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URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 266

NWS STORM PREDICTION CENTER NORMAN OK

330 PM CDT MON MAY 9 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       PART OF THE NEBRASKA PANHANDLE

       PARTS OF WESTERN SOUTH DAKOTA

       PARTS OF EASTERN WYOMING



EFFECTIVE THIS MONDAY AFTERNOON AND EVENING FROM 330 PM UNTIL

1000 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 75

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

SOUTHWEST OF TORRINGTON WYOMING TO 60 MILES NORTH NORTHWEST OF

RAPID CITY SOUTH DAKOTA.  FOR A COMPLETE DEPICTION OF THE WATCH

SEE THE ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU6).



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 UPPER IMPULSE MOVING NEWD FROM CENTRAL ROCKIES

TO HIGH PLAINS THIS EVENING WILL INTERACT WITH UPSLOPE FLOW ACROSS

THE WATCH OF MOIST AND INCREASINGLY UNSTABLE AIR MASS.

THUNDERSTORMS DEVELOPING OVER HIGHER TERRAIN SERN WY WILL INCREASE

IN INTENSITY AS THEY MOVE NEWD ACROSS THE WATCH WITH LARGE HAIL AND

DAMAGING WINDS...PARTICULARLY AS STORMS EVOLVE INTO LINE SEGMENTS.



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 22035.





...HALES

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