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URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 578

NWS STORM PREDICTION CENTER NORMAN OK

535 PM CDT THU JUN 30 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       PARTS OF WESTERN NEBRASKA

       PARTS OF SOUTHWEST SOUTH DAKOTA



EFFECTIVE THIS THURSDAY AFTERNOON AND EVENING FROM 535 PM UNTIL

1100 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 45

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

NORTH PLATTE NEBRASKA TO 135 MILES NORTH NORTHWEST OF MULLEN

NEBRASKA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU8).



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.



OTHER WATCH INFORMATION...CONTINUE...WW 577...



DISCUSSION...THUNDERSTORMS CONTINUE TO DEVELOP EWD INTO HIGH PLAINS

AHEAD OF STRONG UPPER TROUGH OVER CO.  WITH A HIGHLY MIXED...MDTLY

UNSTABLE AIR MASS ACROSS THE WATCH AREA...POTENTIAL FOR COLD POOL

GENERATED WIND DAMAGE WILL PERSISTS WITH THE STORMS AND SPREAD N AND

E ACROSS.



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 500. MEAN STORM

MOTION VECTOR 24025.





...HALES

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