SPC MESOSCALE DISCUSSION 0871 FOR PORTIONS OF ERN IL...MUCH OF IND
   ...WRN OH AND FAR SRN LOWER MI
   CONCERNING...SEVERE THUNDERSTORM POTENTIAL...
   
   VALID 251515Z - 251800Z
   
   THUNDERSTORMS DEVELOPING ALONG PREFRONTAL CONFLUENCE AXIS FROM
   ECENTRAL IL INTO NWRN IND WILL GRADUALLY INTENSIFY OVER THE NEXT
   FEW HOURS AS THEY MORE ENEWD ACROSS IND AND EVENTUALLY INTO WRN OH
   AND FAR SRN LOWER MI. CONTINUED HEATING/DESTABLIZATION WILL NEED TO
   OCCUR IN ORDER FOR AN ORGANIZED SEVERE THREAT TO BECOME REALIZED.
   THUS A WW IS NOT ANTICIPATED UNTIL AFTER 18Z.
   
   15Z SURFACE ANALYSES SHOWED TEMPERATURES IN LOWER 70S ACROSS MUCH
   OF CENTRAL AND SRN IL/IND AND SWRN OH TO THE SOUTH OF THE WARM
   FRONT. COMBINED WITH DEWPOINTS IN THE LOWER TO MID 60S...MUCAPE
   VALUES FROM 1000-1500 J/KG WERE ALREADY PRESENT OVER PORTIONS OF
   THE AREA. INCREASING SWLY MID LEVEL FLOW /AROUND 65 KTS PER RECENT
   ILX VWP/ COMBINED WITH LOW LEVEL SSELY WINDS WAS CONTRIBUTING TO
   BETWEEN 40-45 KTS OF DEEP LAYER SHEAR. RECENT SATELLITE IMAGERY
   SHOWS AMPLE INSOLATION OCCURING OVER MUCH OF SRN AND CENTRAL
   IND...AND THIS SHOULD CONTINUE THROUGH THE EARLY AFTERNOON.
   EXPECTED CONTINUED DESTABILIZATION WILL AID IN A GRADUAL
   STRENGTHENING/DEVELOPMENT OF THE ONGOING/NEW CONVECTION ALONG A
   PREFRONTAL WIND SHIFT LINE ANALYZED FROM NEAR LAF SWWD INTO SERN
   IL. FARTHER WEST...MORE CLOUD COVER WAS OBSERVED ALONG THE COLD
   FRONT...AND THUS CONVECTIVE INITIATION APPEARS MORE UNCERTAIN ALONG
   THIS BOUNDARY. SEVERE THREAT WILL GRADUALLY INCREASE BY EARLY
   AFTERNOON...WITH LARGE HAIL AND DAMAGING WINDS THE PRIMARY THREAT.
   HOWEVER... LOW LEVEL SHEAR WILL REMAIN FAIRLY STRONG WITH 150-300
   M2/S2 OF 0-1 KM SRH ALONG AND NEAR THE NWD MOVING WARM FRONTAL
   BOUNDARY. THUS AN ISOLATED TORNADO MAY ALSO BE POSSIBLE WITH ANY
   SEVERE CONVECTION THAT MAY DEVELOP ALONG THIS BOUNDARY. 
   
   ..CROSBIE.. 05/25/02