...
...WRN GULF COAST...
UPR TROUGH CONTINUES EWD FROM NERN MEXICO INTO SRN TX TODAY AS
MID/UPR LEVEL WIND MAX TRANSLATES EWD INTO NWRN GULF OF MEXICO.
ONGOING STRONG LOW LEVEL WARM ADVECTION IS CONTINUING WIDESPREAD
CONVECTION ACROSS MUCH OF CENTRAL TX SWD OFFSHORE INTO NWRN GULF.
SURFACE LOW WILL GRADUALLY DEVELOP OFF THE CENTRAL TX COAST IN
RESPONSE AS INCREASINGLY FAVORABLE UPPER SUPPORT ARRIVES WITH THE
TROUGH AND MID/UPR JET.
WITH THE LOW OFFSHORE...MOST FAVORABLE AIR MASS IN SUPPORT OF A
SEVERE THREAT SHOULD ALSO REMAIN OVER THE NWRN GULF WATERS.
NEVERTHELESS THE STRONG ASCENT WITH THE UPPER TROUGH AND CONTINUED
ADVECTION OF THE VERY MOIST AIR MASS FROM THE WRN GULF WILL MAINTAIN
ACTIVE THUNDERSTORMS INLAND...SPREADING EWD ACROSS SERN TX TODAY AND
INTO SRN LA TONIGHT.
AS THE TROUGH PUSHES A COLD FRONT EWD ACROSS S TX THIS
AFTERNOON...THERE STILL IS POTENTIAL FOR A FEW STRONG/BRIEFLY SEVERE
THUNDERSTORMS. HOWEVER..OVERALL SHEAR AND LAPSE RATES LESS THAN
7C/KM WILL LIMIT THE THREAT AND ONLY LOW PROBS OF SVR WILL BE
MAINTAINED.
..HALES/JEWELL.. 11/20/2009
000
ACUS03 KWNS 200657
SWODY3
SPC AC 200656
DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1256 AM CST FRI NOV 20 2009
VALID 221200Z - 231200Z
...SYNOPSIS/FCST...
UPR LOW OVER THE TN VLY EARLY SUNDAY WILL DEAMPLIFY AND BECOME
ABSORBED INTO THE NRN STREAM OVER THE OH VLY BY NIGHTFALL. THE
RESULT WILL BE FOR WEAKENING LLVL WIND FIELDS/CONVERGENCE ALONG A
CDFNT/SFC LOW OVER NRN FL/ERN GULF OF MEXICO. WHILE A FEW TSTMS
WILL BE LIKELY OVER THE ERN GULF CSTL STATES EARLY SUNDAY...EXPECT
THAT ACTIVITY WILL WEAKEN WITH TIME AND WITH SEWD EXTENT. STREAMER
SHOWERS/ISOLD TSTMS MAY INCREASE DOWNSTREAM INTO FAR ERN NC/SC
SUNDAY NIGHT. HOWEVER...EXPECTED MEAGER BUOYANCY/LAPSE RATES WILL
PRECLUDE SVR TSTMS.
..RACY.. 11/20/2009
000
ACUS02 KWNS 200542
SWODY2
SPC AC 200541
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1141 PM CST THU NOV 19 2009
VALID 211200Z - 221200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
SPLIT FLOW REGIME WILL CONTINUE INTO THE WEEKEND. SRN STREAM UPR
TROUGH CURRENTLY MOVING INTO TX WILL SLOWLY TRANSLATE TO THE LWR MS
VLY BY EARLY SATURDAY...THEN BECOME NEGATIVELY-TILTED AS IT MOVES
ACROSS THE TN VLY SATURDAY NIGHT. IN THE NRN STREAM...A PARADE OF
STRONG DISTURBANCES WILL TRAVEL FROM THE NRN PAC BASIN INTO THE
INTERMOUNTAIN W AND NRN ROCKIES/PLAINS.
IN THE LWR LVLS...A LOW WILL INTENSIFY OVER THE LWR MS VLY EARLY
SATURDAY...THEN TRACK ENE INTO CNTRL AL BY 12Z SUNDAY. TO THE E OF
THE LOW...A MODIFIED CP AIR MASS WILL ADVECT NWD INTO THE ERN GULF
CSTL STATES WHILE A CDFNT/PRE-FNTL TROUGH ADVANCES FROM W-E ALONG
THE CST THROUGH THE DAY 2 PD.
...SERN LA TO FL PNHDL/NWRN FL...
CURRENT STREAMLINES DEPICT NLY LLVL FLOW CONTINUING OVER THE ERN
GULF OF MEXICO. TRAJECTORIES WILL VEER TO SLY LATE FRIDAY/SATURDAY
AS THE UPR LOW APCHS THE REGION AND A MODIFIED CP AIR MASS WILL
RETURN NWD BY SATURDAY EVE ACROSS SRN AL/GA AND THE FL PNHDL
/LWR-MID 60S SFC DEW POINTS/. THIS WILL RESULT IN GRADUAL
DESTABILIZATION...THOUGH LAPSE RATES WILL LIKELY REMAIN POOR IN THE
WARM SECTOR THROUGH SATURDAY NIGHT.
ELEVATED CONVECTION SHOULD INCREASE SATURDAY MORNING WELL-INLAND
WITH SFC-BASED TSTMS EVOLVING ALONG AN EWD MOVING PRE-FRONTAL TROUGH
FROM SERN LA INTO THE CNTRL GULF BASIN BY LATE MORNING. ACTIVITY
WILL PROGRESS ENE INTO PARTS OF THE ERN GULF STATES SATURDAY NIGHT.
MORE ROBUST TSTMS WILL CONTINUE TO REMAIN OFFSHORE. BUT...A FEW
SUSTAINED STG STORMS WILL PROBABLY MANAGE TO DEVELOP IN THE
NEARSHORE WATERS AND MOVE INLAND SATURDAY EVENING/NIGHT INTO SRN
PARTS OF AL/GA AND THE FL PNHDL/NWRN FL. PRESENCE OF SUBSTANTIAL
TURNING IN THE LOWEST 1-2 KM AMIDST 40-45 KTS OF 0-6KM SHEAR ALONG
THE MARINE FRONT WILL RESULT IN A NON-ZERO THREAT FOR ISOLD
SUPERCELLS WITH A RISK OF A BRIEF TORNADO.
..RACY.. 11/20/2009
000
ACUS01 KWNS 200526
SWODY1
SPC AC 200524
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1124 PM CST THU NOV 19 2009
VALID 201200Z - 211200Z
...NO SVR TSTM AREAS FORECAST...
...WESTERN GULF COAST...
POSITIVE TILTED UPPER TROUGH LOCATED OVER NM/WEST TX WILL GRADUALLY
SHIFT EAST ACROSS TX AS STRONGEST MID LEVEL FLOW...H5 SPEEDS ON THE
ORDER OF 50KT...ROTATES THROUGH THE BASE OF THE TROUGH INTO THE NWRN
GULF OF MEXICO. THIS LOW LATITUDE SPEED MAX WILL ENSURE THE PRIMARY
BAROCLINIC ZONE BECOMES ESTABLISHED OVER THE NRN GULF OF
MEXICO...CONSIDERABLY SOUTH OF THE LA COAST DURING THE LATTER HALF
OF THE PERIOD. PRIOR TO SFC CYCLOGENESIS OFF THE SOUTH TX COAST...A
CONSIDERABLE AMOUNT OF CONVECTION WILL LIKELY BE ONGOING WITHIN
MARGINALLY UNSTABLE AIRMASS OVER THE COASTAL PLAINS OF TX. SFC DEW
POINTS IN THE UPPER 60S TO AROUND 70F...AND OVERALL MOISTURE
CONTENT...HAVE RETURNED TO THE LOWER-MIDDLE TX COAST. THIS AIRMASS
WILL CONTRIBUTE TO SFC-BASED CONVECTION WITHIN A WARM ADVECTION
REGIME CAPABLE OF SUPPORTING WEAK SUPERCELL DEVELOPMENT. THERE
APPEARS TO BE AT LEAST A LOW PROBABILITY FOR ISOLATED HAIL/WIND OR
EVEN A TORNADO WITHIN THE STRONGEST SUPERCELLS...HOWEVER COVERAGE OF
SEVERE SHOULD PROVE INADEQUATE FOR A SLIGHT RISK.
...NEW ENGLAND...
FOCUSED HEIGHT FALLS ACROSS NEW ENGLAND WILL ENHANCE UVV ALONG/AHEAD
OF FRONTAL BOUNDARY AS IT PROGRESSES TOWARD THE COAST EARLY IN THE
PERIOD. FORECAST MID LEVEL LAPSE RATES SHOULD APPROACH 7 C/KM WHICH
WILL RESULT IN WEAK ELEVATED INSTABILITY SUFFICIENT FOR DEEP
CONVECTION CAPABLE OF GENERATING ISOLATED LIGHTNING. THUNDER THREAT
WILL END WITH PASSAGE OF COLD FRONT AND BE ENTIRELY OFFSHORE BY
21/00Z.
...PACIFIC NW...
VERY COLD MID LEVEL TROUGH WILL PROGRESS INLAND DURING THE DAY WITH
MID LEVEL TEMPERATURES AOB -30C ALONG THE COASTS OF WA/ORE/NRN CA BY
21/00Z. POST FRONTAL INSTABILITY SHOULD INCREASE WITHIN ONSHORE
FLOW BENEATH THIS TROUGH AND ISOLATED THUNDERSTORMS CAN BE EXPECTED
WHERE MARINE INFLUENCES ARE GREATEST.
..DARROW/GRAMS.. 11/20/2009
000
ACUS11 KWNS 200128
SWOMCD
SPC MCD 200128
TXZ000-200300-
MESOSCALE DISCUSSION 2179
NWS STORM PREDICTION CENTER NORMAN OK
0728 PM CST THU NOV 19 2009
AREAS AFFECTED...PARTS OF S TX AND THE LOWER TX COAST
CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY
VALID 200128Z - 200300Z
THE THREAT FOR ISOLATED SEVERE STORMS...INCLUDING EPISODIC SUPERCELL
STRUCTURES...IS EXPECTED TO CONTINUE ACROSS REGION TONIGHT. A WW IS
NOT CURRENTLY ANTICIPATED.
TSTMS CONTINUE TO INCREASE IN COVERAGE AND INTENSITY THIS EVENING
OVER THE LOWER TX COAST WITHIN STRENGTHENING WWA REGIME ASSOCIATED
WITH MIDLEVEL TROUGH APPROACHING FROM THE W. AS OF 0117Z...CRP
RADAR DATA INDICATED A STORM EXHIBITING SUPERCELL CHARACTERISTICS
OVER CORPUS CHRISTI BAY ALONG THE SRN FRINGE OF A LARGER COMPLEX OF
STORMS. AS MENTIONED IN 01Z OUTLOOK...AIR MASS IS RATHER MOIST
WHICH SHOULD MAINTAIN AT LEAST A MARGINALLY UNSTABLE ENVIRONMENT
OVERNIGHT WITH MLCAPE OF LESS THAN 1000 J/KG.
LATEST TRENDS IN CRP VWP DO INDICATE SOME INCREASE IN LOW-LEVEL
WINDS WHICH IS RESULTING IN AN ENVIRONMENT FAVORABLE FOR UPDRAFT
ROTATION. AS SUCH...THE POTENTIAL WILL EXIST FOR TRANSIENT
SUPERCELL STRUCTURES CAPABLE OF ISOLATED SEVERE WEATHER. IT APPEARS
THAT A MORE WIDESPREAD SEVERE WEATHER EPISODE WILL LIKELY BE LIMITED
BY THE WEAK LOW-LEVEL LAPSE RATES AND MARGINAL CONVECTIVE
INSTABILITY...AND THUS A WW IS NOT CURRENTLY ANTICIPATED.
..MEAD.. 11/20/2009
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...HGX...CRP...EWX...BRO...
LAT...LON 27279724 27169817 27929850 28849834 29249781 29279712
29069644 28529609 27759650 27279724
000
ACUS01 KWNS 200038
SWODY1
SPC AC 200036
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0636 PM CST THU NOV 19 2009
VALID 200100Z - 201200Z
...NO SVR TSTM AREAS FORECAST...
...TX...
LOW LEVEL WARM ADVECTION IS BEGINNING TO INTENSIFY ACROSS SOUTH
TX...PER RECENT INCREASE IN THUNDERSTORM ACTIVITY ALONG THE
MIDDLE/LOWER TX COAST. THIS ACTIVITY SHOULD ONLY INCREASE THROUGH
THE OVERNIGHT HOURS AS APPROACHING SHORTWAVE TROUGH ENHANCES
VERTICAL ASCENT ACROSS THE OUTLOOK REGION. 00Z SOUNDINGS FROM CRP
AND BRO HAVE MOISTENED SIGNIFICANTLY WITH PWAT VALUES ON THE ORDER
OF 1.5-1.7 INCHES. VERTICAL SHEAR IS NOT PARTICULARLY
STRONG...THOUGH VEERING WINDS DO INCREASE WITH HEIGHT SUGGESTING
WEAK SUPERCELLS COULD EVOLVE WITHIN THE EXPANDING THUNDERSTORM
CLUSTERS. GIVEN THAT LAPSE RATES ARE MARGINALLY STEEP IT APPEARS
ANY SEVERE HAIL THAT ACCOMPANIES THE STRONGER UPDRAFTS WILL BE
ISOLATED IN NATURE. IN ADDITION...WITH THE SFC DEW POINTS NOW
RISING THROUGH THE UPPER 60S TO NEAR 70 F SFC BASED SUPERCELLS COULD
POSE AT LEAST A LOW THREAT FOR TORNADOES. FOR THIS REASON HAVE
INCLUDED 2 PERCENT TORNADO PROBS IN THE 01Z OUTLOOK.
...ELSEWHERE...
STRONGEST ZONE OF WARM ADVECTION/CONVECTION IS LIFTING NNEWD ACROSS
PA INTO SRN NY. OTHER MORE DISCRETE UPDRAFTS HAVE RECENTLY EVOLVED
OVER SRN VA/NC. WITH STRONGER FORCING EXPECTED TO SPREAD AWAY FROM
MORE BUOYANT AIRMASS IT APPEARS SRN-MOST ACTIVITY WILL BE QUITE
ISOLATED THE REST OF THE TONIGHT.
..DARROW.. 11/20/2009
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