

415 

WWUS20 KWNS 022223

SEL9

SPC WW 022223

ILZ000-INZ000-MIZ000-OHZ000-WIZ000-LEZ000-LMZ000-030600-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 719

NWS STORM PREDICTION CENTER NORMAN OK

525 PM CDT TUE AUG 2 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       NORTHEAST ILLINOIS

       NORTHERN INDIANA

       CENTRAL AND SOUTHERN LOWER MICHIGAN

       EXTREME NORTHWEST OHIO

       EXTREME SOUTHEAST WISCONSIN

       LAKE ERIE

       LAKE MICHIGAN



EFFECTIVE THIS TUESDAY AFTERNOON AND WEDNESDAY MORNING FROM 525

PM UNTIL 100 AM CDT.



HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 80

MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.



THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 85

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 30 MILES NORTHWEST

OF MARSEILLES ILLINOIS TO 15 MILES SOUTHEAST OF FLINT MICHIGAN.

FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU9).



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...THUNDERSTORMS ARE INTENSIFYING ACROSS SE WI AND

ADJACENT LAKE MI ALONG A DIFFERENTIAL HEATING ZONE/SURFACE

TROUGH...AHEAD OF AN MCV MOVING SEWD OVER WI.  STRONG INSTABILITY IS

PRESENT IN ADVANCE OF THE DEVELOPING CONVECTION...AND DEEP-LAYER

VERTICAL SHEAR IS SUFFICIENT INITIALLY FOR SUPERCELLS...WITH UPSCALE

GROWTH INTO AN MCS EXPECTED THIS EVENING.  WHILE AN ISOLATED TORNADO

CANNOT BE RULED OUT WITH THE INITIALLY DISCRETE STORMS INVOF SE

WI/NE IL...DAMAGING WINDS WILL BECOME THE MAIN THREAT THIS EVENING

AS THE CONVECTION GROWS UPSCALE AND SURGES EWD/SEWD.



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

TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 70

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 650. MEAN STORM

MOTION VECTOR 31035.





...THOMPSON

