MESOSCALE DISCUSSION 1661
   NWS STORM PREDICTION CENTER NORMAN OK
   0352 PM CDT FRI JUL 24 2009
   
   AREAS AFFECTED...ERN IA/SWRN WI
   
   CONCERNING...TORNADO WATCH 617...
   
   VALID 242052Z - 242215Z
   
   THE SEVERE WEATHER THREAT FOR TORNADO WATCH 617 CONTINUES.
   
   LOCAL SEVERE POTENTIAL CONTINUES ACROSS WW 617.
   
   LATEST RADAR IMAGERY INDICATES THAT THE EARLIER/INTENSE SUPERCELL
   OVER ERN IA HAS DISSIPATED...BUT ADDITIONAL STRONG/LOCALLY-SEVERE
   STORMS CONTINUE OVER FAR SERN MN/NERN IA/SWRN WI...AHEAD OF THE
   SURFACE COLD FRONT WHERE SOME DESTABILIZATION HAS OCCURRED IN THE
   WAKE OF EARLIER STORMS.  WITH A CONVECTIVE BOUNDARY OVER ERN IA AND
   LOCALLY-BACKED LOW-LEVEL FLOW...A LIMITED TORNADO THREAT MAY LINGER
   OVER PARTS OF NERN IA AND VICINITY.  HOWEVER...GREATER THREAT IN THE
   SHORT TERM APPEARS TO BE HAIL AND LOCALLY-DAMAGING WINDS.  
   
   ATTM...PROSPECTS FOR ADDITIONAL/LATER STORM DEVELOPMENT -- AND THUS
   AN EXPANSION IN SEVERE POTENTIAL -- REMAIN UNCERTAIN.  DEEP-LAYER
   FLOW REMAINS SUPPORTIVE OF SEVERE STORMS...AND DEGREE OF INSTABILITY
   ACROSS MUCH OF IA AND SRN MN AHEAD OF THE FRONT WOULD SUPPORT STORMS
   SHOULD INITIATION OCCUR.  ATTM HOWEVER...ANY NEW STORM DEVELOPMENT
   REMAINS FAR FROM CERTAIN -- IN BOTH TIMING AND LOCATION -- WITH A
   GENERAL LACK OF LARGE-SCALE SUPPORT EVIDENT IN WV IMAGERY AND ONLY
   LIMITED CU DEVELOPMENT ALONG THE FRONT.  WITH BOTH WW 616 AND 617
   SET TO EXPIRE AT 24/22Z...PORTIONS OF SERN MN/WRN WI/IA/NRN IL MAY
   REQUIRE NEW WW ISSUANCE TO COVER THE EVOLVING -- BUT UNCERTAIN --
   SEVERE POTENTIAL...WHICH WOULD APPEAR ATTM TO BE GREATEST ACROSS ERN
   IA/NWRN IL.
   
   ..GOSS.. 07/24/2009
   
   
   ATTN...WFO...LOT...ILX...MKX...DVN...ARX...DMX...
   
   LAT...LON   41139184 42319217 43699181 43499011 41448825 40618966
               40769138 41139184