SPC MESOSCALE DISCUSSION 1168 FOR EXTREME SERN MN...SWRN WI AND
   NCNTRL THROUGH NERN IA
   CONCERNING...SEVERE THUNDERSTORM WATCH 439...
   
   VALID 191221Z - 191400Z
   
   THREAT FOR PRIMARILY LARGE HAIL WILL CONTINUE NEXT FEW HOURS FROM
   NERN IA INTO EXTREME SERN MN AND SWRN WI. THREAT APPEARS A LITTLE
   HIGHER OVER IA PORTION OF WW. VERY HEAVY RAIN WITH RATES BETWEEN 1
   AND 1.5 INCHES PER HOUR IS ALSO LIKELY TO CONTINUE OVER NERN IA.
   
   BAND OF ELEVATED STORMS EXTEND FROM WRN WI SWD THROUGH EXTREME SERN
   MN INTO NERN IA. THIS BAND HAS BEEN SHIFTING SLOWLY EWD. HOWEVER...
   PROPAGATION COMPONENT ASSOCIATED WITH STRONG SSWLY LOW LEVEL JET IS
   PROMOTING WWD BACKBUILDING INTO N CNTRL IA ALONG CONVECTIVE OUTFLOW
   BOUNDARY. THIS SUGGESTS HEAVY RAIN THREAT WILL PERSIST OVER NERN IA
   NEXT FEW HOURS AS STORMS BACKBUILD AND SUBSEQUENTLY TRAIN EWD. THE
   STRONGEST ACTIVITY IS EXPECTED TO PERSIST OVER NERN IA WHERE STORMS
   HAVE UNOBSTRUCTED INFLOW FROM LOW LEVEL JET THAT HAS VEERED TO
   SWLY.
   
   ..DIAL.. 06/19/02