URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 557
NWS STORM PREDICTION CENTER NORMAN OK
500 PM MDT MON JUL 6 2009
THE NWS STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF
SOUTHEASTERN MONTANA
NORTHEASTERN WYOMING
EFFECTIVE THIS MONDAY AFTERNOON AND EVENING FROM 500 PM UNTIL
1000 PM MDT.
HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 80
MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.
THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 70
STATUTE MILES EITHER SIDE OF A LINE FROM 60 MILES SOUTH OF
GILLETTE WYOMING TO 30 MILES NORTH NORTHEAST OF MILES CITY
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 553...WW 554...WW
555...WW 556...
DISCUSSION...LINE OF DEVELOPING STORMS...ASSOCIATED WITH AN UPPER
LEVEL IMPULSE...IS EXPECTED TO MOVE ENEWD AT 35 KT THROUGH PORTIONS
OF SERN MT/NERN WY DURING THE EVENING HOURS. A WARM FRONT WAS
LOCATED NEAR THE WY/MT BORDER...WITH ELY BOUNDARY LAYER WINDS AND
MODERATE INSTABILITY FAVORABLE FOR A FORWARD-PROPAGATING MCS ACROSS
SERN MT. DESPITE WEAKER DEEP LAYER SHEAR IN NERN WY...THE ORGANIZED
OUTFLOW AND 25-30 DEGREE TEMPERATURE/DEWPOINT SPREADS WILL ALSO
SUPPORT STRONG TO SEVERE WIND GUSTS.
AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 70
KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 450. MEAN STORM
MOTION VECTOR 25035.
...IMY
Hazard Tornadoes EF2+ Tornadoes
Likelihood Low Low
Severe Wind 65 kt+ Wind
Moderate Moderate
Severe Hail 2"+ Hail
Moderate Low
(trying to forget about everything happening in 3's)!!!
