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379 

WWUS20 KWNS 090126

SEL9

SPC WW 090126

COZ000-NEZ000-WYZ000-090600-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 679

NWS STORM PREDICTION CENTER NORMAN OK

730 PM MDT SAT AUG 8 2009



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       NORTHEAST COLORADO

       NEBRASKA PANHANDLE

       SOUTHEAST WYOMING



EFFECTIVE THIS SATURDAY NIGHT FROM 730 PM UNTIL MIDNIGHT MDT.



HAIL TO 2.5 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 55

STATUTE MILES EAST AND WEST OF A LINE FROM 15 MILES NORTH

NORTHEAST OF CHADRON NEBRASKA TO 75 MILES SOUTHWEST OF SIDNEY

NEBRASKA.  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 678...



DISCUSSION...WELL DEFINED SHORTWAVE TROUGH MOVING NEWD ACROSS THE

CENTRAL ROCKIES WILL CONTINUE TO SUPPORT STRONG/SEVERE THUNDERSTORM

DEVELOPMENT OVER THE HIGH PLAINS THROUGH THE EVENING.  AIR MASS

REMAINS QUITE MOIST INTO WRN NEB/NERN CO AND WILL SUSTAIN MARGINAL

INSTABILITY.  SHEAR WILL BE SUPPORTIVE OF SUPERCELLS...ENHANCING THE

RISK OF LARGE HAIL GIVEN VERY STEEP MID LEVEL LAPSE RATES.



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

TO 2.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60

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

MOTION VECTOR 25030.





...EVANS

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