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WWUS20 KWNS 181926

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SPC WW 181926

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URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 657

NWS STORM PREDICTION CENTER NORMAN OK

230 PM CDT MON JUL 18 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       CENTRAL AND NORTHEAST WISCONSIN

       LAKE MICHIGAN



EFFECTIVE THIS MONDAY AFTERNOON AND EVENING FROM 230 PM UNTIL 900

PM 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 35 MILES NORTHEAST

OF GREEN BAY WISCONSIN TO 85 MILES WEST OF MOSINEE WISCONSIN.

FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU7).



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...SCATTERED THUNDERSTORMS HAVE DEVELOPED ALONG A DIFFUSE

COLD FRONT ACROSS NRN WI...AND THIS CONVECTION WILL INTENSIFY WHILE

SPREADING SEWD TOWARD CENTRAL/NE WI THROUGH THE AFTERNOON.  THE

STORMS WILL BE FED BY A CORRIDOR OF STRONG INSTABILITY...WHILE

EFFECTIVE BULK SHEAR OF 35-40 KT WILL SUPPORT SUPERCELLS CAPABLE OF

PRODUCING LARGE HAIL AND DAMAGING WINDS.



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 32030.





...THOMPSON

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