WATCHES: Severe Thunderstorm Watch Number 547

WWUS20 KWNS 241954
SEL7
SPC WW 241954
COZ000-MTZ000-NEZ000-SDZ000-WYZ000-250300-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 547
NWS STORM PREDICTION CENTER NORMAN OK
155 PM MDT FRI JUN 24 2011

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

NORTHEAST COLORADO
SOUTHEAST MONTANA
WESTERN NEBRASKA PANHANDLE
WESTERN SOUTH DAKOTA
CENTRAL AND EASTERN WYOMING

EFFECTIVE THIS FRIDAY 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 105
STATUTE MILES EAST AND WEST OF A LINE FROM 45 MILES SOUTH OF
CHEYENNE WYOMING TO 40 MILES NORTH NORTHEAST OF BROADUS MONTANA.
FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH
OUTLINE UPDATE (WOUS64 KWNS WOU7).

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 544...WW 545...WW 546...

DISCUSSION...TSTMS ARE DEVELOPING ALONG THE FAVORED TERRAIN OF WY
THIS AFTERNOON IN ADVANCE OF MIDLEVEL IMPULSE APPROACHING FROM THE
W. A FURTHER INCREASE IN LARGE-SCALE FORCING AND LOW-LEVEL UPSLOPE
FLOW SHOULD SUPPORT ADDITIONAL STORM DEVELOPMENT ACROSS PARTS OF
NERN CO...SERN MT AND WRN SD. GIVEN THE PRESENCE OF STEEP LAPSE
RATES...BOUNDARY-LAYER DEWPOINTS IN THE 50S AND 40-50 KT OF DEEP WLY
SHEAR...SETUP WILL FAVOR THE DEVELOPMENT OF SUPERCELLS CAPABLE OF
MAINLY LARGE HAIL AND DAMAGING WINDS. WHILE A TORNADO IS POSSIBLE
LATE THIS AFTERNOON INTO EVENING...A RELATIVELY WEAK LOW-LEVEL WIND
FIELD /AND RESULTANT MARGINAL NEAR-GROUND SPEED SHEAR/ IS EXPECTED
TO PRECLUDE A MORE ROBUST THREAT.

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 25030.

...MEAD

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