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URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 439

NWS STORM PREDICTION CENTER NORMAN OK

300 PM CDT SAT JUL 3 2010



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       MUCH OF WESTERN NEBRASKA

       PARTS OF SOUTHWEST SOUTH DAKOTA



EFFECTIVE THIS SATURDAY AFTERNOON AND EVENING FROM 300 PM UNTIL

1000 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 85

STATUTE MILES EAST AND WEST OF A LINE FROM 30 MILES EAST

SOUTHEAST OF SIDNEY NEBRASKA TO 75 MILES NORTH NORTHEAST OF

CHADRON NEBRASKA.  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...THUNDERSTORMS ARE INCREASING IN NUMBER/INTENSITY ACROSS

THE HIGHER TERRAIN OF SERN WY.  WITH GREATER INSTABILITY TO THE E

ACROSS THE WATCH AREA COUPLED WITH CONTINUED HEATING...SEVERE

THUNDERSTORMS ARE LIKELY TO DEVELOPS EWD WITH POTENTIAL FOR

SUPERCELLS. LARGE HAIL WILL BE THE PRIMARY THREAT

INITIALLY...PARTICULARLY WITH SUPERCELLS. HOWEVER STEEP LAPSE RATES

AND RELATIVELY HIGH BASES WILL LEAD TO DAMAGING WIND POTENTIAL.



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 500. MEAN STORM

MOTION VECTOR 25020.





...HALES

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