MESOSCALE DISCUSSION 1583
   NWS STORM PREDICTION CENTER NORMAN OK
   0215 PM CDT FRI JUL 09 2004
   
   AREAS AFFECTED...FAR NERN IL AND NRN IND
   
   CONCERNING...SEVERE THUNDERSTORM POTENTIAL 
   
   VALID 091915Z - 092115Z
   
   ISOLATED DAMAGING WINDS/LARGE HAIL WILL BE POSSIBLE WITH CONVECTION
   INTENSIFYING ALONG GUST FRONT OVER NERN IL AS IT MOVES INTO NWRN
   IND. OVERALL THREAT APPEARS TO BE MARGINAL AND THUS A WW IS NOT
   ANTICIPATED AT THIS TIME.
   
   LATEST VWP DATA FROM CHICAGO AND IR IMAGERY INDICATES THAT A MID
   LEVEL SPEED MAX EXISTS OVER NRN IL TO THE SOUTH OF AN MCV OVER SRN
   WI. RECENT GOES PW DATA INDICATES LOW LEVEL MOISTURE WAS INCREASING
   NORTH ABOVE SLOWLY ADVANCING WARM FRONT EXTENDING ACROSS NRN IND AND
   FAR NERN IL. SOMEWHAT ELEVATED NATURE OF CONVECTION NORTH OF THIS
   BOUNDARY OVER THE CHI METRO AREA SHOULD LIMIT THE SEVERE WIND
   THREAT. HOWEVER...NEW DEVELOPMENT IS ANTICIPATED TO CONTINUE ALONG
   THE GUST FRONT/WARM FRONTAL BOUNDARY INTERSECTION TO THE SOUTH OF
   CHICAGO INTO FAR NWRN IND OVER THE NEXT FEW HOURS. THIS CONVECTION
   WILL BE ABLE TO TAP MODERATELY UNSTABLE AIRMASS WITH MLCAPES FROM
   2000-2500 J/KG. DESPITE MARGINAL LOW LEVEL INFLOW IN THIS
   AREA...DEGREE OF INSTABILITY...  FOCUSED CONVERGENCE ALONG GUST
   FRONT AND MODEST MID LEVEL FLOW MAY ALLOW FOR ISOLATED DAMAGING
   WIND/HAIL THREAT WITH THE STRONGEST STORMS THROUGH NRN IND.
   
   ..CROSBIE.. 07/09/2004
   
   
   ATTN...WFO...IWX...IND...LOT...
   
   40618770 41268861 41648827 41818745 41678614 41088512
   40348542 40148602