MESO: Mesoscale Discussion 0003

ACUS11 KWNS 082154
SWOMCD
SPC MCD 082153
TXZ000-090030-

MESOSCALE DISCUSSION 0003
NWS STORM PREDICTION CENTER NORMAN OK
0353 PM CST TUE JAN 08 2013

AREAS AFFECTED...PORTIONS S AND SW TX INVOF RIO GRANDE VALLEY...EWD
ROUGHLY TO JCT-SAT-MFE LINE.

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 082153Z - 090030Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...THROUGH REMAINDER AFTERNOON INTO EARLY EVENING -- I.E.
THROUGH 03Z -- CONDITIONS ARE EXPECTED TO BECOME MORE FAVORABLE FOR
SVR OVER OUTLINED AREA ALONG AND E OF RIO GRANDE VALLEY. ONSET
TIMING OF SFC-BASED SVR RISK OVER MAINLY DEEP S TX REMAINS
UNCERTAIN...BUT WW MAY BE REQUIRED IN NEXT COUPLE OF HOURS.

DISCUSSION...SFC MESOANALYSIS INDICATES LOW INVOF NRN ZAPATA
COUNTY...WITH WAVY WARM FRONT EWD OVER BROOKS COUNTY...NEWD TO NEAR
BYY...THEN EWD OVER WATERS OFFSHORE GLS. QUASISTATIONARY FRONTAL
ZONE EXTENDS SWWD INTO DEEPER LOW OVER HIGH TERRAIN OF NRN MEX.
AREAS OF LOW PRESSURE SHOULD BLEND GRADUALLY AS MID-UPPER LEVEL
CYCLONE PIVOTS EWD FROM ITS LATEST POSITION ABOUT 250 NM S ELP.
CONSIDERABLE PRECIP OVER GULF HAS DIFFUSED TX COASTAL FRONTAL ZONE
SOMEWHAT...WITH PUREST MARITIME/TROPICAL AIR LOCATED WELL OUT OVER
OPEN GULF S OF OUTFLOW BOUNDARIES. STILL...BROAD/STRENGTHENING LLJ
IS EXPECTED TO CONTRIBUTE TO SHALLOWER AND LESS STABLE BOUNDARY
LAYER N OF FRONT WITH TIME...WHILE THETAE ADVECTION INCREASES
BUOYANCY ON BOTH SIDES OF FRONT. DEEP SHEAR WILL STRENGTHEN WITH
APCH OF CYCLONE ALOFT...INCREASING ORGANIZED CONVECTIVE/SVR THREAT
WITH ACTIVITY MOVING NEWD OUT OF CURRENT TSTM GENESIS REGION OVER
MEX PLATEAU. STG CAPPING HAS BEEN EVIDENT IN 12Z MONTERREY SOUNDING
AS WELL AS SEVERAL MODEL FCST SOUNDINGS ACROSS S TX AHEAD OF MEX
CONVECTION...INDICATING LOW PROBABILITY OF DEVELOPMENT NEAR SFC LOW
OR FRONT PRIOR TO ARRIVAL OF STRONGER LARGE-SCALE LIFT RELATED TO
CYCLONE ALOFT.

DAYLONG PERSISTENCE OF LOW-CLOUD COVER AND RELATED STABILIZING
EFFECTS SUGGEST SOME DELAY IN SFC-BASED SVR POTENTIAL WITH
CONVECTION MOVING NEWD OUT OF MEX. ACTIVITY IS EXPECTED TO STAY
ELEVATED OVER NRN PORTIONS OF THIS AREA...WITH MAIN CONCERN BEING
MRGL SVR HAIL AND OCNL STG GUSTS. HOWEVER...EROSION OF STABLE LAYER
OVER DEEP S TX...COMBINED WITH INCREASINGLY INTENSE QLCS-MODE
ORGANIZATION THIS EVENING...SHOULD LEAD TO GRADUAL INCREASE IN WIND
THREAT WITH TIME.

..EDWARDS/MEAD.. 01/08/2013

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

ATTN...WFO...CRP...EWX...BRO...SJT...

LAT...LON 29780050 30020013 30459966 30379896 29979870 29329849
26219853 26239868 26369880 26379909 26499911 26549919
26839926 26909938 27009938 27029946 27259947 27299954
27379944 27519949 27629957 27659970 27829988 28140008
28260028 28510038 29140067 29150079 29240077 29780050

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