FXUS65 KMSO 270925
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
325 AM MDT Sun Oct 27 2024

.DISCUSSION...

KEY MESSAGES:

- Strong cold front today will bring breezy winds and a change to
  cooler conditions by Monday.

- Mountain snow tonight through Tuesday, bringing periods of slick
  conditions on mountain passes.

- A colder system expected towards the end of the week, which
  could bring snow to lower elevations.

A strong cold front will move through north central Idaho and western
Montana today, bringing breezy winds and increased chances for
precipitation by this afternoon. Most areas will see wind gusts of
25 to 35 mph, but the strongest winds will be across southwest
Montana into Lemhi County where there is a 50-60 percent chance of
winds gusting to 40 mph or higher. A lake wind advisory has been
issued for Flathead Lake this morning through this evening for
winds causing choppy conditions, which could be dangerous for
small water craft. In addition, warm, dry and breezy conditions
across southwest Montana will lead to near critical fire weather
conditions, especially with frontal passage this afternoon.

Along and behind the front, precipitation is expected to develop
this afternoon into the overnight hours. At the same time, snow
levels will be gradually lowering to around 4500 to 5000 feet by
Monday morning. Forecast models continue to focus the heaviest
precipitation through north central Idaho and along the
Continental Divide in northwest Montana. One to three inches of
slushy wet snow is expected by mid day Monday for the higher
elevation mountain passes, including Lost Trail, Lookout, Lolo
and Marias. The higher elevations of the Bitterroot/Sapphire and
Clearwater Mountains could see as much as 3 to 5 inches new
accumulation.

Monday will be significantly cooler, by as much as 15 to 20
degrees, with lingering shower activity, especially over the
higher terrain. Slushy snow will continue for the higher
elevations into Tuesday. Periods of slick travel are possible over
the mountain passes mentioned above, especially in the
overnight/early morning hours. Mild ground conditions should keep
impacts to roads fairly short lived for the most part.

A transitory ridge of high pressure will slide over the region on
Wednesday causing a respite in the shower activity. However, with
recent precipitation, fog and low stratus may develop Wednesday
morning. Another system will settle over the Northern Rockies for
the latter part of the work week. This trough of low pressure
appears to be even colder, allowing for the potential for the
majority of the valleys of western Montana and Lemhi county to
experience their first snow of the season. Any accumulation in
the valleys will be very light and short-lived. The probability
for a more significant snow event for the higher terrain has
increased in recent model runs. The probability for 4 inches or
greater of snow is around 80 percent for Lookout Pass, 60 percent
at both Lolo Pass, and Lost Trail Pass, and 50 percent for Marias
Pass.


&&

.AVIATION...A cold front will move through north central Idaho and
northwest/west-central Montana this morning, then through
southwest Montana this afternoon. Breezy south to southwest winds
are anticipated with the front, with gusts 30 to 35 kts
anticipated. The strongest winds are expected near the Continental
Divide into southwest Montana, including for KBTM. Low level wind
shear may be observed this morning before the atmosphere becomes
more fully mid by mid day. With and behind the front,
precipitation will develop with lowering ceilings obscuring the
higher terrain. Snow levels will drop, allowing for snow fall down
to around 4500 to 5000 feet by Monday morning.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...Lake Wind Advisory from 9 AM this morning to 8 PM MDT this
     evening for Flathead/Mission Valleys.

ID...None.
&&

$$