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WWUS20 KWNS 080836

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SPC WW 080836

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URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 491

NWS STORM PREDICTION CENTER NORMAN OK

435 AM EDT SUN JUL 8 2007



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       U.P.  AND FAR NORTHERN TIP OF LOWER MICHIGAN

       LAKE HURON

       LAKE MICHIGAN

       LAKE SUPERIOR



EFFECTIVE THIS SUNDAY MORNING FROM 435 AM UNTIL 1100 AM EDT.



HAIL TO 3 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 40 MILES SOUTH OF

HOUGHTON MICHIGAN TO 35 MILES NORTHEAST OF PELLSTON MICHIGAN.

FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU1).



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...INTENSE STORMS IN THE FORM OF ELEVATED SUPERCELLS

SHOULD PERSIST ESEWD ACROSS WW THROUGH THE EARLY MORNING HOURS.

EXTREMELY UNSTABLE AIR MASS AND VERY STEEP LAPSE RATES WILL ENHANCE

THE THREAT OF LARGE HAIL...SOME OF WHICH COULD BE QUITE LARGE.

ACTIVITY MAY EVOLVE INTO A LINEAR MCS WITH INCREASING POTENTIAL FOR

DAMAGING WINDS IF ORGANIZED COLD POOL BECOMES ESTABLISHED.



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

TO 3 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 550. MEAN STORM

MOTION VECTOR 29035.





...EVANS

