

000 

WWUS20 KWNS 112028

SEL1

SPC WW 112028

MTZ000-NDZ000-SDZ000-WYZ000-120400-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 381

NWS STORM PREDICTION CENTER NORMAN OK

230 PM MDT MON JUN 11 2007



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       PARTS OF EASTERN MONTANA

       MUCH OF WESTERN NORTH DAKOTA

       PARTS OF WESTERN SOUTH DAKOTA

       PARTS OF NORTHEAST WYOMING



EFFECTIVE THIS MONDAY AFTERNOON AND EVENING FROM 230 PM UNTIL

1000 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 85

STATUTE MILES EAST AND WEST OF A LINE FROM 70 MILES NORTHWEST OF

MINOT NORTH DAKOTA TO 30 MILES SOUTH OF MOORCROFT WYOMING.  FOR A

COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE

UPDATE (WOUS64 KWNS WOU1).



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 380...



DISCUSSION...COLD FRONT FROM ND/MT BORDER SWWD INTO NERN WY.  AIR

MASS NOW VERY UNSTABLE AHEAD OF FRONT WITH 40-50 KT OF DEEP LAYER

SHEAR.  THUNDERSTORMS WILL DEVELOP RAPIDLY ALONG/AHEAD OF FRONT NEXT

COUPLE HOURS.  WITH VERY STEEP LAPSE RATES COUPLED WITH SHEAR AND

INSTABILITY...SUPERCELLS ARE LIKELY. VERY LARGE HAIL IS LIKELY WITH

ANY SUPERCELL IN ADDITION TO DAMAGING WINDS.



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 22030.





...HALES

