MESOSCALE DISCUSSION 2064
   NWS STORM PREDICTION CENTER NORMAN OK
   0625 PM CDT FRI AUG 20 2004
   
   AREAS AFFECTED...W-CENTRAL AND SWRN TX
   
   CONCERNING...HEAVY RAINFALL...SEVERE THUNDERSTORM WATCH 769...
   
   VALID 202325Z - 210100Z
   
   SEVERE THUNDERSTORM WATCH 769 CONTINUES ACROSS PORTIONS OF W-CENTRAL
   AND SWRN TX. A LOCALIZED HEAVY RAINFALL EVENT...WITH RATES 2-3"/HR
   ...IS EXPECTED THROUGH 01Z ACROSS TOM GREEN...CONCHO...MENARD...AND
   NERN SCHLEICHER COUNTIES. 
   
   AT 2315Z...SMALL BUT INTENSE THUNDERSTORM CLUSTER REMAINS ANCHORED
   ALONG STATIONARY LARGE-SCALE OUTFLOW BOUNDARY JUST SOUTH AND EAST OF
   SJT. LOW-LEVEL CONVERGENCE COUPLED WITH MLCAPE VALUES OF 3000-3500
   J/KG SHOULD MAINTAIN STORMS FOR AT LEAST 1-2 ADDITIONAL HOURS. SJT
   VAD INDICATES SFC-6KM SHEAR OF 40 KT JUST NORTH OF THE OUTFLOW
   BOUNDARY. THIS SHOULD CONTINUE TO FAVOR LONG-LIVED CELLS...WITH
   POTENTIAL FOR LARGE HAIL. ADDITIONALLY...SLOW STORM MOTIONS AND PW
   VALUES IN EXCESS OF 1.5 IN WILL MAINTAIN THREAT OF VERY HEAVY
   RAINFALL ACROSS ABOVE MENTIONED COUNTIES THROUGH 01Z. SATELLITE
   TRENDS SUGGEST ISOLATED SEVERE THUNDERSTORMS ARE POSSIBLE NEAR THE
   BOUNDARY BETWEEN SJT AND MAF DURING NEXT COUPLE OF HOURS. INCREASING
   CIN AND WEAK UPPER FORCING SHOULD LIMIT THUNDERSTORM DEVELOPMENT
   AWAY FROM THE OUTFLOW BOUNDARY AS NEAR SURFACE AIR MASS BEGINS TO
   COOL THIS EVENING.
   
   ..BANACOS.. 08/20/2004
   
   
   ATTN...WFO...EWX...SJT...MAF...
   
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