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000 

WWUS20 KWNS 261139

SEL9

SPC WW 261139

IAZ000-MNZ000-NEZ000-SDZ000-261800-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 609

NWS STORM PREDICTION CENTER NORMAN OK

640 AM CDT THU JUN 26 2008



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       CENTRAL INTO NORTHWEST IOWA

       EXTREME SOUTHWEST MINNESOTA

       NORTHEAST NEBRASKA

       SOUTHEAST SOUTH DAKOTA



EFFECTIVE THIS THURSDAY MORNING AND AFTERNOON FROM 640 AM UNTIL

100 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 NORTH AND SOUTH OF A LINE FROM 60 MILES WEST

SOUTHWEST OF MITCHELL SOUTH DAKOTA TO 40 MILES NORTHEAST OF

KNOXVILLE 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.



DISCUSSION...INTENSE THUNDERSTORMS EXPECTED TO INCREASE IN COVERAGE

AND INTENSITY ACROSS WW THROUGH THE MORNING AS SLOW MOVING SHORTWAVE

TROUGH INCREASES ASCENT.  FEED OF EXTREMELY UNSTABLE AIR MASS TO THE

SOUTHWEST OF DEVELOPING COMPLEX SHOULD MAINTAIN THREAT OF LARGE HAIL

ALONG WITH ISOLATED DAMAGING WINDS.  SHEAR WILL SUSTAIN SUPERCELL

AND BOWING STRUCTURES AS THIS ACTIVITY TRACKS SEWD ALONG SE-NW

ORIENTED OUTFLOW BOUNDARY INTO CENTRAL IA.



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 30025.





...EVANS

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