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WWUS20 KWNS 131716

SEL5

SPC WW 131716

ILZ000-INZ000-MIZ000-OHZ000-LMZ000-140000-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 775

NWS STORM PREDICTION CENTER NORMAN OK

1215 PM CDT SAT AUG 13 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       NORTHERN AND CENTRAL ILLINOIS

       NORTHERN INDIANA

       SOUTHERN LOWER MICHIGAN

       FAR NORTHWESTERN OHIO

       LAKE MICHIGAN



EFFECTIVE THIS SATURDAY AFTERNOON AND EVENING FROM 1215 PM UNTIL

700 PM CDT.



HAIL TO 1.5 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 70

STATUTE MILES EITHER SIDE OF A LINE FROM 20 MILES NORTHWEST OF

BLOOMINGTON ILLINOIS TO 25 MILES SOUTHEAST OF JACKSON MICHIGAN.

FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU5).



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...STORMS OVER NORTH CENTRAL IL NEWD INTO SRN LAKE

MICHIGAN ARE EXPECTED TO INTENSIFY AND MOVE/DEVELOP SEWD THROUGH THE

AFTERNOON HOURS AS THEY ENCOUNTER A WARMING AND DESTABILIZING AIR

MASS. COLD AIR ALOFT FAVORS SOME STORMS WITH SEVERE HAIL...THOUGH

THE GREATER THREAT IS EXPECTED TO BECOME DAMAGING WINDS AS THE STORM

OUTFLOWS CONGEAL INTO A LINEAR MCS WITHIN THE DEEP AND MODERATELY

STRONG WLY TROPOSPHERIC WINDS.



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

TO 1.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM

MOTION VECTOR 30025.





...IMY

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