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FXUS65 KMSO 222152
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
252 PM MST Tue Jan 22 2019

...Difficult winter driving conditions expected tonight through
Wednesday...

.DISCUSSION...A winter storm is expected to develop this evening
and continue through Wednesday. We feel the hardest hit area in
terms of high impact with moderate to heavy snow, will be along the
Highway 200 and Interstate 90 corridors, especially in Sanders
and Mineral Counties. We have the highest confidence that the
mountains will get at least a foot or more of snowfall.

We have winter weather advisories hoisted for most areas except
for the Riggins area in central Idaho and Lemhi County. Snow will
fall in the valleys of Lemhi County, but it will be light amounts.
Williams Creek Summit could see half a foot of snow spread out in
a 24 hour period. Following shifts will reassess whether Lemhi
County may need an advisory or not. The advisory for the Camas
Prairie, Idaho was a tricky one in that we are expecting strong
southerly winds to develop later today and continue through
Wednesday morning. Usually this means that these downslope winds
will cause temperatures to rise above freezing, but we think the
light to moderate snow may delay the warming until after daybreak.
With that in mind, the snow will initially be more dry and will
blow around especially along portions of Highway 95. This wet
weather will also an issue for any newborn livestock. For more
information on snow amounts and timing see the advisories and
warning by visiting http://www.weather.gov/mso/

The Northern Rockies will be under northwesterly flow for the latter
part of the work week. A subtle disturbance will be moving through
the region Thursday night into Friday morning. This type of
feature in northwesterly flow is conducive of widespread light
snow showers with western Montana receiving the bulk of the
precipitation. The valleys have the potential of picking up an
inch or two of new snow. Moderate confidence in this event as all
models are picking up on the feature, but timing is a little
uncertain at this time.

The region will remain under this northwesterly flow through Sunday,
but warmer air will move into the region. The warming aloft will
allow for the development of valley inversions with the
possibilityof patchy freezing fog throughout the region.

A more robust system is expected to move into the region on Sunday
night into Monday. This feature has the potential bringing colder
air into the region with potential of significant snow across
western Montana.

&&

.AVIATION...Low clouds and snow will blanket the Northern Rockies
air space through at least 24/0000Z. Anticipate widespread terrain
obscurations in snow and low clouds. Light snow will reduce
visibility, ceilings at KGPI and KMSO after 23/0600z and continue
throughout Wednesday. Moderate snow is expected to create the
lowest visibility and ceilings near KGPI and KMSO 23/1000Z through
23/1600Z. Ceilings and visibility will also be reduced due to snow
at KBTM and KSMN, peaking 23/0800Z through 23/1600Z. Northeast
wind gusting over 20 knots is anticipated at KGPI 23/1800Z through
24/0200Z as well.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...Winter Weather Advisory from 8 PM this evening to 5 PM MST
Wednesday Missoula/Bitterroot Valleys.

Winter Storm Warning from 8 PM this evening to 11 AM MST
Wednesday Lower Clark Fork Region.

Winter Weather Advisory from 8 PM this evening to 5 PM MST
Wednesday Flathead/Mission Valleys.

Winter Weather Advisory from 8 PM this evening to 5 PM MST
Wednesday West Glacier Region.

Winter Weather Advisory from 8 PM this evening to 11 AM MST
Wednesday Kootenai/Cabinet Region.

Winter Weather Advisory from 8 PM this evening to 11 PM MST
Wednesday Bitterroot/Sapphire Mountains.

Winter Weather Advisory from 8 PM this evening to 5 PM MST
Wednesday Potomac/Seeley Lake Region.

Winter Weather Advisory from 11 PM this evening to 11 PM MST
Wednesday Butte/Blackfoot Region.

ID...Winter Weather Advisory from 7 PM this evening to 4 PM PST
Wednesday Northern Clearwater Mountains.

Winter Weather Advisory from 7 PM this evening to 4 PM PST
Wednesday Southern Clearwater Mountains.

Winter Weather Advisory from 7 PM this evening to 4 AM PST
Wednesday Orofino/Grangeville Region.

&&

$$
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