WATCHES: Severe Thunderstorm Watch Number 160

WWUS20 KWNS 220334
SEL0
SPC WW 220334
NEZ000-SDZ000-220900-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 160
NWS STORM PREDICTION CENTER NORMAN OK
1035 PM CDT SAT APR 21 2007

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

NORTH CENTRAL INTO PART OF NORTHEASTERN NEBRASKA
SOUTHEASTERN SOUTH DAKOTA

EFFECTIVE THIS SATURDAY NIGHT AND SUNDAY MORNING FROM 1035 PM
UNTIL 400 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 60
STATUTE MILES EAST AND WEST OF A LINE FROM 45 MILES NORTH OF
BROOKINGS SOUTH DAKOTA TO 35 MILES WEST OF BURWELL NEBRASKA. FOR
A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH
OUTLINE UPDATE (WOUS64 KWNS WOU0).

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...THIS SEVERE THUNDERSTORM WATCH REPLACES
TORNADO WATCH NUMBER 154...TORNADO WATCH NUMBER 155. WATCH NUMBER
154 155 WILL NOT BE IN EFFECT AFTER 1035 PM CDT. CONTINUE...WW
157...WW 158...WW 159...

DISCUSSION...MODERATE INSTABILITY AND STRONG EFFECTIVE BULK SHEAR
WILL PERSIST ACROSS MUCH WW TONIGHT. STORMS WILL LIKELY REMAIN
SLIGHTLY ELEVATED...THOUGH SUPERCELLS AND SMALL BOWING STRUCTURES
CAN BE EXPECTED. THIS WILL INCREASE THE THREAT OF LARGE
HAIL...ALONG WITH ISOLATED DAMAGING WINDS.

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.

..EVANS

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