

965 

WWUS20 KWNS 212027

SEL8

SPC WW 212027

IAZ000-MNZ000-220300-



URGENT - IMMEDIATE BROADCAST REQUESTED

TORNADO WATCH NUMBER 488

NWS STORM PREDICTION CENTER NORMAN OK

330 PM CDT SUN JUN 21 2009



THE NWS STORM PREDICTION CENTER HAS ISSUED A

TORNADO WATCH FOR PORTIONS OF



       NORTHERN AND CENTRAL IOWA

       FAR SOUTHERN MINNESOTA



EFFECTIVE THIS SUNDAY AFTERNOON AND EVENING FROM 330 PM UNTIL

1000 PM CDT.



TORNADOES...HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND

GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE

AREAS.



THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 60 STATUTE

MILES NORTH AND SOUTH OF A LINE FROM 50 MILES SOUTHWEST OF

WORTHINGTON MINNESOTA TO 30 MILES NORTHEAST OF CEDAR RAPIDS IOWA.

 FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU8).



REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR

TORNADOES AND 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.



DISCUSSION...THUNDERSTORMS EXPECTED TO INTENSIFY QUICKLY LATE TODAY

ALONG AND JUST SOUTH OF A SURFACE WARM FRONT EXTENDING NW-SE ACROSS

IA.  AIR MASS WILL BE MODERATELY UNSTABLE WITH 30-40 KT EFFECTIVE

SHEAR SUPPORTIVE OF SUPERCELLS AND EVOLUTION INTO SMALL BOW ECHOES.

LOW LEVEL SHEAR WILL BE MORE THAN ADEQUATE FOR A THREAT OF TORNADOES

WITH ADDITIONAL LARGE HAIL/DAMAGING WIND THREATS THROUGH THE MID TO

LATE EVENING.



AVIATION...TORNADOES AND 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 28020.





...EVANS

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