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590 

WWUS20 KWNS 291353

SEL4

SPC WW 291353

IAZ000-ILZ000-INZ000-MOZ000-LMZ000-292100-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 394

NWS STORM PREDICTION CENTER NORMAN OK

855 AM CDT SUN MAY 29 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       SOUTHEAST IOWA

       NORTHERN ILLINOIS

       NORTHWEST INDIANA

       EXTREME NORTHEAST MISSOURI

       LAKE MICHIGAN



EFFECTIVE THIS SUNDAY MORNING AND AFTERNOON FROM 855 AM UNTIL 400

PM 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 65

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 55 MILES SOUTH

SOUTHWEST OF CEDAR RAPIDS IOWA TO 10 MILES NORTH OF VALPARAISO

INDIANA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU4).



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...AN ORGANIZING LINE OF THUNDERSTORMS OVER IA IS FORECAST

TO ACCELERATE AND TRACK EAST-NORTHEASTWARD ACROSS THE WATCH AREA

TODAY.  RAPID LOW LEVEL DESTABILIZATION AHEAD OF THE

STORMS...COUPLED WITH INCREASING MESOSCALE ORGANIZATION...WILL POSE

A RISK OF A LONG-LIVED BOW ECHO AND RESULTING DERECHO.  STORMS MAY

AFFECT THE CHI METRO AREA AS EARLY AS 18Z.



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 550. MEAN STORM

MOTION VECTOR 25040.





...HART

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