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755 

WWUS20 KWNS 251749

SEL9

SPC WW 251749

IAZ000-ILZ000-WIZ000-260000-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 509

NWS STORM PREDICTION CENTER NORMAN OK

1250 PM CDT THU JUN 25 2009



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       EASTERN IOWA

       NORTHWEST ILLINOIS

       EXTREME SOUTHWEST WISCONSIN



EFFECTIVE THIS THURSDAY AFTERNOON AND EVENING FROM 1250 PM UNTIL

700 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 70

STATUTE MILES EAST AND WEST OF A LINE FROM 35 MILES NORTHWEST OF

DUBUQUE IOWA TO 25 MILES SOUTH OF PEORIA ILLINOIS.  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.



OTHER WATCH INFORMATION...CONTINUE...WW 508...



DISCUSSION...THUNDERSTORMS EXPECTED TO CONTINUE INCREASING IN

COVERAGE AND INTENSITY GIVEN VERY UNSTABLE AIR MASS AS AREA IS

SKIRTED BY LARGE SCALE ASCENT ASSOCIATED WITH GREAT LAKES UPPER

TROUGH.  LOW LEVEL SHEAR/FLOW IS WEAK...THOUGH UPPER LEVEL NWLY

WINDS SHOULD ENHANCE THE POTENTIAL FOR A FEW SEVERE

STORMS...INCLUDING ORGANIZATION INTO CLUSTERS/LINES.  LARGE HAIL AND

DAMAGING WINDS WILL BE PRIMARY SEVERE THREATS AS STORMS PERSIST INTO

THE EVENING.



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 500. MEAN STORM

MOTION VECTOR 32015.





...EVANS

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