MESOSCALE DISCUSSION 1241
   NWS STORM PREDICTION CENTER NORMAN OK
   0537 PM CDT FRI JUN 19 2009
   
   AREAS AFFECTED...PARTS OF ERN IA / MUCH OF CNTRL-NRN IL / NWRN AND
   W-CNTRL IND
   
   CONCERNING...SEVERE THUNDERSTORM WATCH 480...
   
   VALID 192237Z - 192330Z
   
   THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 480
   CONTINUES.
   
   ENHANCED DMGG WIND POTENTIAL LIKELY TO EVOLVE AND SPREAD EWD ACROSS
   ERN IL / WRN IND THIS EVENING.  
   
   RECENT TRENDS IN RADAR MOSAIC ARE SHOWING A LEWP DEVELOPING ACROSS
   ERN IA EXTENDING INTO NWRN IL WITH A BROKEN SQUALL LINE FROM 35 MI
   NNW ALN TO 40 MI ENE MLI.  KOTM SURFACE OBSERVATION RECORDED SEVERE
   WIND GUSTS AROUND 60 KTS IN THE PAST HOUR.  MESOANALYSIS SHOWS A
   SUB-SYNOPTIC 1000MB SURFACE LOW 15 MI SSE CID WITH AN EFFECTIVE WARM
   FRONT/OUTFLOW BOUNDARY EXTENDING FROM 25 MI W OF RFD ESEWD THROUGH
   THE CHICAGO METRO TO 15 MI SW OF FWA.  SURFACE PRESSURE FALLS OF
   1-1.5 MB/HR HAVE BEEN NOTED ACROSS IL IN ADVANCE OF ERN MCS.  
   
   AREAS E AND S OF MCS AND AFOREMENTIONED BOUNDARIES /I.E. ERN HALF OF
   IL N OF I-70 AND E OF I-35-I-55/ HAVE BECOME MODERATELY-VERY
   UNSTABLE WITHIN A STRONG WLY AND DEEPLY SHEARED ENVIRONMENT.  AS
   SUCH...EXPECTING STORMS/COLD POOL TO CONTINUE TO ORGANIZE WITH BOTH
   MCS/S.  THE LEAD MCS WILL LIKELY POSE THE GREATEST THREAT FOR DMGG
   WINDS AS MS RIVER MCS INGESTS CONVECTIVELY OVERTURNED AIRMASS.  A
   CONCENTRATED SWATH OF SEVERE/DMGG WINDS IS BECOMING MORE
   LIKELY...ESPECIALLY ACROSS E-CNTRL AND NWRN IND.
   
   ..SMITH.. 06/19/2009
   
   
   ATTN...WFO...IWX...IND...LOT...ILX...LSX...DVN...
   
   LAT...LON   39298844 38968988 38999032 39449126 39759171 40029212
               40299190 40699135 41149107 41869099 42149062 42288943
               42238821 41968701 40878626 40068673 39458743 39298844