

498 

WWUS20 KWNS 091018

SEL0

SPC WW 091018

IAZ000-NEZ000-091700-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 680

NWS STORM PREDICTION CENTER NORMAN OK

520 AM CDT SUN AUG 9 2009



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       WESTERN IOWA

       CENTRAL AND EASTERN NEBRASKA



EFFECTIVE THIS SUNDAY MORNING FROM 520 AM UNTIL NOON 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 45

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 35 MILES NORTHWEST

OF KEARNEY NEBRASKA TO 5 MILES SOUTH SOUTHEAST OF DENISON IOWA.

FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU0).



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...TSTMS HAVE FORMED INVOF WSW-ENE 850 COLD FRONT MOVING

SLOWLY SWD ACROSS CNTRL NEB.  DEEP EML ABOVE FRONTAL SFC AND

PRESENCE OF ELEVATED MOIST LAYERS SUGGEST POTENTIAL FOR SUFFICIENT

ELEVATED INSTABILITY TO SUPPORT LARGE HAIL AND POSSIBLY DMGG WINDS

GIVEN 40 KT WSWLY CLOUD-LAYER SHEAR.



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 25030.





...CORFIDI

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