MESOSCALE DISCUSSION 0512
   NWS STORM PREDICTION CENTER NORMAN OK
   1052 AM CDT SAT APR 18 2009
   
   AREAS AFFECTED...PORTIONS S-CENTRAL/SE TX.
   
   CONCERNING...SEVERE THUNDERSTORM WATCH 164...
   
   VALID 181552Z - 181645Z
   
   THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 164
   CONTINUES.
   
   WW SCHEDULED TO EXPIRE AT 16Z.  ADDITIONAL WW ISSUANCE MAY BE
   REQUIRED.
   
   EARLIER AND MORE DENSELY ORGANIZED MCS HAS EVOLVED INTO BKN/EMBEDDED
   TSTMS WITHIN BROADER PRECIP AREA...MOST OF WHICH EXTENDS ACROSS
   PORTIONS WW 165...THEN TRAILING SWWD OVER
   KARNES/WILSON/DEWITT/GONZALES COUNTIES.  LOW LEVEL VERTICAL SHEAR
   STRENGTHENS WITH EWD EXTENT ACROSS WW AREA AND OVER SE TX...AND FROM
   CENTRAL TX EWD TO E TX...IN CLOSER PROXIMITY TO 40-50 KT LLJ THAT IS
   ENLARGING 0-1 KM AGL HODOGRAPHS.  ALTHOUGH LOW LEVEL SHEAR SHOULD
   CONTINUE TO DIMINISH WITH WWD EXTENT OVER THIS REGION...DEEP-LAYER
   WINDS WILL REMAIN FAVORABLE FOR SVR POTENTIAL...WITH EFFECTIVE SHEAR
   MAGNITUDES REMAINING IN 40-50 KT RANGE.
   
   SFC MESOANALYSIS SHOWS WEAK/RESIDUAL/QUASISTATIONARY FRONTAL ZONE
   FROM OFFSHORE LA WNWWD ACROSS MIDDLE TX COAST...AND DIFFUSE OUTFLOW
   BOUNDARY ROUGHLY FROM HOU-VCT-COT.  MODIFIED SOUNDINGS SUGGEST
   SBCINH CONTINUES TO WEAKEN ALONG AND 40-80 NM N OF THESE BOUNDARIES
   WITH COMBINATION OF SLOW DIABATIC HEATING AND SFC WAA...DESPITE
   PRESENCE OF PRECIP.  ADDITIONAL DESTABILIZATION IS EXPECTED ALONG/S
   OF BOUNDARIES...AND ALSO WILL BE GRADUAL BECAUSE OF EXTENSIVE CLOUD
   COVER NOTED IN VIS IMAGERY.  EXPECT MLCAPE TO RISE INTO 1500-2000
   J/KG RANGE THROUGH EARLY AFTERNOON S OF ONGOING CONVECTION. 
   CONFLUENCE LINE AND COLLOCATED SFC TROUGH ARE EVIDENT FROM COT AREA
   SSWWD TO JUST E OF LRD TOWARD MONTERREY MEX...WITH LITTLE MOVEMENT
   EXPECTED NEXT FEW HOURS.  W OF THIS LINE...NLY FLOW PREVAILS...AND
   BULK OF CONVECTION SHOULD REMAIN TO ITS E.  SRN EXTENT OF CONVECTIVE
   DEVELOPMENT ACROSS THIS AREA WILL BE LIMITED BY COMBINATION OF
   STRONGER CAPPING PER CRP/BRO RAOBS...AND LACK OF SIGNIFICANT LIFT S
   OF AFOREMENTIONED BOUNDARIES.
   
   ..EDWARDS.. 04/18/2009
   
   
   ATTN...WFO...HGX...CRP...EWX...BRO...
   
   LAT...LON   27609954 28539897 29959731 30109679 29999662 29679685
               29289657 29049690 28379641 28019687 27639719 27229737
               27289945 27609954