MESOSCALE DISCUSSION 0907
   NWS STORM PREDICTION CENTER NORMAN OK
   0131 PM CDT MON JUN 01 2009
   
   AREAS AFFECTED...PARTS OF FAR ERN IA / NRN IL / NWRN AND N-CNTRL IND
   
   CONCERNING...SEVERE POTENTIAL...WATCH LIKELY 
   
   VALID 011831Z - 011930Z
   
   THE SEVERE THREAT WILL GRADUALLY INCREASE THIS AFTERNOON ACROSS
   PORTIONS OF FAR ERN IA/NRN IL EXTENDING EWD INTO NWRN AND N-CNTRL
   IND TOWARDS LATE AFTERNOON/EARLY EVENING.  THE PRIMARY THREAT WITH
   THE ACTIVITY WILL BE LARGE HAIL/DMGG WINDS.
   
   VISIBLE IMAGERY SHOWS A MID-LEVEL VORTICITY MAXIMUM MOVING ESEWD
   OVER CNTRL IA AS OF 1830Z.  RECENT SURFACE ANALYSIS SHOWS A SAGGING
   SEWD MOVING COLD FRONT OVER PARTS OF SERN WI DRAPED WSWWD INTO
   E-CNTRL IA.  OUTFLOW BOUNDARY ORIGINATING FROM LAST NIGHTS MCS NOW
   OVER SERN OH/WRN WV HAS BEEN REINFORCED AS STRONG INSOLATION TO THE
   S OF THE BOUNDARY IS CONTRIBUTING TO A SUBSTANTIAL DIFFERENTIAL
   HEATING ZONE/MODEST LOW LEVEL CONVERGENCE TRAILING NWWD INTO NWRN
   IND/NRN IL.
   
   AS TEMPS CONTINUE TO WARM INTO THE 80S F AMIDST A HIGHER QUALITY
   MOIST AIRMASS /PRECIPITABLE WATER 1.4 INCH/ RESIDING OVER NRN
   IL/NWRN IND...AN AREA OF MODERATE POTENTIAL INSTABILITY
   /CHARACTERIZED BY MLCAPE 2000-3000 J/KG/ HAS DEVELOPED ALONG AND S
   OF THE BOUNDARY.  SOMEWHAT FOCUSED AREA OF ASCENT ALONG INTERSECTION
   OF COLD FRONT/DIFFERENTIAL HEATING BOUNDARY AHEAD OF APPROACHING
   VORTICITY MAXIMUM SHOULD PROVE ENOUGH TO WEAKEN THE CAP WITH
   ADDITIONAL TSTM DEVELOPMENT.  ALTHOUGH SURFACE WINDS HAVE VEERED TO
   WLY...A WLY 50+ KT MID-LEVEL SPEED MAX /SAMPLED BY WLC/LOT VWP DATA/
   SHOULD AID IN ORGANIZING STORMS INTO CLUSTERS/SMALL BOWING SEGMENTS
   WITH TIME.  AS STORMS MATURE AND ORGANIZE...THEY WILL LIKELY POSE A
   LARGE HAIL/DMGG WIND THREAT EVOLVING INTO MORE OF A WIND THREAT AS
   STORMS MOVE GENERALLY ESEWD ALONG INSTABILITY GRADIENT.
   
   ..SMITH.. 06/01/2009
   
   
   ATTN...WFO...IWX...IND...LOT...ILX...DVN...
   
   LAT...LON   40668840 41088970 41319079 41499111 41649110 41849094
               41919079 42078995 42118957 42018851 41838704 41678669
               41408639 40978631 40618650 40328681 40308754 40668840