MESO: Mesoscale Discussion 2131

ACUS11 KWNS 041909
SWOMCD
SPC MCD 041908
TXZ000-042115-

MESOSCALE DISCUSSION 2131
NWS STORM PREDICTION CENTER NORMAN OK
0108 PM CST TUE DEC 04 2012

AREAS AFFECTED...TX COASTAL PLAIN

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 041908Z - 042115Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...A SMALL SEVERE TSTM WATCH MAY BE CONSIDERED FOR PARTS OF
THE TX COASTAL PLAIN THIS AFTERNOON-EVENING. ISOLD LARGE HAIL AND A
FEW INSTANCES OF STRONG-SEVERE WIND GUSTS ARE POSSIBLE THRU THE
EARLY EVENING.

DISCUSSION...TRENDS IN VISIBLE SATELLITE IMAGERY SHOW A SWELLING CU
FIELD INVOF A PRE-FRONTAL WINDSHIFT AND OVER A WARM SECTOR LOCATED
OVER THE TX COASTAL PLAIN. SURFACE TEMPS HAVE WARMED INTO THE LOWER
80S AMIDST AN ADEQUATELY MOIST/DESTABILIZING AIRMASS. A MID-LEVEL
SPEED MAX IS CONTINUING TO APPROACH THE REGION FROM THE CONCHO RIVER
VALLEY/EDWARDS PLATEAU REGION. UPWARD VERTICAL MOTION ASSOCIATED
WITH THE UPPER FEATURE...COMBINED WITH WEAK LOW LEVEL CONFLUENCE
ALONG THE PREFRONTAL BOUNDARY...AND DIABATIC HEATING WILL ACT TO
FURTHER WEAKEN THE CAP SAMPLED BY THE 12Z CRP RAOB. THE CAP HAS
ALREADY ERODED FROM MATAGORDA BAY NEWD TO THE SABINE RIVER...WITH
SCTD STORMS /OCCASIONAL PULSATING SEVERE UPDRAFT/ EXPECTED TO LEAD
TO SUBSTANTIAL CONVECTIVE OVERTURNING OVER THE NEXT FEW
HRS...THEREBY LESSENING THE SEVERE RISK IN THIS REGION. FARTHER
SSW...MORE SPARSE CONVECTIVE COVERAGE --LIKELY DELAYED UNTIL
MID-LATE AFTERNOON-- IS EXPECTED. UPWARDS OF 40 KT DEEP SHEAR AND A
MODERATELY UNSTABLE AIRMASS /1500 J/KG MLCAPE/ WILL SUPPORT
ORGANIZED STORM STRUCTURES CAPABLE OF ISOLD LARGE HAIL/DMGG WIND
GUSTS.

..SMITH/MEAD.. 12/04/2012

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...HGX...CRP...EWX...BRO...

LAT...LON 27199742 26789801 27619907 28629874 29919674 30099507
29359469 28019688 27199742

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