

601 

WWUS20 KWNS 062101

SEL1

SPC WW 062101

MTZ000-070300-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 581

NWS STORM PREDICTION CENTER NORMAN OK

305 PM MDT FRI AUG 6 2010



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       LARGE PART OF CENTRAL AND SOUTHWEST MONTANA



EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 305 PM UNTIL 900

PM MDT.



HAIL TO 1.5 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 130

STATUTE MILES EAST AND WEST OF A LINE FROM 40 MILES EAST

SOUTHEAST OF DILLON MONTANA TO 25 MILES EAST NORTHEAST OF HAVRE

MONTANA.  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 579...WW 580...



DISCUSSION...THUNDERSTORMS ARE INCREASING ACROSS THE HIGHER TERRAIN

OF SWRN MT AHEAD OF A WEAK S/WV TROUGH. WITH STEEP LAPSE RATES ALONG

WITH 30-40KT OF SHEAR...POTENTIAL WILL INCREASE FOR DAMAGING

DOWNBURST WINDS AS STORMS DEVELOP/PROPAGATE ENEWD ACROSS THE LOWER

ELEVATIONS WHERE T/TD SPREADS ARE AROUND 40F.



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

TO 1.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM

MOTION VECTOR 26030.





...HALES

