MESOSCALE DISCUSSION 0420
   NWS STORM PREDICTION CENTER NORMAN OK
   0908 AM CDT TUE APR 03 2007
   
   AREAS AFFECTED...CENTRAL/ERN IL INTO WRN IND
   
   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 
   
   VALID 031408Z - 031515Z
   
   TSTMS SHOULD CONTINUE TO DEVELOP ALONG THE SRN FLANK OF AN OUTFLOW
   BOUNDARY...WHICH IS NOW MOVING EWD THROUGH E CENTRAL IL...WITH
   ACTIVITY THEN AFFECTING WRN IND.  LOCALIZED THREAT AT THIS TIME
   SUGGESTS WW WOULD NOT BE REQUIRED IN THE SHORT TERM.  HOWEVER...
   AREA WILL CONTINUE TO BE MONITORED FOR SURFACE BASED DEVELOPMENT AND
   GREATER DOWNSTREAM DESTABILIZATION.
   
   MORNING SURFACE ANALYSES SHOWED A CONVECTIVE OUTFLOW BOUNDARY MOVING
   EWD AND AT 14Z EXTENDED FROM FAR NWRN IND SWWD THROUGH ERN IL TO
   NORTH OF STL.  SURFACE PRESSURE RISES ARE GREATEST ACROSS THE NRN
   HALF OF IL.  THIS WOULD SUGGEST THAT THIS PORTION OF THE OUTFLOW
   WILL LIKELY REMAIN MOST PROGRESSIVE AND CONVECTIVELY ACTIVE VERSUS
   SRN EXTENT NEAR STL WHERE NEW STORMS SHOULD OCCUR MORE SO IN POST-
   OUTFLOW ENVIRONMENT.
   
   ALTHOUGH AIR MASS FARTHER EWD INTO IND IS MORE STABLE...TSTMS
   CURRENTLY DEVELOPING OVER ERN IL /JUST W OF OUTFLOW BOUNDARY/ ARE
   LIKELY BEING FED BY GREATER INSTABILITY LOCATED SWWD OVER MO PER 50
   KT SWLY LLJ AT SGF.  EFFECTIVE SHEAR AND ELEVATED INSTABILITY SHOULD
   REMAIN SUFFICIENT FOR ISOLATED THREAT OF LARGE HAIL.
   
   ..PETERS.. 04/03/2007
   
   
   ATTN...WFO...IWX...IND...PAH...LOT...ILX...LSX...
   
   40618842 41358782 41258730 40328696 39208752 38318861
   38008975 38139038 39109075 39848937