MESO: Mesoscale Discussion 1945

ACUS11 KWNS 121955
SWOMCD
SPC MCD 121955
LAZ000-TXZ000-122200-

MESOSCALE DISCUSSION 1945
NWS STORM PREDICTION CENTER NORMAN OK
0255 PM CDT WED SEP 12 2012

AREAS AFFECTED...PORTIONS OF THE MIDDLE/UPPER TX COASTAL PLAIN AND
SWRN LA

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 121955Z - 122200Z

PROBABILITY OF WATCH ISSUANCE...5 PERCENT

SUMMARY...A FEW THUNDERSTORMS COULD PRODUCE SVR WIND GUSTS ON A VERY
ISOLATED BASIS THIS AFTERNOON...AND THE ISSUANCE OF A WW IS NOT
NEEDED.

DISCUSSION...VISIBLE SATELLITE IMAGERY DEPICTS A COMPOSITE
OUTFLOW/SEA BREEZE BOUNDARY WITHIN THE ZONE OF RELATIVELY RICH
MOISTURE THAT LIES SOUTH OF A MARINE-LAYER FRONT. AS CONVECTION
REGENERATES PROGRESSIVELY INLAND INVOF THE COMPOSITE
BOUNDARY...INFLOW WILL BE CHARACTERIZED BY 1500-2500 J/KG OF MLCAPE
PER MODIFIED 12Z RAOBS AS TEMPERATURES HAVE CLIMBED INTO THE LOWER
90S WITH DEWPOINTS HAVING MIXED OUT INTO THE MIDDLE 60S TO THE LOWER
70S. THIS WILL SUPPORT A FEW INTENSE STORMS WHERE CONVECTIVE
OVERTURNING HAS NOT YET TAKEN PLACE...WHILE STEEP LOW-LEVEL LAPSE
RATES AND DCAPE OF 1000 TO 1300 J/KG ENHANCE DOWNDRAFT STRENGTH. AS
SUCH...A VERY ISOLATED SVR WIND THREAT WILL EXIST THIS AFTERNOON --
IF STORMS CAN BE MAINTAINED ALONG THE COMPOSITE BOUNDARY.
HOWEVER...WITH 0-6-KM BULK SHEAR MAGNITUDES AOB 20 KT PER REGIONAL
VWP DATA...THE THREAT FOR STORM ORGANIZATION... PERSISTENCE...AND
STRENGTH WILL BE LIMITED.

..COHEN/PETERS.. 09/12/2012

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

ATTN...WFO...LCH...SHV...HGX...FWD...EWX...

LAT...LON 31449472 31129316 30499225 30179207 30009242 30069316
30319381 30639429 30749472 30679503 30399525 30059544
29579607 29379665 29239717 29279762 29599766 29879763
30549712 31089620 31449472

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