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URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 276

NWS STORM PREDICTION CENTER NORMAN OK

955 PM CDT SUN JUN 6 2010



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       NORTHEAST COLORADO

       NORTHWEST KANSAS

       SOUTHWEST NEBRASKA



EFFECTIVE THIS SUNDAY NIGHT AND MONDAY MORNING FROM 955 PM UNTIL

300 AM 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 65

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 40 MILES SOUTH OF

AKRON COLORADO TO 25 MILES EAST SOUTHEAST OF MCCOOK NEBRASKA.

FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU6).



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...THIS SEVERE THUNDERSTORM WATCH REPLACES

SEVERE THUNDERSTORM WATCH NUMBER 274. WATCH NUMBER 274 WILL NOT

BE IN EFFECT AFTER 955 PM CDT. CONTINUE...WW 275...



DISCUSSION...ONGOING CLUSTERS OF SEVERE STORMS WILL LIKELY PERSIST

FOR ANOTHER FEW HOURS AS THE LLJ INCREASES ACROSS WRN KS AND

MOISTURE CONTINUES TO SPREAD NWD NEAR AND ABOVE THE SURFACE.

MODERATE INSTABILITY AND EFFECTIVE BULK SHEAR IN EXCESS OF 50 KT

WILL CONTINUE TO FAVOR EMBEDDED SUPERCELLS WITH LARGE HAIL...WHILE

MERGING STORMS COULD ALSO SUPPORT LARGER CLUSTER DEVELOPMENT AND AN

ATTENDANT THREAT FOR DAMAGING WINDS.  AN ISOLATED TORNADO CANNOT BE

RULED OUT IN THE NEXT 1-2 HOURS...THOUGH GRADUAL STABILIZATION OF

BOUNDARY LAYER AND A TRANSITION FROM CELLS TO CLUSTERS SHOULD TEND

TO OFFSET THE INCREASE IN LOW-LEVEL SHEAR WITH THE LLJ.



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 30025.





...THOMPSON

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