FXUS65 KMSO 111247
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
547 AM MST Mon Dec 11 2023

.UPDATE...Added a winter weather advisory for the Flathead/Mission
valleys and the Seeley/Swan region. A mix of slushy snow and light
freezing rain will make slick conditions through the morning
commute.


&&


.AVIATION...Areas of fog and low stratus will continue through
this morning, impacting airfields KMSO and KGPI. Fog will
generally improve as a weather system approaches this morning. A
Canadian cold front will begin to cross the Continental Divide
this morning, making it to KGPI around 11/15z and to KMSO around
11/19z. Ahead of the front, a burst of precipitation is expected,
primarily between 11/10z and 11/16z for KGPI and between 11/14z
and 11/20z for KMSO. Precipitation type will be a wintry mix of
slushy snow and light freezing rain as snow levels hover at or
just above the valleys of western Montana. With and behind the
front, winds will transition to northeasterly with gusts of 20 to
25 kts possible, especially through exposed valleys/terrain. KBTM,
KHRF and KSMN may also see brief periods of snow showers, but
will be more scattered in nature. Drier air moves into the region
tonight to end precipitation, but stratus and fog will likely
develop by Tuesday morning.

&&

.PREV DISCUSSION... /ISSUED 213 AM MST Mon Dec 11 2023/

DISCUSSION...A weak cold front is slowly moving south out of
Canada this morning and is expected to cross into northwest
Montana a little before sunrise and then into west-central Montana
by mid morning. A brief burst of precipitation is expected to
accompany the front, particularly across northwest Montana near
the Continental Divide. Snow levels are hovering at or just above
valley bottoms, making precipitation type a tough forecast. Likely
a wintry mix of rain, freezing rain and snow will occur.
Accumulations will be minimal, but conditions could become slick
during the morning commute due to light ice accumulations and
slushy snow. We currently do not have the Flathead/Mission valley
in a winter weather advisory, but this may need to be adjusted as
we see how precipitation develops through the morning. Mountain
showers will continue area wide today, particularly in southwest
Montana and north central Idaho, but additional accumulations will
be minimal.

Drier air moves in behind the front this evening, and should
generally reduce showers across the area. A northerly flow will
then build over western Montana and north central Idaho for Monday
night into Tuesday. Lingering clouds and even some light flurries
will be possible.

By Wednesday, high pressure will migrate over the region. Stable
conditions will likely limit valley heating and the potential for
fog and stratus looks likely, especially considering the recent
snowfall across the region. On Thursday, a weak wave of energy
will temporarily move through the ridge of high pressure, bringing
some showers to northwest Montana. Overall stable conditions with
valley inversions will persist however. High pressure will largely
remain in control into next week.

AVIATION...Areas of fog and low stratus will continue through
this morning, impacting airfields KMSO and KGPI. Fog will
generally improve as a weather system approaches this morning. A
Canadian cold front will begin to cross the Continental Divide
this morning, making it to KGPI around 11/15z and to KMSO around
11/19z. Ahead of the front, a burst of precipitation is expected,
primarily between 11/10z and 11/16z for KGPI and between 11/14z
and 11/20z for KMSO. Precipitation type will be a wintry mix of
slushy snow and light freezing rain as snow levels hover at or
just above the valleys of western Montana. With and behind the
front, winds will transition to northeasterly with gusts of 20 to
25 kts possible, especially through exposed valleys/terrain. KBTM,
KHRF and KSMN may also see brief periods of snow showers, but
will be more scattered in nature. Drier air moves into the region
tonight to end precipitation, but stratus and fog will likely
develop by Tuesday morning.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...Winter Weather Advisory until 11 AM MST this morning for
     Flathead/Mission Valleys...Potomac/Seeley Lake Region...
     West Glacier Region.

ID...None.
&&

$$