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573 

WWUS20 KWNS 102202

SEL4

SPC WW 102202

COZ000-NEZ000-110400-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 764

NWS STORM PREDICTION CENTER NORMAN OK

400 PM MDT WED AUG 10 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       EXTREME NORTHEAST COLORADO

       WESTERN AND PARTS OF CENTRAL NEBRASKA



EFFECTIVE THIS WEDNESDAY AFTERNOON AND EVENING FROM 400 PM UNTIL

1000 PM MDT.



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 85

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

NORTHEAST OF CHADRON NEBRASKA TO 20 MILES WEST SOUTHWEST OF

IMPERIAL NEBRASKA.  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...STRONG/SEVERE STORMS HAVE DEVELOPED FROM EXTREME SWRN

SD INTO THE WRN NEBRASKA PANHANDLE...WITHIN LOW LEVEL INSTABILITY

AXIS OVER THE REGION WHERE MLCAPE EXCEEDS 1000 J/KG.  WIND PROFILES

EXHIBIT VEERING WITH HEIGHT AND STRONG WESTERLY FLOW ABOVE 3-4

KM...CONTRIBUTING TO DEEP LAYER SHEAR 40-50 KT.  THIS WILL SUPPORT

DEVELOPMENT OF A FEW SUPERCELLS WITH POTENTIAL TO PRODUCE PRIMARILY

LARGE HAIL AND POSSIBLY STRONG WIND GUSTS.



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 450. MEAN STORM

MOTION VECTOR 31025.





...WEISS

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