WATCHES: Tornado Watch Number 660

WWUS20 KWNS 142326
SEL0
SPC WW 142326
NEZ000-SDZ000-150700-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 660
NWS STORM PREDICTION CENTER NORMAN OK
525 PM MDT TUE SEP 14 2010

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

WESTERN AND NORTHERN NEBRASKA
SOUTHWEST AND SOUTH CENTRAL SOUTH DAKOTA

EFFECTIVE THIS TUESDAY AFTERNOON AND WEDNESDAY MORNING FROM 525
PM UNTIL 100 AM MDT.

TORNADOES...HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND
GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE
AREAS.

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 80 STATUTE
MILES NORTH AND SOUTH OF A LINE FROM 90 MILES WEST NORTHWEST OF
MULLEN NEBRASKA TO 50 MILES NORTH NORTHEAST OF ONEILL NEBRASKA.
FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH
OUTLINE UPDATE (WOUS64 KWNS WOU0).

REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
TORNADOES AND 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.

DISCUSSION...SCTD AREAS OF TSTMS EXPECTED TO MOVE/DEVELOP ENE ACROSS
WW AREA THOUGH EARLY WED AS WAA AND UPR LVL DIVERGENCE INCREASE
DOWNSTREAM FROM ERN WY/NRN CO UPR IMPULSE. DEEP SHEAR AND
INSTABILITY SHOULD REMAIN FAVORABLE FOR SUPERCELLS THROUGH LATE
TONIGHT...WITH WITH MODERATE STRENGTHENING OF SLY LLJ CONTRIBUTING
TO ENHANCED LOW LVL SHEAR. INCREASING CIN AFTER SUNSET MAY RESULT
IN MOST STORMS BEING SLIGHTLY ELEVATED. BUT COMBINATION OF FAIRLY
RICH MOISTURE WITH INCREASING ASCENT AND LOW LVL SHEAR ALONG STALLED
FRONT ON THE NEB/SD BORDER SUGGESTS A NON-ZERO RISK FOR
TORNADOES...IN ADDITION TO SVR WIND/HAIL.

AVIATION...TORNADOES AND 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 26025.

...CORFIDI

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