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315 

WWUS20 KWNS 201922

SEL6

SPC WW 201922

IAZ000-KSZ000-NEZ000-SDZ000-210200-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 336

NWS STORM PREDICTION CENTER NORMAN OK

220 PM CDT FRI JUN 20 2014



THE NWS STORM PREDICTION CENTER HAS ISSUED A



* SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

  PARTS OF NORTHWESTERN IOWA

  PORTIONS OF NORTHERN KANSAS

  CENTRAL AND EASTERN NEBRASKA

  FAR SOUTHEAST SOUTH DAKOTA



* EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 220 PM UNTIL

  900 PM CDT.



* PRIMARY THREATS INCLUDE...

  SCATTERED LARGE HAIL AND ISOLATED VERY LARGE HAIL EVENTS TO 2

    INCHES IN DIAMETER POSSIBLE

  ISOLATED DAMAGING WIND GUSTS TO 65 MPH POSSIBLE



THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 85

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 50 MILES WEST

SOUTHWEST OF NORTH PLATTE NEBRASKA TO 10 MILES SOUTH SOUTHEAST OF

TEKAMAH NEBRASKA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU6).



PRECAUTIONARY/PREPAREDNESS ACTIONS...



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...ISOLATED THUNDERSTORMS HAVE BEGUN TO DEVELOP ACROSS NEB

ATTM...WITH COVERAGE EXPECTED TO INCREASE MARKEDLY OVER THE NEXT

COUPLE OF HOURS ALONG A WEAK/ADVANCING COOL FRONT.  THE AIRMASS

AHEAD OF THE FRONT HAS BECOME VERY UNSTABLE /MIXED-LAYER CAPE NOW IN

EXCESS OF 3000 J/KG ACROSS MOST OF THE REGION/.  WHILE SHEAR REMAINS

SOMEWHAT MODEST WITH FLOW ALOFT GENERALLY AROUND 30 KT...DEGREE OF

INSTABILITY AND FOCUSED ASCENT INVOF THE FRONT SUGGESTS SCATTERED

STRONGER/MULTICELL STORMS CAPABLE OF PRODUCING LARGE HAIL AND

ISOLATED GUSTY WINDS.



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

TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 55

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM

MOTION VECTOR 26030.





...GOSS

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