Polson, Montana 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

121
FXUS65 KMSO 142058
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
158 PM MST Thu Nov 14 2024

.DISCUSSION...

KEY MESSAGES:

-  Light snow Friday into Saturday for north-central Idaho into
   southwest Montana.

-  Strong cold front Sunday into Monday bring hefty snow and gusty
   winds to the higher terrain and potential for snow in the
   valleys.

-  Ridge of high pressure building over the region towards the
   latter part of next week.

Lingering showers will move through the Northern Rockies this
afternoon into the evening. The coverage and intensity of these
showers will diminish after sunset. A weak ridge of high pressure
slides through the region later tonight into Friday morning which
will allow for the development of patchy fog and low stratus. The
fog/stratus should dissipate by late Friday morning.

A mid-level circulation is still expected to move across
southeast Idaho into central Montana late Friday into Saturday.
The path of this disturbance will bring light snow to north
central Idaho and southwest Montana. Lolo, Lost Trail, Bannock,
Homestake and MacDonald passes should anticipate 1 to 2 inches of
snow by Saturday morning. The models are still showing a 25
percent chance that the path of this disturbance could shift to
the west, which would increase snow accumulations at the
aforementioned passes.

The upper level flow will become southwesterly on Saturday
allowing for ample moisture to begin to stream into northwest
Montana. This moisture plume will shift to the east Saturday night
into Sunday causing widespread mountain snow and a wintry mix in
the valleys. A strong cold front is expected to push through the
region Sunday night. This front will cause snow levels to drop to
around 2500 feet by Monday morning. The majority of the Northern
Rockies valleys could experience snowfall by Monday morning, but
accumulations should be relatively light.

Also gusty southwesterly winds are expected to develop ahead of
the front on Sunday and then turn to the west after the frontal
passage. Widespread wind gusts of 20 to 30 mph are expected in the
valleys with the higher terrain having gusts into the 40 mph
range. The combination of wind and snow could create difficult
driving conditions over mountain passes Sunday into Monday
morning. The pass that will have the highest chance for blowing
snow and reduced visibility is Marias Pass Sunday night through
Monday.

Showery conditions will persist through Monday into Tuesday as
snow levels remain around 2500 feet, so the potential exists that
the valleys could have additional snow accumulation.

Around 90% of the models are still showing a strong ridge of high
pressure building over the western United States by the latter
part of the work week. A ridge would cause stable conditions
allowing for the development of fog and low stratus. Another
concern would be the degradation of air quality in the valleys.

For more information about the forecast, a YouTube briefing was
recorded today. https://youtu.be/s3dwffaYKu8

&&

.AVIATION...Gusty westerly winds and scattered showers will
continue to impact the Northern Rockies this afternoon into the
evening. Both wind and showers will diminish after sunset this
evening. A subtle ridge of high pressure moves across the late
tonight into Friday. This ridge will allow for the development of
patchy fog and low stratus which could impact KGPI and KMSO by
15/12z. The fog and stratus should diminish after 15/16z Friday
morning.


&&

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

$$