048
FXUS65 KMSO 222034
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
134 PM MST Fri Nov 22 2024

.DISCUSSION...

KEY MESSAGES:

-  Mixed precipitation in northwest Montana, valley rain and
   mountain snow elsewhere through Friday night.

-  Falling snow levels on Saturday creating winter driving
   conditions.


Surface observations continue to show enough cool air in parts of
northwest Montana to sustain snowfall despite the arrival of
warmer air. Near the Continental Divide, cold air has pushed west
over Marias Pass through Essex, becoming shallow toward West
Glacier. The depth and strength of this cold air remain uncertain,
with model guidance suggesting a wide range of temperature
scenarios from Kalispell north and east through Saturday morning.

Snowfall is expanding across much of Lincoln and Flathead
counties. However, with warmer air moving in aloft and uncertainty
about the depth of the cold air, there is a 20-40% chance of
freezing rain by noon Saturday. This wintry mix has prompted the
issuance of winter weather advisories. For Kalispell and the
Flathead Valley, rain is expected to persist until Saturday
afternoon, so an advisory has not been issued at this time.
Elsewhere, with high snow levels expected, no additional winter
weather advisories are anticipated.

Snow levels are expected to lower on Saturday, particularly in
the afternoon, following the passage of a cold front from the
west. Precipitation will likely become more scattered and showery
behind the front.

A shortwave trough passing Saturday night will bring another
chance for snow, with the primary focus shifting to north-central
Idaho, Lemhi County, and southwest Montana.

Looking ahead to next week, cooler and showery conditions are
expected. However, no significant weather systems currently stand
out.

&&

.AVIATION...Moisture from an atmospheric river will continue to
provide periods of precipitation (mostly rain for valleys).
Lowered ceilings and visibility reductions will be common with fog
development potential between precipitation episodes. There is
decent consensus on a brief break in widespread precipitation this
evening followed by another extended period of rain by early
Saturday at KGPI, KMSO and KHRF. Scattered showers will impact KBTM
and KSMN rather than the persistent rainfall. One wild card
overnight/early Saturday, there is a 20-30% probability of
shallow cold air from the east, turning rain over to snow or
light freezing rain at KGPI.



&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...Winter Weather Advisory until noon MST Saturday for
     Kootenai/Cabinet Region.

     Winter Weather Advisory until 5 PM MST Saturday for West Glacier
     Region.

ID...None.
&&

$$