SWODY1
SPC AC 180556
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1156 PM CST FRI FEB 17 2012
VALID 181200Z - 191200Z
...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS SE TX TO SWRN GA....
...SYNOPSIS...
HEIGHTS ALOFT ARE FCST TO FALL OVER MOST OF WRN CONUS AS
SYNOPTIC-SCALE TROUGHING DEVELOPS THERE. STG MID-UPPER LEVEL
SHORTWAVE TROUGH -- NOW EVIDENT IN MOISTURE CHANNEL IMAGERY FROM
S-CENTRAL NM AND FAR W TX SWD ACROSS NWRN MEX -- IS EXPECTED TO
ACCELERATE ENEWD THIS PERIOD. BY 19/00Z...TROUGH SHOULD BE LOCATED
CLOSE TO I-35 IN TX...WITH SECONDARY/NRN STREAM PERTURBATION FARTHER
N OVER CENTRAL/ERN NEB AND NRN KS. DURING LATTER HALF OF
PERIOD...CENTRAL PLAINS PERTURBATION SHOULD MOVE SEWD OVER LOWER MO
VALLEY...WHILE SRN-STREAM SHORTWAVE TROUGH ACCELERATES AND
DEAMPLIFIES...REACHING PORTIONS MS/AL.
AT SFC...LEE-SIDE CYCLONE IS DEVELOPING OVER DEEP S TX/LOWER RIO
GRANDE VALLEY REGION ATTM...WITH APCH OF MID-UPPER WAVE. THIS
CYCLONE IS FCST TO DEEPEN THROUGH MOST OF PERIOD. LOW SHOULD CROSS
EXTREME SE TX/SWRN LA COASTAL AREAS AROUND 19/00Z...AT WHICH TIME
COLD FRONT SHOULD ARC SEWD OFFSHORE LA COAST...WITH WARM FRONT EWD
CLOSE TO MS/AL COAST. WARM FRONT SHOULD MOVE INLAND
OVERNIGHT...OVER PORTIONS SRN AL AND SRN GA. NOCTURNAL AIR MASS S
OF WARM FRONT OVER S-CENTRAL/SERN GA WILL BE RELATIVELY DEPRIVED OF
HIGHER THETAE FOUND FARTHER W...BECAUSE OF OVERLAND TRAJECTORIES
FROM FL. MEANWHILE SFC CYCLONE SHOULD MOVE TO CENTRAL AL BY END OF
PERIOD...ITS INLAND COMPONENT OF MOTION LIKELY OUTPACING THAT OF
FAVORABLE GULF AIR MASS FARTHER SE ACROSS SERN AL...FL PANHANDLE AND
SWRN GA.
...PORTIONS GULF-COAST STATES AND SWRN GA...
AS SO OFTEN HAPPENS FOR COOL-SEASON/GULF-COAST
SCENARIOS...LOW-CAPE/STRONG-SHEAR SVR EVENT IS FCST. PREDOMINANT
MODE SHOULD BE QUASI-LINEAR ALONG/AHEAD OF SFC COLD FRONT...ALTHOUGH
DISCRETE OR CLUSTERED SUPERCELLS MAY FORM AHEAD OF PRIMARY
CONVECTIVE BAND. DAMAGING GUSTS SHOULD BE MOST COMMON SVR
EVENT...WITH ISOLATED INSTANCES OF SVR HAIL AND A FEW TORNADOES
POSSIBLE.
INLAND PENETRATION OF WARM FRONT WILL BE MITIGATED BY PRESENCE OF
ABUNDANT CLOUDS/PRECIP TO ITS N...THEREFORE...THERE STILL IS
CONSIDERABLE UNCERTAINTY HOW FAR INLAND TO PROG FAVORABLE THETAE FOR
SFC-BASED EFFECTIVE PARCELS. AS SUCH...UNCONDITIONAL SVR
PROBABILITIES DIMINISH WITH NWD/NEWD EXTENT...AND ARE SHUNTED
SWD/SWWD COMPARED TO PREVIOUS OUTLOOKS VALID THIS PERIOD. STG-SVR
TSTMS MAY BE ONGOING ON EITHER SIDE OF WARM FRONT/SFC LOW EARLY IN
PERIOD OVER SE TX...WITH MULTIPLE CONVECTIVE EPISODES POSSIBLE AS
REGIME SHIFTS EWD ACROSS GULF-COAST CORRIDOR.
EVENING/OVERNIGHT WARM SECTOR NEAR CENTRAL-ERN GULF COAST SHOULD BE
CHARACTERIZED BY DEW POINTS MID-UPPER 60S F...OFFSETTING WEAK LAPSE
RATES ALOFT TO YIELD 500-1000 J/KG MLCAPE NEAR COAST..WEAKENING
MARKEDLY INLAND. 45-55 KT EFFECTIVE SHEAR MAGNITUDES AND 300-500
J/KG EFFECTIVE SRH...ALONG AND S OF WARM FRONT...WILL SUPPORT
CONDITIONAL SUPERCELL POTENTIAL IN WARM SECTOR...COVERAGE BEING MAIN
QUESTION. BOWS AND PERHAPS EMBEDDED SUPERCELLS ARE POSSIBLE WITHIN
MAIN CONVECTIVE BAND...WHERE RELATIVELY VEERED FLOW WILL RENDER WIND
PROFILES MORE UNIDIRECTIONAL THAN FARTHER E.
..EDWARDS/DEAN.. 02/18/2012
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