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152 

WWUS20 KWNS 182310

SEL1

SPC WW 182310

NEZ000-SDZ000-190700-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 711

NWS STORM PREDICTION CENTER NORMAN OK

610 PM CDT TUE AUG 18 2009



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       CENTRAL AND WESTERN NEBRASKA

       CENTRAL SOUTH DAKOTA



EFFECTIVE THIS TUESDAY NIGHT AND WEDNESDAY MORNING FROM 610 PM

UNTIL 200 AM 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 70

STATUTE MILES EAST AND WEST OF A LINE FROM 45 MILES NORTHEAST OF

PIERRE SOUTH DAKOTA TO 10 MILES SOUTHEAST OF IMPERIAL NEBRASKA.

FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU1).



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 709...WW 710...



DISCUSSION...THUNDERSTORMS ARE INCREASING IN COVERAGE ALONG A

SURFACE BOUNDARY FROM WESTERN NEB INTO CENTRAL SD.  THESE STORMS

WILL LIKELY PERSIST THROUGH MUCH OF THE EVENING...IN REGION OF

RATHER COOL TEMPERATURES ALOFT...FAVORABLE EFFECTIVE SHEAR...AND

MODERATE INSTABILITY.  LARGE HAIL AND DAMAGING WINDS WILL BE

POSSIBLE IN STRONGER CORES.



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 27030.





...HART

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