Bigfork, Montana 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

557
FXUS65 KMSO 011114
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
414 AM MST Sun Nov 1 2026

.DISCUSSION...

-  Valley rain and mountain snow expected through Monday morning,
   focused along and south of I-90. Northwest Montana stays
   mostly dry.

-  High pressure bringing stable conditions and valley fog next
   week.

-  Potential return to unsettled pattern with chances for mountain
   snow by next weekend (Nov. 7-8).

What has changed with today`s system? Not a whole lot. So far the
rainfall amounts have ranged between 0.01 and 0.10" south of
Hamilton. A fairly unexpected shortwave brought rain showers
amounting up to 0.24" from McCall north and west to Lewiston,
Idaho. Areas from Lemhi County east and north will receive the
highest precipitation amounts ranging from 0.25 to 0.40" through
Monday morning. Some snow accumulation is expected at the higher
elevation mountain passes through tonight.

With skies partially clearing from northwest Montana southwards
as the system shifts off to the east tonight, fog and low cloud
development are possible. With not much mixing expected to occur
on Monday, the boundary layer moisture is expected to remain high
that by nightfall, and more fog or low clouds will be possible.
Rinse and repeat this several times through Wednesday. If clouds
end up hanging around some locations, high temperatures could end
up only getting into the mid to upper 40s rather than the 50s.

A quick-moving shortwave trough will bring a chance for showers on
Thursday. Light snowfall accumulation is possible from the Idaho
Panhandle to the northern Clearwater Mountains and across
northwest Montana down to 5000 feet. There is a 25 to 35 percent
chance for rain showers from central Idaho east and north to the
Glacier Region.

Yet another trough passage may occur on Friday. Our clustering
tool shows that at least 50% of the ensemble members have some
sort of wave passage. After this, the clusters depict a very large
amplitude ridge encompassing the region. This would support above
average temperatures. As for precipitation, around 51% of the
clusters show a flatter looking ridge which would support more
clouds and possibly moisture moving into the Idaho Panhandle and
northwest Montana by Sunday. The NBM, which has well over 100
weather model members from around the world, kind of supports this
idea and has a 20 to 30% probability of precipitation of 0.01" or
more occurring by the 8th.

The pattern has an El Nino look to it with deep troughing over
the northeast Pacific. This acts to advect milder air into the
western U.S. The caveats for the Northern Rockies: We are getting
into the time of year when the effects of the sun become weaker
and weaker. This may translate to the increase of low clouds and
fog that may not dissipate very fast. While Pacific trough
passages can give us sporadic precipitation, cloud cover can
prevent us from getting to full potential for temperatures.



&&

.AVIATION...Low clouds have been persistent from GPI to MSO this
morning. Rain has already developed in Lemhi County north to the
Bitterroot Valley and at KBTM as of 0400MST. Expect further
degradation of ceilings and visibility as rain continues,
especially from Interstate 90 and points south and east. Mountain
obscuration will be a problem from the Bitterroot Mountains
eastwards. As the main moisture plume moves away from the region
tonight, upper clouds will dissipate, but low clouds may not.
Further fog and low cloud issues are expected through Monday
morning.


&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...None.
ID...None.
&&

$$