WATCHES: Severe Thunderstorm Watch Number 484

WWUS20 KWNS 161955
SEL4
SPC WW 161955
COZ000-NEZ000-SDZ000-WYZ000-170300-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 484
NWS STORM PREDICTION CENTER NORMAN OK
155 PM MDT THU JUN 16 2011

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

NORTHEAST COLORADO
WESTERN NEBRASKA
PARTS OF SOUTHWEST AND SOUTH CENTRAL SOUTH DAKOTA
SOUTHEAST WYOMING

EFFECTIVE THIS THURSDAY AFTERNOON AND EVENING FROM 155 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 85
STATUTE MILES NORTH AND SOUTH OF A LINE FROM 25 MILES WEST
NORTHWEST OF CHEYENNE WYOMING TO 30 MILES SOUTHEAST OF VALENTINE
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 483...

DISCUSSION...CONVECTION IS INCREASING OVER SE WY IN ADVANCE OF AN
EJECTING LEAD SPEED MAX ALOFT...IN AN AREA OF LOW-LEVEL UPSLOPE
FLOW. CONTINUED SURFACE HEATING WILL LEAD TO FURTHER
DESTABILIZATION...AND A GRADUAL INCREASE IN STORM COVERAGE/INTENSITY
AS STORMS SPREAD EWD/NEWD THROUGH THE AFTERNOON. OTHER ISOLATED
STORMS COULD EMERGE ACROSS NE CO LATER THIS AFTERNOON...FROM THE
INITIALLY WEAK FRONT RANGE CONVECTION. VERTICAL SHEAR AND
INSTABILITY WILL BE SUFFICIENT FOR SUPERCELLS AND BOWING
SEGMENTS...WITH LARGE HAIL AND DAMAGING WINDS THE MAIN THREATS IN
THE RELATIVELY LARGE TEMPERATURE-DEWPOINT SPREAD ENVIRONMENT.

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 26025.

...THOMPSON

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