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MIZ000-WIZ000-LMZ000-260700-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 520

NWS STORM PREDICTION CENTER NORMAN OK

640 PM CDT WED JUL 25 2012



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       WESTERN LOWER MICHIGAN

       CENTRAL AND EAST-CENTRAL WISCONSIN

       LAKE MICHIGAN



EFFECTIVE THIS WEDNESDAY NIGHT AND THURSDAY MORNING FROM 640 PM

UNTIL 200 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 55

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 20 MILES NORTH OF

CAMP DOUGLAS WISCONSIN TO 45 MILES EAST OF ROBEN HOOD MICHIGAN.

FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU0).



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 518...WW 519...



DISCUSSION...RECENT TSTM INITIATION HAS OCCURRED JUST W OF GRB INVOF

SURFACE LOW AND COLD FRONT WHERE LOW-LEVEL CONVERGENCE IS BEING

ENHANCED.  STRENGTHENING SWLY LLJ THIS EVENING SHOULD BOOST

CONVERGENCE ALONG THE COLD FRONT...FOSTERING AN INCREASE IN STORMS

OVER E-CNTRL WI WITHIN AN ENVIRONMENT CHARACTERIZED BY MLCAPE OF

2000-3000 J/KG AND 40-50 KT OF DEEP-LAYER SHEAR.  INITIAL STORM MODE

MAY BE SUPERCELLULAR WITH A RISK FOR LARGE HAIL AND POSSIBLY A

TORNADO.  UPSCALE GROWTH INTO A BOW ECHO IS ANTICIPATED LATER ACROSS

LOWER MI WHERE CORRIDORS OF WIND DAMAGE WILL BE POSSIBLE.



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 500. MEAN STORM

MOTION VECTOR 28040.





...MEAD

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