WATCHES: Tornado Watch Number 656

WWUS20 KWNS 131943
SEL6
SPC WW 131943
IAZ000-KSZ000-NEZ000-140400-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 656
NWS STORM PREDICTION CENTER NORMAN OK
240 PM CDT MON SEP 13 2010

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

SOUTHWEST IOWA
NORTHERN KANSAS
SOUTHERN AND CENTRAL NEBRASKA

EFFECTIVE THIS MONDAY AFTERNOON AND EVENING FROM 240 PM UNTIL
1100 PM CDT.

TORNADOES...HAIL TO 2.5 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 70 STATUTE
MILES NORTH AND SOUTH OF A LINE FROM 15 MILES NORTH NORTHWEST OF
MCCOOK NEBRASKA TO 15 MILES EAST NORTHEAST OF FALLS CITY
NEBRASKA. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU6).

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.

OTHER WATCH INFORMATION...CONTINUE...WW 655...

DISCUSSION...TSTMS ARE EXPECTED TO INCREASE IN NUMBER AND INTENSITY
THIS AFTERNOON AND EVENING FROM THE VICINITY OF A SURFACE LOW NW OF
HLC EWD ALONG EITHER SIDE OF A STATIONARY BOUNDARY SITUATED NEAR THE
NEB/KS BORDER. THE COMBINATION OF BOUNDARY LAYER DEWPOINTS IN THE
MID 60S TO LOWER 70S AND STEEP MIDLEVEL LAPSE RATES IS YIELDING A
MODERATE TO STRONGLY UNSTABLE AIR MASS WITH MLCAPE OF 2000-3000+
J/KG AND A WEAKENING CAP. DEEP-LAYER SHEAR IS ALREADY SUPPORTIVE OF
SUPERCELLS AND AS A SLY LLJ INCREASES TO 30+ KT TOWARD
14/00Z...LOW-LEVEL SHEAR WILL ACCORDING STRENGTHEN. AS SUCH...THE
INITIAL HAZARDS WILL BE LARGE HAIL AND DAMAGING WINDS.
HOWEVER...THE POTENTIAL FOR A FEW TORNADOES WILL INCREASE BY LATE
AFTERNOON THROUGH THIS EVENING.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 2.5 INCHES. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
500. MEAN STORM MOTION VECTOR 29025.

...MEAD

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