ZCZC SPCSWOMCD ALL
ACUS11 KWNS 031259 
SPC MCD 031259 
TXZ000-031430-

MESOSCALE DISCUSSION 0382
NWS STORM PREDICTION CENTER NORMAN OK
0759 AM CDT WED APR 03 2013

AREAS AFFECTED...PORTIONS S TX.

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

VALID 031259Z - 031430Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...LARGE/ISOLATED STG-SVR TSTM AND LIKELY SUPERCELL STILL
OVER MEX AS OF 1245Z MAY PERSIST IN ITS PROJECTED PATH ACROSS RIO
GRANDE AT LEAST INTO PORTIONS ZAPATA/STARR/SWRN JIM HOGG COUNTIES. 
MAIN THREAT IS LARGE HAIL...THOUGH STG/ISOLATED SVR GUSTS ARE
POSSIBLE.  ISOLATED SVR HAIL ALSO MAY OCCUR WITH ELEVATED CONVECTION
UPRIVER IN RIO GRANDE VALLEY...NNEWD ACROSS SRN HILL COUNTRY.

DISCUSSION...SFC MESOANALYSIS SHOWS COLD FRONT EXTENDING FROM LOW
OVER NWRN GULF...WSWWD ACROSS TX COAST NEAR MANSFIELD CUT...THEN
NWWD ACROSS ZAPATA COUNTY AND OVER ADJOINING PORTIONS MEX.  THIS
FRONT DELIMITS NRN BOUND OF MARITIME/TROPICAL AIR MASS WHERE SFC DEW
POINTS UPPER 60S F...BENEATH STEEP MIDLEVEL LAPSE RATES ASSOCIATED
WITH EML..SUPPORT MLCAPE 1500-2500 J/KG AND MUCAPE 2500-4000 J/KG. 
35-45 KT EFFECTIVE SHEAR MAGNITUDES ALSO ARE EVIDENT ALONG AND S OF
FRONT.  COLD FRONT IS PROGRESSIVE AND MAY UNDERCUT CONVECTION
CROSSING RIO GRANDE.  HOWEVER...FOR NOW...SWD COMPONENT OF RIGHTWARD
DEVIANCE OF TSTM IS CLOSE TO THAT OF FRONTAL MOTION.  THIS INDICATED
APPARENT SUPERCELL MAY INTERACT WITH FRONT WHILE STILL ACCESSING
WARM SECTOR...AND ALSO...ACCESSING ENHANCED LIFT THAT MAY BE
NECESSARY TO MAINTAIN CONVECTION IN FACE OF STG CAP SAMPLED BY BRO
RAOB.

ADDITIONAL DEVELOPMENT HAS BEEN NOTED IN ZONE OF ELEVATED LOW-LEVEL
WAA AND ISENTROPIC SCANT...ATOP FRONTAL SFC...FROM SERRANIAS DEL
BURRO RANGE OF NRN COAHUILA EWD TO RIO GRANDE AND NWWD TO JCT AREA. 
ISOLATED HAIL NEAR SVR LEVELS CANNOT BE RULED OUT...GIVEN 1500-200
J/KG ELEVATED MUCAPE EVIDENT IN 12Z DRT RAOB WITH 45-50 KT EFFECTIVE
SHEAR MAGNITUDES.  WEAKNESS OF BUOYANCY ALOFT SUGGESTS ORGANIZED SVR
THREAT IS MINIMAL.

..EDWARDS/KERR.. 04/03/2013

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

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

LAT...LON   26059813 26239862 26409910 26829927 27079949 27469946
            27819992 28670045 29170069 29460100 30450050 30919925
            30609831 29589803 28469841 27529919 27179901 26699820
            26059813 

NNNN