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253 

WWUS20 KWNS 200634

SEL5

SPC WW 200634

ILZ000-INZ000-KYZ000-201200-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 485

NWS STORM PREDICTION CENTER NORMAN OK

235 AM EDT SAT JUN 20 2009



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       SOUTHEAST ILLINOIS

       SOUTHERN INDIANA

       NORTHERN KENTUCKY



EFFECTIVE THIS SATURDAY MORNING FROM 235 AM UNTIL 800 AM EDT.



HAIL TO 1 INCH 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 35

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

NORTHEAST OF LOUISVILLE KENTUCKY TO 20 MILES SOUTHWEST OF MOUNT

VERNON ILLINOIS.  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.



OTHER WATCH INFORMATION...CONTINUE...WW 483...WW 484...



DISCUSSION...COLD FRONT ASSOCIATED WITH WI/IL UPR TROUGH HAS

ACCELERATED ESE IN THE PAST SEVERAL HOURS AND OVERTAKEN EXISTING

SW-NE CONFLUENCE BAND AND ASSOCIATED TSTMS.  THIS HAS RESULTED IN

SOME INTENSIFICATION OF STORMS ALONG THE FRONT.  40-50 KT MEAN LOW

TO MID LVL UNIDIRECTIONAL WLY FLOW ON S SIDE OF TROUGH WILL REMAIN

OVER FRONTAL ZONE AND MAINTAIN THREAT FOR FORWARD-PROPAGATING/BOWING

SEGMENTS WITH ISOLD DMGG WIND GUSTS...DESPITE TIME OF DAY.



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

TO 1 INCH. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60 KNOTS.

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

VECTOR 28040.





...CORFIDI

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