

951 

WWUS20 KWNS 251445

SEL1

SPC WW 251445

MIZ000-LHZ000-252000-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 181

NWS STORM PREDICTION CENTER NORMAN OK

1045 AM EDT SAT APR 25 2009



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       MUCH OF LOWER MICHIGAN

       LAKE HURON



EFFECTIVE THIS SATURDAY MORNING AND AFTERNOON FROM 1045 AM UNTIL

400 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 80

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

OF GRAND RAPIDS MICHIGAN TO 40 MILES EAST OF BAD AXE 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...LINES OF THUNDERSTORMS INCREASING AND MOVING RAPIDLY

EWD ACROSS LWR MI WHERE AIRMASS HAS DESTABILIZED UNDER STRONG

MORNING HEATING.  WITH 40-50KT OF SHEAR DAMAGING WINDS WILL BE THE

PRIMARY THREAT AS STRONG WIND MAX PASSES JUST TO THE NORTH OF AREA.



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 450. MEAN STORM

MOTION VECTOR 25035.





...HALES

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