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000 

WWUS20 KWNS 071851

SEL3

SPC WW 071851

IAZ000-MNZ000-WIZ000-080200-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 663

NWS STORM PREDICTION CENTER NORMAN OK

155 PM CDT MON JUL 7 2008



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       NORTHERN INTO CENTRAL IOWA

       SOUTH CENTRAL AND SOUTHEAST MINNESOTA

       SOUTHWEST WISCONSIN



EFFECTIVE THIS MONDAY AFTERNOON AND EVENING FROM 155 PM UNTIL 900

PM 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 60

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 35 MILES WEST

NORTHWEST OF DENISON IOWA TO 40 MILES EAST SOUTHEAST OF LA CROSSE

WISCONSIN.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU3).



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...WEAK SHORTWAVE TROUGH IS INTERACTING WITH EXTREMELY

UNSTABLE AIR MASS DEVELOPING ACROSS IA INTO THE NRN MS RIVER VALLEY

THIS AFTERNOON...WITH RESULTANT INCREASE IN THUNDERSTORMS.  DEEP

LAYER SHEAR FROM 35-40 KT WILL SUSTAIN ORGANIZED

UPDRAFTS...INCLUDING BOW ECHOES AND SUPERCELLS...ENHANCING THE

THREATS OF LARGE HAIL AND DAMAGING WINDS AS STORMS MOVE ENEWD

THROUGH THE EVENING.



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 25025.





...EVANS

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