MESOSCALE DISCUSSION 0635
   NWS STORM PREDICTION CENTER NORMAN OK
   0527 PM CDT WED APR 27 2011
   
   AREAS AFFECTED...SERN IL...CNTRL/SRN IND
   
   CONCERNING...TORNADO WATCH 237...239...
   
   VALID 272227Z - 272330Z
   
   THE SEVERE WEATHER THREAT FOR TORNADO WATCH 237...239...CONTINUES.
   
   A NEW TORNADO WATCH WILL LIKELY BECOME NECESSARY N OF WW/S 237/239
   INTO PORTIONS OF CNTRL/SRN IND BY 00Z.
   
   22Z SURFACE ANALYSIS PLACED A 995 MB SURFACE LOW IN EXTREME SRN IL
   AND A QUASI-STATIONARY FRONT EXTENDING NEWD BISECTING IND. ONGOING
   CONVECTIVE CLUSTER/NARROW QLCS COINCIDENT WITH THE SURFACE LOW HAS
   HAD A HISTORY OF EMBEDDED ROTATIONAL SIGNATURES WITHIN A VERY
   STRONGLY SHEARED ENVIRONMENT...0-1 KM SRH AROUND 300 M2/S2 SAMPLED
   BY PAH VWP DATA. AFTERNOON MODEL GUIDANCE IS CONSISTENT IN TRACKING
   THE SURFACE LOW NEWD ALONG THE QUASI-STATIONARY FRONT THROUGH THE
   EVENING HOURS. ALTHOUGH DESTABILIZATION AHEAD OF THE CYCLONE SHOULD
   REMAIN WEAK...ENOUGH OF A BREAK BETWEEN THE PRIMARY
   STRATIFORM/CONVECTIVE REGION IN SERN IND/CNTRL KY MAY BE SUFFICIENT
   TO MAINTAIN TSTM INTENSITY TO THE NE. ISOLATED TORNADOES AND
   DAMAGING WINDS WILL REMAIN THE MAIN THREATS.
   
   ..GRAMS.. 04/27/2011
   
   
   ATTN...WFO...ILN...LMK...IWX...IND...PAH...ILX...
   
   LAT...LON   37298795 37208863 38098889 39518772 40238688 40638558
               40518488 40008477 39488460 39078465 38488554 37788699
               37298795