

000 

WWUS20 KWNS 252247

SEL0

SPC WW 252247

MTZ000-NDZ000-SDZ000-WYZ000-260500-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 450

NWS STORM PREDICTION CENTER NORMAN OK

450 PM MDT MON JUN 25 2007



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       PARTS OF SOUTHEAST MONTANA

       PARTS OF SOUTHWESTERN NORTH DAKOTA

       SMALL PART OF NORTHWEST SOUTH DAKOTA

       SMALL PART OF NORTHEAST WYOMING



EFFECTIVE THIS MONDAY AFTERNOON AND EVENING FROM 450 PM UNTIL

1100 PM MDT.



HAIL TO 3 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 65

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 40 MILES SOUTHWEST

OF BROADUS MONTANA TO 35 MILES NORTH OF LEMMON SOUTH DAKOTA.  FOR

A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU0).



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...THUNDERSTORMS DEVELOPING IN LOW LEVEL CONVERGENCE JUST

AHEAD OF COLD FRONT ALONG NERN WY/MT BORDER. STRONG DEEP LAYER SHEAR

COUPLED WITH MLCAPES AOA 3000 J/KG SUPPORT SUPERCELLS.  PRIMARY

THREAT WILL BE VERY LARGE HAIL AND DAMAGING DOWNBURST WINDS.

ACTIVITY WILL DEVELOP NEWD ACROSS WATCH AREA DURING THE EVENING.



AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT

TO 3 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 70

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 550. MEAN STORM

MOTION VECTOR 26025.





...HALES

