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000
FXUS65 KMSO 192225
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
325 PM MST Sat Jan 19 2019

.DISCUSSION...Light to moderate snow will impact the Northern
Rockies later this evening through Monday morning. Expect
widespread accumulating snows, especially across the Northwest
Montana valleys where 2-5 inches are expected.

This weather system will impact regions from south to north over a
24-36 hour period. First off, Lemhi county and parts of southwest
Montana can expect snow to begin later this evening. Snow levels
around 5000-5500 feet will limit impacts mainly to Lost Trail
Pass and Georgetown Lake.

This system will gradually move northward overnight impacting much
of North Central Idaho. It`s expected by sunrise snow will begin
to impact Lolo Pass. Snow levels do lower but it gets tricky as we
address the valley floors. Right now it appears it will be warm
enough Sunday morning through the afternoon for all rain or a mix
of rain and snow through much of the Bitterroot valley and
possibly into the Missoula valley. Though snow levels will be low
enough to where the BENCHES AND FOOTHILLS will remain all snow.
Areas that remain all snow can expect several inches of snow.
Precipitation will become all snow by late afternoon through the
evening in the vicinity of Missoula where accumulations of 1-4"
are possible.

NORTHWEST MONTANA now looks to be the focus for the highest
widespread accumulations starting Sunday afternoon through
evening (widespread 2-5"). It`s quite possible some stronger bands
could bring local snow amounts up to 8" of snow. If this occurs
it will be in a narrow area. Travel is also expected to become
difficult along the I-90 corridor from Missoula to Drummond and
Highway 83 in the Seeley Swan and along US 93 from Kalispell to
St. Ignatius.

Scattered snow showers are expected Monday afternoon under a weak
northwest flow pattern. Clearing skies Monday night will make for
a chilly start to Tuesday.

The northwest flow pattern will continue Wednesday where a strong
weather disturbance will move in from British Columbia. This storm
looks favorable for widespread accumulating snows (2-4") across
the valleys and mountains.

A ridge of high pressure will remain to our west through next
weekend. This will allow for an active pattern from a northwest
flow pattern to continue over the Northern Rockies.


&&

.AVIATION...Instability showers will continue into this evening,
mostly on the terrain. Light southerly flow favors stratus
development at KGPI tonight with some reductions in visibility as
well. A general area of light to moderate snow will come together
across southern Idaho County eastward into Southwest Montana early
Sunday morning and shift northward through the day. This will lead
to a period of IFR conditions at KSMN and KBTM through early
Sunday morning with IFR and LIFR conditions at KMSO Sunday morning
and afternoon. Snow is expected to impact ceilings and
visibilities at KGPI by mid afternoon on Sunday. Snowfall may
become heavy for a time on Sunday afternoon especially along or
just north of the I-90 corridor with rates up to an inch per hour
briefly.


&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...Winter Weather Advisory from 11 PM this evening to 8 AM MST
     Monday Butte/Blackfoot Region.

     Winter Weather Advisory from 5 AM Sunday to 8 AM MST Monday
     Bitterroot/Sapphire Mountains...Flathead/Mission Valleys...
     Kootenai/Cabinet Region...Lower Clark Fork Region...
     Missoula/Bitterroot Valleys...Potomac/Seeley Lake Region...
     West Glacier Region.

ID...Winter Weather Advisory from 11 PM this evening to 8 AM MST
     Monday Eastern Lemhi County...Western Lemhi County.

     Winter Weather Advisory from 4 AM Sunday to 7 AM PST Monday
     Northern Clearwater Mountains...Southern Clearwater
     Mountains.

&&

$$