SPC AC 211955
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0155 PM CST THU DEC 21 2006
VALID 212000Z - 221200Z
...THERE IS A SLGT RISK OF SVR TSTMS OVER THE TX COASTAL PLAIN TO
LOWER MS VALLEY....
...TX COASTAL PLAIN TO LOWER MS VALLEY...
SLOW MOVING DEEP AND COLD MID/UPPER LEVEL LOW WILL CONTINUE TO TRACK
NE TOWARD IA/MO THIS FORECAST PERIOD. STRONG MID LEVEL JET /80 KT/
WILL CONTINUE TO TRANSLATE THROUGH SERN/ERN PERIPHERIES OF UPPER
LOW...WHILE SRN STREAM FLOW PERSISTS FROM MEXICO ACROSS DEEP S TX
INTO THE GULF OF MEXICO. GEOMETRY OF MID/UPPER LEVEL JETS WILL
MAINTAIN FAVORABLE REGION OF LARGE SCALE ASCENT OVER THE TX COASTAL
PLAIN AND WRN GULF INTO THE LOWER MS VALLEY.
AT THE SURFACE...OCCLUDED LOW LOCATED OVER NORTH CENTRAL KS EARLY
THIS AFTERNOON WILL TRACK SLOWLY NEWD...WHILE SECONDARY LOW MOVES
NWD THROUGH WRN IL. COLD FRONT TRAILING SSWWD FROM SECONDARY LOW
THROUGH FAR NW MS AND SW LA TO ANOTHER SMALL AREA OF LOW PRESSURE
LOCATED JUST OFFSHORE OF THE S TX COAST. THIS FRONT SHOULD BE
NEARLY STATIONARY INTO THE EVENING WITH A SLOW EWD MOVEMENT LATER IN
THE FORECAST PERIOD AS BOUNDARY REMAINS PARALLEL TO SWLY FLOW ALOFT.
MEANWHILE...MESOANALYSES SUGGEST A WEAK ZONE OF LOW LEVEL
CONVERGENCE LOCATED 50-60 MILES INLAND ALONG THE TX COASTAL PLAIN...
AND A WEAK COASTAL BOUNDARY EXTENDED EWD ACROSS THE FAR NRN GULF
INCLUDING ACROSS SERN LA.
INCREASING ASCENT AHEAD OF SRN STREAM IMPULSE...NOW MOVING INTO DEEP
S TX PER WATER VAPOR IMAGERY...AND STEEPENING MID LEVEL LAPSE RATES
WILL SUPPORT ADDITIONAL TSTM DEVELOPMENT THIS AFTERNOON INTO THE
EVENING ACROSS THE TX COASTAL PLAIN TO PARTS OF SWRN LA. LARGE HAIL
AND DAMAGING WIND GUSTS ARE EXPECTED TO BE THE PRIMARY THREATS WITH
THIS ACTIVITY. FARTHER NE ACROSS THE LOWER MS VALLEY...EXTENSIVE
AREA OF CLOUDS/PRECIPITATION IS LIMITING INLAND DESTABILIZATION TO
THE NORTH OF THE COASTAL BOUNDARY OVER THE NRN GULF. WEAK
INSTABILITY AND 40-50 KT OF EFFECTIVE BULK SHEAR IN THE VICINITY OF
THIS BOUNDARY SHOULD SUPPORT A FEW ORGANIZED STORMS THIS AFTERNOON.
ADDITIONAL THREAT FOR TSTMS AND ATTENDANT SEVERE POTENTIAL IS
EXPECTED THIS EVENING/OVERNIGHT AS ASCENT INCREASES OVER THE LOWER
MS VALLEY AHEAD OF THE APPROACHING DEEP S TX SHORT WAVE TROUGH.
..PETERS.. 12/21/2006
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z
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