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173 

WWUS20 KWNS 300214

SEL9

SPC WW 300214

IAZ000-300800-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 109

NWS STORM PREDICTION CENTER NORMAN OK

915 PM CDT THU APR 29 2010



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       CENTRAL IOWA



EFFECTIVE THIS THURSDAY NIGHT AND FRIDAY MORNING FROM 915 PM

UNTIL 300 AM 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 50

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

SHENANDOAH IOWA TO 20 MILES EAST SOUTHEAST OF MASON CITY IOWA.

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 108...



DISCUSSION...BROKEN BAND OF STRONG/SEVERE STORMS WILL LIKELY PERSIST

FOR SEVERAL MORE HOURS AS STORMS FORM ALONG THE STALLED BOUNDARY IN

IA...AND ADDITIONAL CONVECTION MOVES NEWD FROM SE NEB/SW IA.  THE

ENVIRONMENT WILL BE FAVORABLE FOR SOME EMBEDDED SUPERCELL STRUCTURES

FOR THE NEXT FEW HOURS WHICH WILL LOCALLY ENHANCE THE HAIL

THREAT...AND STORM MERGERS LATER COULD ALSO RESULT IN A FEW BOWING

SEGMENTS WITH DAMAGING WINDS.



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 24035.





...THOMPSON

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