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489 

WWUS20 KWNS 040611

SEL3

SPC WW 040611

IAZ000-KSZ000-MOZ000-NEZ000-041200-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 653

NWS STORM PREDICTION CENTER NORMAN OK

110 AM CDT TUE AUG 4 2009



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       EXTREME SOUTHWEST IOWA

       NORTH CENTRAL AND NORTHEAST KANSAS

       EXTREME NORTHWEST MISSOURI

       SOUTH CENTRAL AND SOUTHEAST NEBRASKA



EFFECTIVE THIS TUESDAY MORNING FROM 110 AM UNTIL 700 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 50

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 40 MILES WEST OF

KEARNEY NEBRASKA TO 30 MILES EAST OF FALLS CITY NEBRASKA.  FOR A

COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE

UPDATE (WOUS64 KWNS WOU3).



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 652...



DISCUSSION...TWO MODES OF CONVECTION SHOULD PERSIST OVERNIGHT...WITH

ELEVATED STORMS DRIVEN BY WAA OVER SE NEB/NE KS/NW MO...AND AN MCS

WITH ASSOCIATED COLD POOL WHICH SHOULD CONTINUE ESEWD FROM

CENTRAL/SRN NEB.  THE WAA STORMS WILL POSE A THREAT FOR LARGE

HAIL...WHILE BOTH DAMAGING WINDS AND LARGE HAIL WILL BE POSSIBLE

WITH THE STORMS MOVING ESEWD ACROSS NEB.  THE CAP STRENGTH IS OF

SOME CONCERN...BUT A RESERVOIR OF STRONG INSTABILITY REMAINS ALONG

THE NEB/KS BORDER REGION IN PROXIMITY TO A STALLED BOUNDARY...THUS

THE SEVERE STORM THREAT COULD PERSIST OVERNIGHT.



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 550. MEAN STORM

MOTION VECTOR 28025.





...THOMPSON

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