466
FXUS65 KMSO 050930
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
230 AM MST Wed Feb 5 2025

.DISCUSSION...

KEY MESSAGES:

-  Periods of moderate to heavy snow continue from central Idaho
   into west-central Montana this morning

-  Another round of widespread snow on Friday, focused mainly
   south of I-90



 Winter Storm Update

The ongoing winter storm, which has already produced impressive
snowfall totals of up to 24 inches as of Tuesday evening,
continues today. Water vapor satellite imagery shows moisture
streaming into the region in a southwesterly flow aloft.
Meanwhile, a surface low-pressure system in south-central Idaho is
expected to track eastward through Lemhi County toward
Yellowstone by 11 AM. This setup favors heavy snowfall north and
west of the low`s path, intensifying winter storm impacts this
morning.

A well-defined cold front advancing from the west is on course to
move through north-central Idaho and western Montana today,
shifting upper-level winds to a westerly direction. Forecast
soundings indicate sufficient cooling in the warm nose, currently
above 7,000-8,000 feet, which will help mix out the Arctic air
mass across much of western Montana. This will also bring westerly
winds, even to the valleys.

 Additional Snow Tonight

Another round of snow is expected tonight as moisture increases,
with high-resolution models suggesting the formation of snow bands
in a descending dry layer under unidirectional westerly flow.
This could result in enhanced snowfall swaths through at least
Thursday morning.

 More Snow on Friday?

Most numerical weather models agree on another snow event from
Friday into Friday night. A low-pressure system is forecasted to
track through the region, concentrating snowfall along and south
of the I-90 and Highway 12 corridors. The combination of moisture
and a reinforcing push of Arctic air will create favorable
conditions for valley snow.

Snowfall totals will depend on the low`s exact path. A less
favorable track could result in 1-3 inches, while a more optimal
track could bring 4-8 inches.

Stay tuned for further updates as the storm evolves.

&&

.AVIATION...Snow is concentrated north of a surface low-pressure
system moving through the southern portion of the forecast area.
Periods of moderate to heavy snowfall will shift from west to east
this morning, leading to widespread impacts, including low
ceilings and reduced visibility at all TAF sites.

By this afternoon, a cold front is set to move through the
Northern Rockies, shifting winds to a westerly direction and
causing snowfall to become more showery. Model cross-sections
indicate sufficient moisture for continued terrain obscuration.

Another round of snow is expected tonight.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...Winter Storm Warning until 11 AM MST this morning for
     Bitterroot/Sapphire Mountains...Butte/Blackfoot Region...
     Lower Clark Fork Region...Missoula/Bitterroot Valleys.

     Winter Storm Warning until 8 AM MST this morning for
     Kootenai/Cabinet Region...West Glacier Region.

     Winter Storm Warning until 9 AM MST this morning for
     Flathead/Mission Valleys...Potomac/Seeley Lake Region.

ID...Winter Storm Warning until 10 AM PST this morning for Lower
     Hells Canyon/Salmon River Region...Northern Clearwater
     Mountains...Orofino/Grangeville Region...Southern
     Clearwater Mountains.

     Winter Weather Advisory until 11 AM MST this morning for Eastern
     Lemhi County...Western Lemhi County.

&&

$$