800
FXUS65 KMSO 151956
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
1256 PM MST Sat Nov 15 2025

.DISCUSSION...

KEY MESSAGES:

-  Periodic light snow across mountain areas and passes Monday
   into Wednesday, with minimal impacts.

-  Split flow pattern into next week, with no significant winter
   weather impacts.

-  Increased odds for atmospheric river and colder winter weather
   by next weekend (November 22-23) into Thanksgiving week.

Global models suggest the Western US will remain under a split
flow weather pattern through the next week, with the core of the
Pacific jet remaining offshore. As Pacific systems approach the
West Coast this coming week, models suggest they will continue to
dig southward into the Great Basin and Southwest. This will leave
the Northern Rockies under a relatively mild west- southwest flow
pattern, with periods of showers as weak atmospheric waves supply
moisture and lift.

The first system arrives Sunday into Monday, with showers
increasing across central Idaho by Sunday morning with snow levels
above 8,000 feet. Shower activity will focus across north-central
Idaho and northwest Montana through Sunday evening. Models suggest
a secondary wave will move into the Yellowstone region, with
showers moving into Lemhi County and southwest Montana, along the
divide. Snow levels will fall near 6,500-7,000 feet, with light
snow accumulations, generally a trace to 2 inches across mountain
areas. This snow will bring only minor impacts, given recent warm
temperatures to pass areas, including Lost Trail and Homestake
Passes.

The next Pacific system will dig into the Great Basin and
Southwest US Tuesday into Wednesday, with the Northern Rockies on
the far northern influence of this trough. Temperatures will cool
near seasonal normals, with snow levels falling near 5,000-6,000
feet Tuesday to 4,000-5,000 feet by Wednesday, with lower snow
levels along the ID/MT border. Snow shower activity will bring
periodic reduced visibility to area passes, with minor
accumulations generally an inch or less each day. Snow will
struggle to accumulate to roadways during the daylight hours with
any minor impacts during overnight periods.

Global ensembles are hinting at a pattern change by next weekend
(November 22-23). The European EPS ensemble in particularly
suggests the Pacific jet will extent inland across the Pacific
Northwest, with a large subset of ensemble members suggesting an
atmospheric river across the Northern Rockies, along with a cold
front and the potential for widespread mountain snow. Currently
around 70% of model clusters suggest this solution, with the
remaining members keeping the jet further north in Canada with
drier and warmer weather in the Northern Rockies.

Looking ahead towards Thanksgiving week, global ensembles are
hedging towards a northwesterly flow pattern, with increased odds
for colder air and winter weather impacts at times across the
Northern Rockies. This period will be monitored closely in the
coming days given high interest in Thanksgiving travel.


&&

.AVIATION...Remnant light showers, occasional mountain obscurations,
and breezy westerly winds will all gradually dissipate this
afternoon. Otherwise, VFR conditions will be common into Sunday.
Patchy fog and/or stratus may occur tonight where partial clearing
occurs including KGPI and KMSO.

An upper low off the southern California coast will lift into the
Great Basin on Sunday sending weak disturbances through the
Northern Rockies into Monday. One of these disturbances will lead
to increasing mid- level clouds on Sunday morning followed by
periodic areas of light/moderate showers. Snow levels will remain
near 7000 feet and above through Monday. Occasional mountain
obscurations may occur on Sunday but more impactful reduced
ceilings generally wait until Sunday night/Monday morning. Winds
will be relatively light Sunday into Monday with the highest gusts
only reaching 15-20 kts and confined to southwest Montana/Lemhi
County each afternoon.



&&

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

$$