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000 

WWUS20 KWNS 182039

SEL2

SPC WW 182039

MIZ000-LHZ000-190200-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 532

NWS STORM PREDICTION CENTER NORMAN OK

440 PM EDT WED JUL 18 2007



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       CENTRAL AND SOUTHERN LOWER MICHIGAN

       LAKE HURON



EFFECTIVE THIS WEDNESDAY AFTERNOON AND EVENING FROM 440 PM UNTIL

1000 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 50

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 60 MILES WEST OF

SAGINAW MICHIGAN TO 25 MILES NORTH NORTHEAST OF MOUNT CLEMENS

MICHIGAN.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU2).



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 529...WW 530...WW 531...



DISCUSSION...STRONG STORMS ARE DEVELOPING OVER CENTRAL AND SOUTHERN

LOWER MICHIGAN WITHIN PRIMARY LOW LEVEL CONVERGENCE ZONE ALONG

FRONTAL BOUNDARY.  STRONG HEATING HAS ALLOWED THE AIR MASS TO

DESTABILIZE SUBSTANTIALLY WITH MLCAPE TO 1500 J/KG.  40 KT NWLY MID

LEVEL WINDS ARE RESULTING IN SUFFICIENT DEEP LAYER SHEAR TO SUPPORT

ORGANIZED SEVERE STORMS INCLUDING ISOLATED SUPERCELLS.  LARGE HAIL

AND DAMAGING WINDS ARE POSSIBLE WITH STRONGER CELLS AS THEY MOVE

SEWD 20 KT.



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 30025.





...WEISS

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