967
FXUS65 KMSO 082007
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
107 PM MST Wed Jan 8 2025

.DISCUSSION...

KEY MESSAGES:

- Scattered light snow showers for western Montana through this
  evening.

- Widespread moderate mountain snowfall this weekend, with periodic
  light valley snow impacts.

Scattered light to moderate snow showers will linger over the
Northern Rockies through this evening, with locations along and
east of Highway 93 having a higher likelihood to see light
accumulations.

High pressure will begin building over the region late tonight,
and remain in place through much of Friday. Partial clearing
overnight tonight and tomorrow night, will increase the potential
for patchy areas of dense fog each morning. Those that don`t
experience the fog, will likely be socked in with low stratus.

The next winter impact period will be this weekend. A shortwave
trough of low pressure will move in from the northwest Friday
afternoon, initially bringing the mountains and mountain passes
light to moderate snow. Increasing winds at ridge tops and above
will shadow out most valleys until the western edge of the trough
moves to the east after sunset Friday evening. A light
northwesterly flow Saturday and Sunday will be the period where
the valleys of western Montana will see their best potential for
minor to moderate impacts due to snow. The valleys of north-
central Idaho will likely be too warm to see accumulating
snowfall, aside from Grangeville.

48hr snowfall accumulations Friday afternoon through Sunday
afternoon, will range from 3 to 6 inches at the passes and the
mountains above 5000 feet 6 to 12 inches (Particularly the
Mission and Swan Ranges). The foothills and valleys east and south
of Bigfork in the northern Swan Valley have a 25 percent chance
for seeing 6+ inches. All other valley locations in western
Montana and Grangeville in north-central Idaho will have a 50 to
60 percent probability of seeing 1 to 2 inches during the same
period.

Another weak ridging pattern will setup over the Northern Rockies
by mid-week next week, with increasing probabilities for the
return of fog and stratus.

Long Range Forecast: An increasing number of ensemble members
(30% to 40%) are beginning to hint at a potential cold outbreak
with arctic air sliding south out of Canada around the 18th. Stay
tuned for further details and likelihood of occurrence.

&&

.AVIATION... Light snow is shifting east and diminishing through
the day into late evening. Expect mountain obscurations due to
widespread lowered ceilings into Thursday morning. High pressure
redevelops this evening and fog and low stratus is expected to
return.


&&

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

$$