

000 

WWUS20 KWNS 050015

SEL7

SPC WW 050015

ILZ000-INZ000-MIZ000-LMZ000-050700-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 807

NWS STORM PREDICTION CENTER NORMAN OK

715 PM CDT MON AUG 4 2008



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       NORTHEAST ILLINOIS

       NORTHWEST INDIANA

       EXTREME SOUTHWEST LOWER MICHIGAN

       LAKE MICHIGAN



EFFECTIVE THIS MONDAY NIGHT AND TUESDAY MORNING FROM 715 PM UNTIL

200 AM CDT.



...THIS IS A PARTICULARLY DANGEROUS SITUATION...



EXTREMELY DAMAGING THUNDERSTORM WIND GUSTS TO 90 MPH...LARGE HAIL

TO 2 INCHES IN DIAMETER...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 55 MILES WEST

SOUTHWEST OF MEIGS FIELD ILLINOIS TO 30 MILES SOUTHEAST OF SOUTH

BEND INDIANA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU7).



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 806...



DISCUSSION...DEVELOPING INTENSE BOW ECHO IN NRN IL WILL LIKELY MOVE

THROUGH THE CHICAGO AREA INTO NW INDIANA DURING THE NEXT FEW HOURS.

THE MCS SHOULD MAINTAIN INTENSITY MOVING ALONG A GRADIENT OF EXTREME

INSTABILITY ACROSS NE IL INTO NW INDIANA.  VERY DAMAGING WINDS WILL

BE POSSIBLE IN A NARROW SWATH INCLUDING CHICAGO...ALONG WITH AN

ISOLATED/BRIEF TORNADO AND LARGE HAIL.



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

TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 80

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 600. MEAN STORM

MOTION VECTOR 28050.





...THOMPSON

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