MESOSCALE DISCUSSION 1879
   NWS STORM PREDICTION CENTER NORMAN OK
   0133 PM CDT TUE SEP 04 2012
   
   AREAS AFFECTED...CNTRL AND WRN WI...NERN IA...SERN MN
   
   CONCERNING...SEVERE POTENTIAL...WATCH LIKELY 
   
   VALID 041833Z - 042030Z
   
   PROBABILITY OF WATCH ISSUANCE...80 PERCENT
   
   SUMMARY...STORMS ARE EXPECTED TO DEVELOP PRIOR BY 20-21Z WITH VERY
   LARGE HAIL AND DAMAGING WINDS.
   
   DISCUSSION...A COLD FRONT CONTINUES TO PROGRESS EWD TOWARD THE MS
   RIVER AND TRAILING SWWD INTO NWRN IA. STRONG HEATING PERSISTS AND CU
   FIELDS ARE BEGINNING TO FORM. MODIFIED SOUNDINGS SUGGEST
   TEMPERATURES IN THE MOD TO UPPER 80S F WILL ERODE ALL CIN...AND SFC
   CONVERGENCE SHOULD BE ENOUGH TO INITIATE STORMS ALONG THE FRONT.
   LAPSE RATES ALOFT ARE QUITE STEEP...AND WILL SUPPORT RAPID STORM
   DEVELOPMENT. WHILE LOW LEVEL FLOW IS WEAK...MID TO UPPER LEVEL FLOW
   IS SUBSTANTIAL AND SHOULD SUPPORT LONG LIVED SEVERE STORMS INCLUDING
   SUPERCELLS. AS SUCH...VERY LARGE HAIL WILL BE POSSIBLE. DAMAGING
   WINDS WILL ALSO BE A THREAT AS STORMS PRODUCE SIGNIFICANT COLD
   DOWNDRAFTS AND BEGIN TO EXPAND AND FORWARD PROPAGATE LATER TODAY.
   
   ..JEWELL/CORFIDI.. 09/04/2012
   
   
   ATTN...WFO...MQT...GRB...MKX...DVN...DLH...ARX...MPX...DMX...
   
   LAT...LON   44678941 43668944 42698981 42459130 42739231 43699281
               45009283 46029275 46549270 46879217 47049079 46868993
               46358961 44678941