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000 

WWUS20 KWNS 222019

SEL7

SPC WW 222019

IAZ000-KSZ000-NEZ000-230400-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 637

NWS STORM PREDICTION CENTER NORMAN OK

320 PM CDT WED AUG 22 2007



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       SOUTHWEST IOWA

       NORTHWEST INTO NORTH CENTRAL KANSAS

       CENTRAL AND EASTERN NEBRASKA



EFFECTIVE THIS WEDNESDAY AFTERNOON AND EVENING FROM 320 PM UNTIL

1100 PM 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 70

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 30 MILES WEST

NORTHWEST OF MCCOOK NEBRASKA TO 30 MILES SOUTHEAST OF OMAHA

NEBRASKA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU7).



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.



DISCUSSION...THUNDERSTORMS ARE EXPECTED TO CONTINUE INCREASING IN

COVERAGE AND INTENSITY...PRIMARILY ALONG AND NORTH OF E-W ORIENTED

SURFACE FRONT...ACROSS WW THROUGH THE EVENING ALONG NOSE OF SSWLY

LLJ.  AIR MASS IS MODERATE TO STRONGLY UNSTABLE WITH EFFECTIVE SHEAR

FROM 20-30 KT SUPPORTING A FEW MORE ORGANIZED STORMS.  LARGE HAIL

WILL BE PRIMARY SEVERE THREAT...ALTHOUGH ISOLATED DAMAGING WINDS IS

ALSO EXPECTED.



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 26015.





...EVANS

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