MESOSCALE DISCUSSION 1198
   NWS STORM PREDICTION CENTER NORMAN OK
   0320 AM CDT THU JUN 18 2009
   
   AREAS AFFECTED...MO...IA...IL
   
   CONCERNING...SEVERE THUNDERSTORM WATCH 455...
   
   VALID 180820Z - 180945Z
   
   THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 455
   CONTINUES.
   
   A PAIR OF INTENSE CONVECTIVE COMPLEXES WERE SPREADING ACROSS SERN IA
   THIS MORNING WITH DAMAGING WINDS AND HAIL LIKELY. THIS ACTIVITY WAS
   OCCURRING ON THE NERN PERIPHERY OF PLAINS CAPPING INVERSION AND
   ALONG QUASI-STATIONARY WARM FRONT FROM SRN IA TO THE LOWER OH RIVER
   VALLEY. LIFT ACROSS THIS BOUNDARY...AND BAND OF STRONGER MID-LEVEL
   FLOW WILL CONTRIBUTE TO KEEPING THIS CONVECTION WELL-ORGANIZED OVER
   THE NEXT SEVERAL HOURS. MAGNITUDE OF INSTABILITY ACROSS THE REGION
   WILL ALSO RESULT IN INTENSE UPDRAFTS WITH THESE COMPLEXES AND THE
   CONTINUED THREAT FOR DAMAGING WINDS.
   
   LATEST LINEAR EXTRAPOLATION INDICATES THAT THE TRAILING CLUSTER OF
   STORMS...MOVING AT NEARLY 50KT...WILL CATCH-UP AND LIKELY MERGE WITH
   THE SLOWER MOVING AND LARGER CLUSTER NOW CROSSING THE MS RIVER. THIS
   MERGER WILL LIKELY OCCUR ACROSS NRN/CNTRL IL IN A COUPLE OF HOURS. A
   WATCH WILL LIKELY BE NEEDED ACROSS THESE AREA...AND PERHAPS SWD
   ACROSS CNTRL IL IN ANOTHER HOUR OR SO.
   
   ..CARBIN.. 06/18/2009
   
   
   ATTN...WFO...ILX...LSX...DVN...DMX...EAX...
   
   LAT...LON   39589041 40589240 41339355 41869219 41598971 39698812
               38888927 39589041