MESOSCALE DISCUSSION 1236
   NWS STORM PREDICTION CENTER NORMAN OK
   1227 PM CDT THU JUN 21 2007
   
   AREAS AFFECTED...PARTS OF SRN WI/NRN IL TO THE EAST OF WW 434
   
   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 
   
   VALID 211727Z - 211830Z
   
   ISOLATED SEVERE TSTMS WILL BE POSSIBLE ACROSS PART OF SRN WI AND NRN
   IL TO THE EAST OF WW 434.  IF CONVECTION INCREASES IN INTENSITY
   AND/OR THERE IS INDICATION FOR A GREATER COVERAGE OF SEVERE
   TSTMS...THEN A WW MAY BE NEEDED.
   
   17Z SURFACE ANALYSIS SHOWED A BOUNDARY OVER NRN IL AND EXTENDING
   NWWD THROUGH SWRN WI INTO SRN MN AS A WARM FRONT.  REGIONAL RADARS
   INDICATED A FEW TSTMS INCREASING IN INTENSITY ALONG THE BOUNDARY IN
   SWRN WI...WITH ACTIVITY THEN MOVING ESEWD INTO SRN WI TO THE E AND N
   OF THE SURFACE BOUNDARY.  WEAK WAA IS EXPECTED TO MAINTAIN THESE
   TSTMS THROUGH THE AFTERNOON...WITH MARGINAL INSTABILITY AND
   EFFECTIVE BULK SHEAR UP TO 40-45 KT SUPPORTIVE FOR A FEW SEVERE
   TSTMS PRODUCING HAIL AND STRONG WIND GUSTS.  ANY SEVERE THREAT
   SHOULD BE TEMPERED WITH EWD EXTENT GIVEN MORE STABLE MARINE AIR MASS
   ADVECTING WWD AS INDICATED BY LAKE BREEZE BOUNDARY WHICH NOW
   EXTENDED FROM DUPAGE COUNTY IL TO DODGE COUNTY WI.
   
   ..PETERS.. 06/21/2007
   
   
   ATTN...WFO...LOT...MKX...DVN...ARX...
   
   43699034 43458859 42708842 41948817 41728885 41949007
   42419051