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000 

WWUS20 KWNS 251823

SEL9

SPC WW 251823

MIZ000-WIZ000-LMZ000-LSZ000-260200-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 749

NWS STORM PREDICTION CENTER NORMAN OK

120 PM CDT FRI JUL 25 2008



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       UPPER MICHIGAN

       NORTHERN WISCONSIN

       LAKE MICHIGAN

       LAKE SUPERIOR



EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 120 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 140

STATUTE MILES EAST AND WEST OF A LINE FROM 40 MILES NORTHWEST OF

MARQUETTE MICHIGAN TO 55 MILES SOUTHWEST OF RHINELANDER

WISCONSIN.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU9).



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...THUNDERSTORMS ARE GRADUALLY INCREASING IN COVERAGE FROM

NWRN WI INTO THE WRN UPPER PENINSULA OF MI...AHEAD OF A COLD FRONT

AND STRONG UPPER TROUGH MOVING EWD TOWARD THE UPPER GREAT LAKES.

EARLIER CLOUD COVER HAS THINNED OVER UPPER MI...AND LATEST VISIBLE

IMAGERY INDICATES CLOUDS ARE BEGINNING TO DIMINISH OVER NERN WI IN

ADVANCE OF A CLUSTER OF STORMS OVER NORTH CENTRAL WI.  THIS WILL

PROMOTE REGIONS OF ENHANCED HEATING AND DESTABILIZATION TO

OCCUR...WITH MLCAPE OF 1000-1500 J/KG EXPECTED.  VAD WIND PROFILES

SHOW STRONGER WESTERLY MID LEVEL FLOW OVER THE AREA CONTRIBUTING

SUFFICIENT DEEP LAYER SHEAR /30-40 KT IN THE LOWEST 6 KM AGL/ TO

ENHANCE SEVERE THUNDERSTORM POTENTIAL.  DAMAGING WIND GUSTS AND

OCCASIONAL HAIL ARE LIKELY WITH STRONGER STORMS.



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 27035.





...WEISS

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