WATCHES: Severe Thunderstorm Watch Number 577

WWUS20 KWNS 100116
SEL7
SPC WW 100116
NEZ000-SDZ000-100500-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 577
NWS STORM PREDICTION CENTER NORMAN OK
820 PM CDT THU AUG 9 2007

THE NWS STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

NORTHEAST NEBRASKA
SOUTHEAST SOUTH DAKOTA

EFFECTIVE THIS THURSDAY NIGHT FROM 820 PM UNTIL MIDNIGHT 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 50
STATUTE MILES NORTH AND SOUTH OF A LINE FROM 55 MILES WEST
SOUTHWEST OF YANKTON SOUTH DAKOTA TO 40 MILES NORTHEAST OF
NORFOLK NEBRASKA. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU7).

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 576...

DISCUSSION...BOW ECHO IS ORGANIZING OVER NORTHEAST NEB IN REGION OF
EXTREME INSTABILITY AND FAVORABLE DEEP LAYER VERTICAL SHEAR. THIS
COMPLEX OF STORMS MAY POSE A CONTINUED RISK OF DAMAGING WINDS FOR
ANOTHER 2-3 HOURS AS IT TRACKS EASTWARD ACROSS WATCH AREA.

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 27030.

..HART

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