WATCHES: Severe Thunderstorm Watch Number 454

WWUS20 KWNS 111934
SEL4
SPC WW 111934
COZ000-NEZ000-120300-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 454
NWS STORM PREDICTION CENTER NORMAN OK
135 PM MDT SUN JUL 11 2010

THE NWS STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

FAR NORTHEAST COLORADO
WESTERN NEBRASKA INCLUDING THE PANHANDLE

EFFECTIVE THIS SUNDAY AFTERNOON AND EVENING FROM 135 PM UNTIL 900
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 75
STATUTE MILES EAST AND WEST OF A LINE FROM 35 MILES EAST
NORTHEAST OF CHADRON NEBRASKA TO 45 MILES WEST OF IMPERIAL
NEBRASKA. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU4).

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 450...WW 451...WW
452...WW 453...

DISCUSSION...TSTMS ARE EXPECTED TO INCREASE IN COVERAGE AND
INTENSITY THIS AFTERNOON AND EVENING IN ADVANCE OF SHORT WAVE TROUGH
PROGRESSING EWD FROM ERN WY. THOUGH BOUNDARY LAYER IS NOT
PARTICULARLY MOIST...THE PRESENCE OF STEEP LOW TO MIDLEVEL LAPSE
RATES IS RESULTING IN A MODERATELY UNSTABLE AIR MASS WITH MLCAPE OF
1000-1500 J/KG. WHEN COMBINED WITH 40-45 KT OF DEEP WNWLY
SHEAR...SETUP WILL FAVOR THE DEVELOPMENT OF HIGH-BASED SUPERCELLS
AND BOWING STORM CLUSTERS WITH THE THREAT FOR DAMAGING WINDS AND
LARGE 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 500. MEAN STORM
MOTION VECTOR 28030.

...MEAD

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