

000 

WWUS20 KWNS 302159

SEL6

SPC WW 302159

IAZ000-MNZ000-WIZ000-310200-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 396

NWS STORM PREDICTION CENTER NORMAN OK

500 PM CDT FRI MAY 30 2008



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       NORTHEAST IOWA

       SOUTHEAST MINNESOTA

       SOUTHWEST WISCONSIN



EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 500 PM UNTIL 900

PM CDT.



HAIL TO 1.5 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70

MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.



THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 45

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 30 MILES WEST

SOUTHWEST OF ROCHESTER MINNESOTA TO 65 MILES SOUTHEAST OF LA

CROSSE WISCONSIN.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU6).



REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE

FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH

AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR

THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS

AND POSSIBLE WARNINGS. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY

DO PRODUCE TORNADOES.



OTHER WATCH INFORMATION...CONTINUE...WW 394...WW 395...



DISCUSSION...SCATTERED THUNDERSTORM CLUSTERS WILL SPREAD ESEWD FROM

MN INTO IA/WI IN ADVANCE OF A MID LEVEL SHORTWAVE TROUGH MOVING

ESEWD OVER THE UPPER MS VALLEY.  MODERATE SURFACE-BASED INSTABILITY

AND EFFECTIVE BULK SHEAR OF 40-50 KT COULD SUPPORT A FEW ORGANIZED

STORMS...INCLUDING SOME WITH SUPERCELL STRUCTURES...CAPABLE OF

PRODUCING LARGE HAIL AND DAMAGING WINDS.  THE SEVERE THREAT SHOULD

DIMINISH A LITTLE AFTER SUNSET AS THE BOUNDARY LAYER STABILIZES.



AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT

TO 1.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM

MOTION VECTOR 24035.





...THOMPSON

