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WWUS20 KWNS 232030

SEL4

SPC WW 232030

COZ000-KSZ000-NEZ000-240400-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 614

NWS STORM PREDICTION CENTER NORMAN OK

330 PM CDT THU JUL 23 2009



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       PARTS OF NORTHEAST COLORADO

       PARTS OF NORTHWEST KANSAS

       WESTERN NEBRASKA



EFFECTIVE THIS THURSDAY AFTERNOON AND EVENING FROM 330 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 65

STATUTE MILES EAST AND WEST OF A LINE FROM 40 MILES WEST

NORTHWEST OF VALENTINE NEBRASKA TO 40 MILES SOUTH SOUTHEAST OF

BURLINGTON COLORADO.  FOR A COMPLETE DEPICTION OF THE WATCH SEE

THE ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU4).



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...AIR MASS WITH STRONG HEATING HAS BECOME MDTLY UNSTABLE

WITH MLCAPES AOA 2000 J/KG ACROSS THE WATCH.  EFFECTIVE SHEAR OF

30KT IN NWLY FLOW REGIME WILL SUPPORT ROTATING STORMS.

THUNDERSTORMS ARE DEVELOPING ALONG WESTERN AREA OF GREATEST

INSTABILITY AND WILL MOVE/PROPAGATE SEWD ACROSS THE WATCH.  VERY

LARGE HAIL IS PRIMARY THREAT WITH PARTICULARLY ANY SUPERCELL THAT

DEVELOPS.  DAMAGING DOWNBURSTS WINDS ARE ALSO POSSIBLE AS WELL AS

ISOLATED BRIEF TORNADOS.



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 33025.





...HALES

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