MESOSCALE DISCUSSION 0469
   NWS STORM PREDICTION CENTER NORMAN OK
   0829 AM CDT TUE APR 19 2011
   
   AREAS AFFECTED...ERN IL...CNTRL AND SRN IND
   
   CONCERNING...SEVERE THUNDERSTORM WATCH 153...
   
   VALID 191329Z - 191430Z
   
   THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 153
   CONTINUES.
   
   AN ISOLATED LARGE HAIL THREAT WILL LIKELY CONTINUE TO MOVE ENEWD
   INTO ERN IL AND SCNTRL IND THIS MORNING. A WW MAY BE NEEDED ACROSS
   PARTS OF THE REGION OVER THE NEXT HOUR.
   
   SEVERAL STRONG TO SEVERE THUNDERSTORMS ARE ONGOING 30 TO 40 STATUTE
   MILES NORTH OF A STATIONARY FRONTAL BOUNDARY EXTENDING FROM CNTRL MO
   EWD INTO SRN IND. MUCAPE VALUES ON THE NORTH SIDE OF THE BOUNDARY
   ARE ESTIMATED FROM AROUND 4000 J/KG NEAR ST LOUIS TO AROUND 2000
   J/KG ACROSS SW IND. THE STORMS ARE ALSO ONGOING ON THE NERN EDGE OF
   A PLUME OF STEEP MID-LEVEL LAPSE RATES IN A STRONGLY SHEARED
   ENVIRONMENT. THE LATEST WSR-88D VWPS IN ERN IL SHOW 65 TO 75 KT OF
   DEEP LAYER SHEAR WHICH WILL CONTINUE TO SUPPORT SUPERCELLS WITH A
   THREAT FOR ISOLATED LARGE HAIL. HOWEVER...INSTABILITY TAPERS OFF EWD
   ACROSS SCNTRL IND SUGGESTING THE THREAT MAY BECOME INCREASINGLY
   ISOLATED THIS MORNING. DUE TO THE ELEVATED NATURE OF THE
   CONVECTION...THE WIND DAMAGE THREAT SHOULD REMAIN MARGINAL.
   
   ..BROYLES.. 04/19/2011
   
   
   ATTN...WFO...ILN...IND...ILX...LSX...
   
   LAT...LON   39328518 38938701 38768887 38948941 39418959 39798939
               40098811 40228712 40298535 39328518