MESOSCALE DISCUSSION 1857
   NWS STORM PREDICTION CENTER NORMAN OK
   0117 PM CDT WED AUG 23 2006
   
   AREAS AFFECTED...SERN MN/PARTS OF CENTRAL-SRN WI/FAR NERN IA/FAR NRN
   IL
   
   CONCERNING...SEVERE THUNDERSTORM POTENTIAL 
   
   VALID 231817Z - 231945Z
   
   WW MAY BE REQUIRED FOR SERN MN/FAR NERN IA INTO PARTS OF CENTRAL/SRN
   WI AND POSSIBLY FAR NRN IL.
   
   EARLY AFTERNOON SURFACE ANALYSIS SHOWED A SURFACE LOW ALONG THE
   CENTRAL PARTS OF THE SD/ND BORDER WITH A WARM FRONT EXTENDING EWD
   INTO CENTRAL MN...THEN SEWD TOWARD LSE TO SERN WI INTO CENTRAL LOWER
   MI.  STRONG SURFACE HEATING ALONG/S OF THIS BOUNDARY WITHIN MOIST
   ENVIRONMENT /SURFACE DEWPOINTS MID-UPPER 60S/ AND STEEP LAPSE RATES
   ARE RESULTING IN A MODERATELY-VERY UNSTABLE AIR MASS /MLCAPE UP TO
   2500 J/KG/.  WAA ALONG NOSE OF 25 KT SWLY LLJ HAS MAINTAINED
   ELEVATED CLUSTER OF STORMS ACROSS CENTRAL WI TO THE N/E OF WARM
   FRONT. ADDITIONAL SURFACE HEATING WILL FURTHER WEAKEN SURFACE BASED
   INHIBITION THIS AFTERNOON...SUGGESTING GREATER LIKELIHOOD FOR STORMS
   TO BECOME SURFACE BASED.  VISIBLE IMAGERY INDICATED NEW CU
   DEVELOPING ALONG THE WARM FRONT IN SERN MN/NERN IA AND ADJACENT
   PARTS OF WI...WHICH MAY BE INDICATIVE OF WEAKENING CINH.  ONCE
   STORMS BECOME SURFACE BASED...INSTABILITY AND 40-50 KT OF EFFECTIVE
   SHEAR WILL SUPPORT SUPERCELLS WITH AN ATTENDANT THREAT FOR LARGE
   HAIL...DAMAGING WINDS AND TORNADO POTENTIAL.
   
   ..PETERS.. 08/23/2006
   
   
   ATTN...WFO...GRB...LOT...MKX...DVN...ARX...MPX...
   
   42579050 43139166 43899255 44429263 44849194 44969101
   44859037 44108921 43238848 42338847 42338988