MESOSCALE DISCUSSION 2034
   NWS STORM PREDICTION CENTER NORMAN OK
   0523 PM CDT SAT SEP 26 2009
   
   AREAS AFFECTED...SRN IL...WRN KY AND SRN IND
   
   CONCERNING...SEVERE THUNDERSTORM WATCH 744...
   
   VALID 262223Z - 270000Z
   
   THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 744
   CONTINUES.
   
   THREAT FOR ISOLATED DAMAGING WIND AND LARGE HAIL WILL PERSIST
   THROUGH THE EARLY EVENING OVER EXTREME SRN IL...SRN IND AND WRN KY.
   SOME THREAT FOR SEVERE WEATHER EXISTS WITH STORMS DEVELOPING EAST OF
   WW 744 ACROSS W CNTRL KY AND SRN IND...BUT THREAT IN THESE AREAS
   WILL PROBABLY REMAIN TOO LIMITED IN DURATION FOR ANOTHER WW
   ISSUANCE.
   
   EARLY THIS EVENING A LINE OF THUNDERSTORMS WITH OCCASIONAL EMBEDDED
   ROTATING UPDRAFTS EXTENDS FROM SWRN IND SWWD TO NEAR THE KY-IL
   BORDER MOVING ESE AT AROUND 30 KT. OVERALL TREND HAS BEEN FOR STORMS
   TO UNDERGO A DECREASE IN INTENSITY. SRN PORTION OF THE LINE APPEARS
   TO HAVE BECOME OUTFLOW DOMINANT WITH AN EXTENSIVE OUTFLOW BOUNDARY
   EVIDENT ON RADAR JUST AHEAD OF THE STRONGER CORES. THE LINE IS
   CURRENTLY MOVING THROUGH THE AXIS OF GREATEST SURFACE BASED
   INSTABILITY WITH 500-1000 J/KG MLCAPE AND MAY REMAIN CAPABLE OF
   PRODUCING ISOLATED LARGE HAIL AND STRONG WIND GUSTS NEXT COUPLE
   HOURS.
   
   OTHER MORE WIDELY SCATTERED DISCRETE STORMS HAVE DEVELOPED FARTHER
   EAST IN WARM SECTOR ACROSS W CNTRL KY WHERE DIABATIC HEATING HAS
   BEEN SUFFICIENT TO DESTABILIZE THE BOUNDARY LAYER. THIS ACTIVITY IS
   DEVELOPING WITHIN AN ENVIRONMENT WITH WEAK MID LEVEL LAPSE RATES BUT
   WITHIN BAND OF STRONG BULK SHEAR ATTENDING MID LEVEL JET ROTATING
   THROUGH BASE OF UPPER TROUGH. SOME OF THESE STORMS APPEAR TO BE
   INTERACTING WITH A COUPLE OF E-W ORIENTED SURFACE BOUNDARIES AND VWP
   DATA SHOW VEERING WITHIN THE LOWEST 2 KM. HOWEVER...WEAK FLOW IS
   LIMITING THE SIZE OF LOW LEVEL HODOGRAPHS. MARGINALLY SEVERE
   HAIL...GUSTY WINDS AND AN ISOLATED BRIEF TORNADO WILL BE POSSIBLE
   NEXT HOUR OR TWO WITH THESE STORMS...BUT TREND SHOULD BE FOR
   ACTIVITY TO BEGIN A GRADUAL DECREASE IN INTENSITY WITH THE ONSET OF
   NOCTURNAL COOLING.
   
   ..DIAL.. 09/26/2009
   
   
   ATTN...WFO...LMK...OHX...PAH...
   
   LAT...LON   36808962 37958751 38648645 38018590 36718633 36648874
               36808962