Weather Service Report

FXUS65 KMSO 202050

Area Forecast Discussion
National Weather Service Missoula MT
250 PM MDT Fri Jul 20 2018

...A windy Saturday afternoon for much of Western Montana...

.DISCUSSION...Smoke from fires in Washington has gradually
infiltrated the valleys of NW Montana and may drift south
overnight. Fortunately, the passage of a dry cold front overnight
through Saturday will help mix the air and limit the potential for
prolonged smoke in the air. 

This dry cold front is forecast to stall across western Montana 
which will help enhance wind speeds across much of West Central 
and Southwest Montana Saturday afternoon. Sustained winds of 15 to
25 mph with gusts to near 40 mph are expected in many places 
including Missoula and along I-90 towards Garrison Jct. A Wind
Advisory may need to be considered if the impact potential is
determined to be more widespread than presently expected. However,
the prolonged nature of gusty winds will help drive the humidity 
to very low levels in the East Lolo NF and thus we have issued a 
Fire Weather Watch. The front will move south of the area Saturday
evening and winds will gradually weaken as the humidity comes up 
later in the evening.

Sunday will be an absolutely gorgeous day across the Northern
Rockies with temperatures running 5 to 7 degrees below normal.
However, it appears this cooling will be very short lived as the
high pressure ridge to our south steadily gains strength. By 
Tuesday, temperatures will rise right back to near normal and 
then above normal by Wednesday. Models are still showing weak 
waves of monsoonal moisture working their way towards Idaho and 
Montana by mid week. But just as this occurs, both the ECMWF and 
to a greater extent the GFS, show a Canadian trough moving into 
the region and therefore suppressing the ridge. It could be quite
interesting if this solution pans out as it would certainly 
support fairly widespread thunderstorm development across Montana 
and perhaps even parts of North Central Idaho. This type of 
pattern change would also bring another round of below normal 
temperatures late next week.


.AVIATION...Mostly clear skies are expected across the region
today. A dry cold front will bring breezy westerly winds to
aviation sites in western Montana this afternoon and persist 
until sunset. Gusts up to 20 to 25 kts will be common during this 
period. Strong wind gusts are expected at KMSO and KBTM Saturday
afternoon as this cold front stalls over Western Montana.


MT...Fire Weather Watch from Saturday afternoon through Saturday 
     evening East Lolo.



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