

286 

WWUS20 KWNS 191839

SEL9

SPC WW 191839

IAZ000-KSZ000-MOZ000-NEZ000-200200-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 479

NWS STORM PREDICTION CENTER NORMAN OK

140 PM CDT FRI JUN 19 2009



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       SOUTHERN IOWA

       EXTREME NORTHEAST KANSAS

       NORTHERN MISSOURI

       SOUTHEAST NEBRASKA



EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 140 PM UNTIL 900

PM CDT.



HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 80

MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.



THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 60

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 25 MILES SOUTH OF

SHENANDOAH IOWA TO 15 MILES EAST NORTHEAST OF OTTUMWA IOWA.  FOR

A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU9).



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 477...WW 478...



DISCUSSION...STORMS ARE GRADUALLY INCREASING FROM EXTREME NORTHEAST

KS INTO SOUTHEAST NE...AND INTENSIFICATION OF ACTIVITY IS LIKELY

THIS AFTERNOON IN RESPONSE TO UPPER SHORT WAVE TROUGH APPROACHING

FROM THE WEST.  ENVIRONMENT IS VERY UNSTABLE WITH MLCAPE TO 3000

J/KG...AND STRONG SWLY FLOW ALOFT IS RESULTING IN DEEP LAYER SHEAR

OF 40-50 KT.  THIS WILL PROMOTE DEVELOPMENT OF STORMS WITH SUPERCELL

AND BOW ECHO STRUCTURES...WITH ACTIVITY EVENTUALLY DEVELOPING INTO A

FORWARD-PROPAGATING MCS AS COLD POOLS MERGE AND GROW UPSCALE.

PRIMARY THREAT EXPECTED TO BE DAMAGING WIND GUSTS ALTHOUGH LARGE

HAIL AND AN ISOLATED TORNADO ARE ALSO POSSIBLE.



AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT

TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 70

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 550. MEAN STORM

MOTION VECTOR 24035.





...WEISS

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