MESOSCALE DISCUSSION 0495
   NWS STORM PREDICTION CENTER NORMAN OK
   0547 PM CDT WED APR 20 2011
   
   AREAS AFFECTED...CNTRL TX
   
   CONCERNING...SEVERE THUNDERSTORM WATCH 171...
   
   VALID 202247Z - 202345Z
   
   THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 171
   CONTINUES.
   
   ONGOING CLUSTER OF THUNDERSTORMS ACROSS CNTRL TX CONTINUES TO
   DISPLAY THE POTENTIAL FOR PRODUCING LARGE HAIL AND DAMAGING WIND
   GUSTS...AND PERHAPS AN ISOLATED TORNADO. MIDLEVEL ROTATION HAS BEEN
   OBSERVED IN MANY OF THESE STORMS...WITH SEVERAL LEFT SPLITTING
   STORMS PROGRESSING NWD INTO A MORE STABLE ENVIRONMENT...EVIDENT IN
   WEAKENING RADAR REFLECTIVITY TRENDS WITH STORMS OVER COLEMAN/TOM
   GREEN COUNTIES OVER THE PAST 1-2 HRS. LATEST SFC SUBJECTIVE ANALYSIS
   PLACES A WEAK SFC LOW JUST W OF JCT...WITH EFFECTIVE FRONT SLOWLY
   SHIFTING SWD...REINFORCED BY THUNDERSTORM OUTFLOW. LOW-LEVEL
   CONVERGENCE WILL CONTINUE TO BE MAXIMIZED IN THE VICINITY OF THE SFC
   LOW AND ALONG THE COLD FRONT...WHICH SHOULD FOCUS ADDITIONAL
   THUNDERSTORM DEVELOPMENT...WHILE THUNDERSTORMS N OF THE FRONT REMAIN
   DRIVEN MAINLY BY BOUNDARY INTERACTIONS. THE THREAT FOR LARGE HAIL
   AND DAMAGING WINDS WILL LIKELY CONTINUE INTO THIS EVENING...THOUGH
   THUNDERSTORM ACTIVITY SHOULD DIMINISH WITH TIME WITH THE ONSET OF
   DIABATIC COOLING.
   
   FARTHER E...WEAK LOW-LEVEL CONVERGENCE ALONG THE NEARLY STATIONARY
   FRONT HAS FAILED TO INITIATE CONVECTION...UNABLE TO OVERCOME WEAK
   CINH AS THUNDERSTORM ANVILS HAVE SPREAD OVERHEAD. WITH THE LOSS OF
   DIABATIC HEATING...IT APPEARS THAT THE POTENTIAL FOR ANY
   THUNDERSTORM DEVELOPMENT WILL REMAIN LOW INTO THE LATE EVENING.
   
   ..ROGERS.. 04/20/2011
   
   
   ATTN...WFO...FWD...EWX...SJT...MAF...
   
   LAT...LON   29400172 31140173 31979805 30259803 29400172