MESOSCALE DISCUSSION 1043
   NWS STORM PREDICTION CENTER NORMAN OK
   0626 PM CDT TUE MAY 31 2011
   
   AREAS AFFECTED...PORTIONS ERN IL...LOWER MI...WRN/NRN INDIANA...ERN
   UPPER MI...EXTREME NWRN OH.
   
   CONCERNING...SEVERE THUNDERSTORM WATCH 407...408...
   
   VALID 312326Z - 010130Z
   
   THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH
   407...408...CONTINUES.
   
   SFC MAP SHOWED DIFFUSE COLD FRONTAL ZONE -- WITH ONLY GRADUAL
   SWLY-WSWLY WIND SHIFT AND VERY WEAK CONVERGENCE INDICATED -- FROM
   E-CENTRAL UPPER MI SWWD ACROSS S-CENTRAL WI TO NEAR UIN.  PRIMARY
   CONVECTIVE POTENTIAL WILL REMAIN AHEAD OF FRONT ALONG
   SUBTLE/LOCALIZED BOUNDARIES RELATED TO REMNANT AREAS OF DIFFERENTIAL
   HEATING...AND TO POCKETS OF ENHANCED BOUNDARY-LAYER MOISTURE. 
   ISODROSOTHERMAL ANALYSIS SHOWED HIGHLY PATCHY/FRAGMENTED MOISTURE
   FIELD...WITH DEW POINTS NEAR 70 OVER SERN...E-CENTRAL AND SWRN LOWER
   MI...WITH LOWER 60S OVER PORTIONS SRN IL AND WRN LOWER MI.
   
   AS OF 23Z...TSTMS HAVE DEVELOPED AND GROWN RAPIDLY UPSCALE IN TWO
   PRIMARY CLUSTERS AHEAD OF SFC COLD FRONT--NRN LOWER MI AND FROM
   JXN-AMN-OSC.  THIS ACTIVITY WILL MOVE NEWD TOWARD LH IN ENVIRONMENT
   OF WEAK MLCINH...1500-2500 J/KG MLCAPE AND 40-50 KT EFFECTIVE SHEAR
   PER MODIFIED FCST SOUNDINGS.  ADDITIONAL DEVELOPMENT FARTHER W
   TOWARD LM IS OCCURRING ATTM...HOWEVER WW MAY BE CLEARED BEHIND COLD
   FRONT.  FARTHER S ACROSS IL/INDIANA...TSTM FORMATION BECOMES MORE
   ISOLATED/CONDITIONAL...GIVEN INCREASING DISTANCE FROM APPRECIABLE
   HEIGHT FALLS AND DCVA THAT PRECEDE MID-UPPER SHORTWAVE TROUGH.  WITH
   LOSS OF SFC HEATING...AND WEAK FRONTAL LIFT...UNCONDITIONAL SVR
   THREAT SHOULD DIMINISH WITH TIME.  GEN CONVECTIVE TRENDS WITH
   ISOLATED DEVELOPMENT OVER THIS REGION ARE UNFAVORABLE FOR SVR...AND
   PORTIONS WW 408 MAY BE CLEARED BEFORE SCHEDULED 04Z EXPIRATION. 
   MOST OF WW 407 MAY BE CLEAR OF SVR THREAT BY ITS SCHEDULED 02Z
   EXPIRATION...HOWEVER TEMPORAL MAINTENANCE OF SOME ERN LOWER MI AREAS
   MAY BE REQUIRED AS CONVECTIVE TRENDS WARRANT.
   
   ..EDWARDS.. 05/31/2011
   
   
   ATTN...WFO...CLE...DTX...APX...IWX...GRR...IND...LOT...ILX...
   
   LAT...LON   46738478 45898365 45068327 43908260 42888250 42488288
               42378309 42108314 41948318 41758352 39748664 39318786
               39678980 41638774 45168598 46738478