

000 

WWUS20 KWNS 102205

SEL3

SPC WW 102205

NEZ000-SDZ000-110400-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 583

NWS STORM PREDICTION CENTER NORMAN OK

505 PM CDT FRI AUG 10 2007



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       NORTH CENTRAL NEBRASKA

       CENTRAL SOUTH DAKOTA



EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 505 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 55

STATUTE MILES EAST AND WEST OF A LINE FROM 50 MILES NORTH

NORTHWEST OF PIERRE SOUTH DAKOTA TO 35 MILES SOUTH SOUTHEAST OF

MULLEN NEBRASKA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU3).



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 580...WW 581...WW 582...



DISCUSSION...THUNDERSTORMS ARE BEGINNING TO DEVELOP ALONG A N-S

TROUGH ACROSS WRN SD INTO NW NEB...AND OTHER DEVELOPMENT MAY OCCUR

ALONG A REMNANT OUTFLOW BOUNDARY ACROSS NRN NEB.  STRONG INSTABILITY

IS PRESENT ALONG THE OUTFLOW AND E OF THE SURFACE TROUGH...AND

VERTICAL SHEAR IS SUFFICIENT FOR SUPERCELLS.  LARGE HAIL AND

DAMAGING WINDS SHOULD BE THE MAIN THREATS THROUGH THE EVENING AS

CONVECTION MOVES EWD INTO CENTRAL SD/NEB.



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 550. MEAN STORM

MOTION VECTOR 28020.





...THOMPSON

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