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URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 342

NWS STORM PREDICTION CENTER NORMAN OK

1230 PM CDT FRI JUN 18 2010



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       MUCH OF EASTERN IOWA

       MUCH OF NORTHERN ILLINOIS

       PARTS OF NORTHWESTERN INDIANA

       SMALL PART OF NORTHEAST MISSOURI

       PARTS OF SOUTHERN WISCONSIN

       LAKE MICHIGAN



EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 1230 PM UNTIL

700 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 90

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 30 MILES EAST OF

MEIGS FIELD ILLINOIS TO 45 MILES SOUTHWEST OF CEDAR RAPIDS IOWA.

FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU2).



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...THIS SEVERE THUNDERSTORM WATCH REPLACES

SEVERE THUNDERSTORM WATCH NUMBER 341. WATCH NUMBER 341 WILL NOT

BE IN EFFECT AFTER 1230 PM CDT.



DISCUSSION...SQUALL LINE ERN IA WILL CONTINUE ACROSS THE WATCH AREA

WHERE AIR MASS IS BECOMING VERY UNSTABLE.  DAMAGING WINDS WILL

CONTINUE TO BE ASSOCIATED WITH THE LINE.  ADDITIONAL SEVERE STORMS

ARE EXPECTED TO DEVELOP DURING THE AFTERNOON ACROSS SRN IA VICINITY

BOUNDARY FROM CURRENT ACTIVITY AND ALSO MOVE EWD ACROSS THE WATCH

AREA BY THIS EVENING.



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 500. MEAN STORM

MOTION VECTOR 26035.





...HALES

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