WATCHES: Severe Thunderstorm Watch Number 291

WWUS20 KWNS 130010
SEL1
SPC WW 130010
NEZ000-SDZ000-130600-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 291
NWS STORM PREDICTION CENTER NORMAN OK
710 PM CDT TUE MAY 12 2009

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

CENTRAL AND NORTH CENTRAL NEBRASKA
CENTRAL SOUTH DAKOTA

EFFECTIVE THIS TUESDAY NIGHT AND WEDNESDAY MORNING FROM 710 PM
UNTIL 100 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 10 MILES EAST OF NORTH
PLATTE NEBRASKA TO 40 MILES NORTHWEST OF ABERDEEN SOUTH DAKOTA.
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 289...WW 290...

DISCUSSION...ONGOING SEVERE STORMS/SUPERCELLS FROM CENTRAL SD INTO
CENTRAL NEB WILL LIKELY CONTINUE THROUGH EARLY TONIGHT IN ADVANCE OF
A STRONG MID LEVEL TROUGH AND ASSOCIATED SURFACE COLD FRONT. STEEP
MID LEVEL LAPSE RATES AND 0-6 KM BULK SHEAR OF 45-60 KT WILL SUPPORT
A CONTINUED THREAT FOR SUPERCELLS AND SMALL BOWS AS THE BELT OF
ASCENT SPREADS FROM W TO E ACROSS SD AND NRN NEB...DESPITE SOMEWHAT
LIMITED MOISTURE.

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 27035.

...THOMPSON

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