MESOSCALE DISCUSSION 1580
   NWS STORM PREDICTION CENTER NORMAN OK
   0120 PM CDT WED AUG 24 2016

   AREAS AFFECTED...PARTS OF CNTRL ILLINOIS THROUGH CNTRL/SRN IND

   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

   VALID 241820Z - 241945Z

   PROBABILITY OF WATCH ISSUANCE...40 PERCENT

   SUMMARY...IT IS NOT CERTAIN THAT A SEVERE WEATHER WATCH WILL BE
   NEEDED THIS AFTERNOON.  HOWEVER...CONVECTIVE TRENDS WILL CONTINUE TO
   BE MONITORED FOR THE POSSIBILITY OF INCREASING SEVERE WEATHER
   POTENTIAL WHICH COULD EVENTUALLY REQUIRE ONE.

   DISCUSSION...RECENT THUNDERSTORM INTENSIFICATION TO THE EAST
   SOUTHEAST OF DANVILLE IL IS OCCURRING ALONG A NORTHWEST-SOUTHEAST
   ORIENTED ZONE OF STRENGTHENING DIFFERENTIAL SURFACE HEATING.  THIS
   IS ALSO JUST AHEAD OF A REMNANT CONVECTIVELY GENERATED OR ENHANCED
   LOW/MID-LEVEL CYCLONIC VORTICITY CENTER...WHICH ALSO APPEARS TO BE
   AIDING INITIATION OF NEW CONVECTIVE DEVELOPMENT EITHER SIDE OF THE
   SURFACE BOUNDARY ACROSS NORTHERN/CENTRAL ILLINOIS.  

   ALONG AND SOUTH OF THE SURFACE BOUNDARY...THE BOUNDARY LAYER IS
   BECOMING MODERATELY UNSTABLE /AS CHARACTERIZED BY CAPE IN EXCESS OF
   2000 J PER KG/ WITH CONTINUING INSOLATION.  THIS IS OCCURRING IN THE
   PRESENCE OF A BELT OF AT LEAST MODESTLY SHEARED 30+ KT WESTERLY DEEP
   LAYER MEAN FLOW.  ALTHOUGH VARIOUS HIGH-RESOLUTION CONVECTION
   ALLOWING MODEL OUTPUT REMAIN UNCLEAR CONCERNING POTENTIAL FURTHER
   CONVECTIVE DEVELOPMENT THIS AFTERNOON...THIS ENVIRONMENT APPEARS
   CONDUCIVE TO THE EVOLUTION OF AN UPSCALE GROWING THUNDERSTORM
   CLUSTER AND STRENGTHENING SURFACE COLD POOL THAT COULD EVENTUALLY BE
   ACCOMPANIED BY THE RISK FOR STRONG SURFACE GUSTS.

   ..KERR/WEISS.. 08/24/2016


   ATTN...WFO...ILN...LMK...IWX...IND...LOT...ILX...

   LAT...LON   41068851 40938730 40528574 39988497 38898520 38838671
               38998789 39608925 40528944 41068851