MESOSCALE DISCUSSION 1621
   NWS STORM PREDICTION CENTER NORMAN OK
   0543 AM CDT SAT JUL 05 2003
   
   AREAS AFFECTED...NE IL/S LOWER MI/N IND/NW OH
   
   CONCERNING...SEVERE THUNDERSTORM WATCH 642...
   
   VALID 051043Z - 051215Z
   
   MCS MOVING EWD ACROSS NERN IL WILL CONTINUE TO HAVE A POTENTIAL FOR
   DAMAGING WINDS AND/OR ISOLATED LARGE HAIL AS IT TRACKS EWD ACROSS
   NRN IND/SRN LOWER MI. A NEW WW WILL BE ISSUED E OF WW 642 SHORTLY.
   
   SEVERE CONVECTIVE CLUSTER WITH EMBEDDED BOW ECHOES IS CURRENTLY JUST
   N OF AN AREA OF STRONG INSTABILITY WITH MLCAPE VALUES AROUND 2000
   J/KG. A BAND OF STRONG MID-LEVEL WINDS EXISTS ACROSS NRN IL WITH
   ABOUT 40 KT AT 500 MB. AS THE MCS INTERACTS WITH THE INSTABILITY AND
   SHEAR...A POTENTIAL FOR DAMAGING WINDS AN/OR LARGE HAIL SHOULD
   CONTINUE AS IT TRACKS EWD ACROSS NWRN-NCNTRL IND. HOWEVER...THE MCS
   IS MOVING INTO DECREASING LOW-LEVEL MOISTURE WITH SFC DEWPOINTS IN
   THE MID 60S F. A SHARP INSTABILITY GRADIENT EXISTED E OF THE CLUSTER
   BECAUSE OF A LARGE COLD OUTFLOW REGION GENERATED BY CONVECTION OVER
   IND. THIS WILL LIKELY CAUSE THE LINE TO WEAKEN AGAIN SOME AS IT
   MOVES INTO NERN IND/OH LATER THIS MORNING. HOWEVER...AN ISOLATED
   DAMAGING WIND GUST POTENTIAL SHOULD EXIST FOR THE NEXT FEW HOURS.
   
   ..BROYLES.. 07/05/2003
   
   
   ATTN...WFO...DTX...IWX...GRR...LOT...MKX...
   
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