MESOSCALE DISCUSSION 2040
   NWS STORM PREDICTION CENTER NORMAN OK
   1104 PM CDT SUN SEP 27 2009
   
   AREAS AFFECTED...E-CNTRL THROUGH NE IL INTO CNTRL AND SRN IN THROUGH
   WRN OH
   
   CONCERNING...TORNADO WATCH 745...
   
   VALID 280404Z - 280530Z
   
   THE SEVERE WEATHER THREAT FOR TORNADO WATCH 745 CONTINUES.
   
   THREAT FOR ISOLATED DAMAGING WIND...MARGINALLY SEVERE HAIL AND
   PERHAPS AN ISOLATED TORNADO OR TWO WILL PERSIST NEXT HOUR OR
   TWO...MAINLY FROM E CNTRL AND NERN IL THROUGH NW IND. SWD
   DEVELOPMENT INTO SRN PARTS OF WW INCLUDING S CNTRL IL IS BECOMING
   INCREASINGLY UNLIKELY. HOWEVER...STORMS ARE EXPECTED TO INCREASE
   FARTHER EAST INTO SRN IND AND WRN OH WHERE A NEW WW MAY BE NEEDED
   SOON.
   
   BROKEN LINE OF STORMS EXTENDS FROM SWRN LOWER MI...NWRN IND INTO
   EXTREME E CNTRL IL MOVING EAST AT AROUND 35 KT. THE STORMS ARE
   DEVELOPING WITHIN AXIS OF MARGINAL INSTABILITY AND ASCENT WITHIN
   EXIT REGION OF ESEWD MOVING UPPER JET. STORMS ARE APPROACHING THE
   ERN EDGE OF WW AND QUESTION REMAINS HOW FAR SW ADDITIONAL
   DEVELOPMENT WILL OCCUR IF AT ALL. SURFACE DATA INDICATE STRONGEST
   PRESSURE FALLS EXTEND FROM EXTREME E-CNTRL PA THROUGH NW IND INTO
   SRN LOWER MI. CURRENT INDICATIONS ARE THAT THE ZONE OF DEEPER
   FORCING IS BEGINNING TO SHIFT EAST OF THE SWRN EXTENSION OF THE COLD
   FRONT SUGGESTING SWD DEVELOPMENT INTO REMAINING PARTS OF WW 745 IS
   BECOMING INCREASINGLY UNLIKELY. FUTURE DEVELOPMENT WILL LIKELY
   REMAIN WITHIN ZONE OF WARM ADVECTION AND LIFT ACROSS CNTRL/SRN IND
   WHERE STORMS ARE CURRENTLY INCREASING.
   
   ..DIAL.. 09/28/2009
   
   
   ATTN...WFO...ILN...IWX...IND...LOT...ILX...
   
   LAT...LON   40618734 40228464 39298523 39558816 39268906 39838943
               41478756 40618734