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559 

WWUS20 KWNS 282038

SEL5

SPC WW 282038

COZ000-KSZ000-290400-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 815

NWS STORM PREDICTION CENTER NORMAN OK

240 PM MDT SUN AUG 28 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       NORTHEAST COLORADO

       NORTHWEST KANSAS



EFFECTIVE THIS SUNDAY AFTERNOON AND EVENING FROM 240 PM UNTIL

1000 PM MDT.



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 40

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 80 MILES EAST OF

GOODLAND KANSAS TO 50 MILES WEST OF BURLINGTON COLORADO.  FOR A

COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE

UPDATE (WOUS64 KWNS WOU5).



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...INTENSE TSTMS HAVE RECENTLY DEVELOPED AT THE

INTERSECTION OF A SWWD-MOVING OUTFLOW BOUNDARY AND WEAK WIND SHIFT.

AMBIENT THERMODYNAMIC ENVIRONMENT IS CHARACTERIZED BY STEEP LAPSE

RATES...A DEEP...WELL-MIXED SUB-CLOUD LAYER AND MLCAPE OF 1000-2000

J/KG.  AS SUCH...SETUP IS QUITE FAVORABLE FOR THE DEVELOPMENT OF

STRONG DOWNDRAFTS AS EVIDENCED BY A RECENT WIND GUST TO 72 MPH AT

COLBY KS.  EXPECT ADDITIONAL STORMS TO DEVELOP WWD/SWWD ACROSS THE

WATCH AREA LATE THIS AFTERNOON INTO EVENING WITH A CONTINUED RISK

FOR DAMAGING WINDS AND HAIL.



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 550. MEAN STORM

MOTION VECTOR 36020.





...MEAD

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