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WWUS20 KWNS 162144

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IAZ000-MNZ000-NEZ000-WIZ000-170400-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 482

NWS STORM PREDICTION CENTER NORMAN OK

445 PM CDT FRI JUL 16 2010



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       NORTHERN AND WESTERN IOWA

       SOUTHEAST MINNESOTA

       EASTERN NEBRASKA

       SOUTHWEST WISCONSIN



EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 445 PM UNTIL

1100 PM CDT.



HAIL TO 2.5 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 55

STATUTE MILES EITHER SIDE OF A LINE FROM 10 MILES EAST SOUTHEAST

OF LA CROSSE WISCONSIN TO 55 MILES SOUTHWEST OF COLUMBUS

NEBRASKA.  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.



DISCUSSION...COMBINATION OF WEAK SHORTWAVE TROUGH ALOFT AND STRONG

HEATING HAS RESULTED IN STORMS TO BEGIN DEVELOPING ALONG AN AREA OF

LOW LEVEL CONVERGENCE EXTENDING FROM EASTERN NEB NEWD INTO SERN

MN/SWRN WI. GIVEN DEEP LAYER SHEAR AT 30 TO 40 KT AND MLCAPES FROM

2500 TO 4000 J/KG...SEVERE HAIL AND WIND DAMAGE APPEARS PROBABLE IN

THE MORE INTENSE STORMS.



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

TO 2.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 550. MEAN STORM

MOTION VECTOR 31020.





...IMY

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