

603 

WWUS20 KWNS 202238

SEL0

SPC WW 202238

MIZ000-LMZ000-210400-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 630

NWS STORM PREDICTION CENTER NORMAN OK

540 PM CDT FRI AUG 20 2010



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       LARGE PART OF CENTRAL AND NORTHERN LOWER MICHIGAN

       LAKE MICHIGAN



EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 540 PM UNTIL

1100 PM CDT.



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 EAST AND WEST OF A LINE FROM 35 MILES NORTH

NORTHEAST OF TRAVERSE CITY MICHIGAN TO 30 MILES SOUTHWEST OF

GRAND RAPIDS MICHIGAN.  FOR A COMPLETE DEPICTION OF THE WATCH SEE

THE ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU0).



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 627...WW 628...WW 629...



DISCUSSION...LINE OF SEVERE THUNDERSTORMS MOVING EWD ACROSS LM WILL

MAINTAIN A DAMAGING WIND POTENTIAL FOR SEVERAL HOURS AS AIR MASS

ACROSS THE WATCH AREA IS MDTLY UNSTABLE WITH 30-40KT OF SHEAR.



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 550. MEAN STORM

MOTION VECTOR 26030.





...HALES

