

007 

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

