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000 

WWUS20 KWNS 112320

SEL6

SPC WW 112320

MNZ000-WIZ000-LSZ000-120600-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 586

NWS STORM PREDICTION CENTER NORMAN OK

620 PM CDT SAT AUG 11 2007



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       EASTERN AND SOUTHERN MINNESOTA

       WESTERN AND NORTHERN WISCONSIN

       LAKE SUPERIOR



EFFECTIVE THIS SATURDAY NIGHT AND SUNDAY MORNING FROM 620 PM

UNTIL 100 AM CDT.



HAIL TO 2 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 95

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 65 MILES SOUTH

SOUTHEAST OF KENNEDY WISCONSIN TO 45 MILES WEST NORTHWEST OF

MANKATO MINNESOTA.  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.



DISCUSSION...ISOLATED THUNDERSTORMS HAVE BEGUN TO FORM IN EXTREMELY

UNSTABLE AIR MASS OVER CENTRAL MN.  THESE STORMS ARE EXPECTED TO

BECOME SEVERE AND SPREAD EAST-SOUTHEASTWARD INTO WESTERN WI DURING

THE EVENING HOURS.  EFFECTIVE SHEAR VALUES ARE FAVORABLE FOR

SUPERCELL STORM STRUCTURES CAPABLE OF DAMAGING WINDS AND LARGE HAIL.



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

TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 600. MEAN STORM

MOTION VECTOR 28030.





...HART

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