

438 

WWUS20 KWNS 091941

SEL5

SPC WW 091941

MIZ000-LHZ000-LMZ000-100300-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 685

NWS STORM PREDICTION CENTER NORMAN OK

340 PM EDT SUN AUG 9 2009



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       NORTHERN LOWER MICHIGAN

       LAKE HURON

       LAKE MICHIGAN



EFFECTIVE THIS SUNDAY AFTERNOON AND EVENING FROM 340 PM UNTIL

1100 PM EDT.



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 65

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 35 MILES NORTH

NORTHWEST OF MANISTEE MICHIGAN TO 20 MILES EAST OF ALPENA

MICHIGAN.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU5).



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 682...WW 683...WW 684...



DISCUSSION...THUNDERSTORMS WILL CONTINUE TO INCREASE IN COVERAGE

ACROSS NORTHERN LOWER MI THIS AFTERNOON INTO THE EVENING.  VERY

STRONG INSTABILITY COMBINED WITH EFFECTIVE BULK SHEAR AROUND 40 KT

WILL SUPPORT ORGANIZED STORMS CAPABLE OF PRODUCING HAIL AND DAMAGING

WIND GUSTS AS THE PRIMARY SEVERE WEATHER THREATS.



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 26535.





...PETERS/WEISS

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