WATCHES: Severe Thunderstorm Watch Number 674

WWUS20 KWNS 202242
SEL4
SPC WW 202242
MNZ000-WIZ000-210600-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 674
NWS STORM PREDICTION CENTER NORMAN OK
535 PM CDT THU SEP 20 2007

THE NWS STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

SOUTHEAST MINNESOTA
WESTERN AND CENTRAL WISCONSIN

EFFECTIVE THIS THURSDAY AFTERNOON AND FRIDAY MORNING FROM 535 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 60
STATUTE MILES NORTH AND SOUTH OF A LINE FROM 65 MILES WEST
NORTHWEST OF EAU CLAIRE WISCONSIN TO 65 MILES EAST OF EAU CLAIRE
WISCONSIN. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU4).

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 673...

DISCUSSION...SLIGHTLY ELEVATED MCS WITH EMBEDDED SUPERCELLS NOW IN
THE TWIN CITIES AREA EXPECTED TO CONTINUE GENERALLY E INTO WI
THROUGH MID EVENING. ADDITIONAL DEVELOPMENT MAY CONTINUE TO OCCUR
ON SSW FLANK OF SYSTEM...I.E. IN DIRECTIONAL OF 40+ KT LLJ.
RECOVERING AIR MASS ALONG AND N OF WARM FRONT EXTENDING ESE INTO
CNTRL WI SHOULD ALLOW SVR THREAT TO PERSIST DESPITE FACT THAT
CONVECTIVE SYSTEM WILL BECOME FARTHER REMOVED FROM GREATEST ELEVATED
THETA-E INFLOW. WHILE A TORNADO CANNOT BE RULED OUT...MAIN THREATS
SHOULD BE WIND/HAIL GIVEN CURRENT AND EXPECTED STORM MODE...AND LESS
FAVORABLE SFC WARM SECTOR AIR MASS WITH EWD EXTENT.
FARTHER N...OTHER MORE ELEVATED STORMS EXPECTED TO CONTINUE E ACROSS
NW WI. THESE SHOULD WEAKEN AS THEY BECOME FURTHER ELEVATED AND
INCREASINGLY REMOVED FROM ELEVATED MOIST INFLOW.

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 550. MEAN STORM
MOTION VECTOR 27035.

..CORFIDI

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