Area Forecast Discussion
Issued by NWS Missoula, MT

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FXUS65 KMSO 182145
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
245 PM MST Wed Jan 18 2017

.DISCUSSION...Overall the first round of precipitation is on the
decrease for most areas in central Idaho and western Montana. The
only exception is for parts of Northwest Montana near the Idaho
border and in central Idaho where light rain/freezing rain is
expected to persist through the afternoon. Also due to the recent
cold temperatures, many subsurface temperatures are below freezing
which will cause refreezing in many areas that received
precipitation today as the sun sets this evening.

The next round of precipitation is expected to begin moving into
central Idaho this evening and then spread north into northwest
Montana tonight. For central Idaho, models have trended wetter
with this next round of precipitation and an additional 0.25 to
0.50 inch of rain will be possible overnight tonight for places
surrounding Orofino and Pierce. For northwest Montana, the
greatest precipitation is expected to be along the Montana/Idaho
border and could see anywhere from 0.10 to 0.4 inches of
precipitation. Snow levels is expected to be around 3000 feet so
valleys near this level should expect mixed precipitation.

THURSDAY through SATURDAY the northern Rockies will be under the
influence of a trough. A cooler air mass will settle over the
region and keep temperatures at or slightly below normal. Normal
highs are in the upper 20s and lower 30s. This cooler air mass,
unstable air, and moisture in place under this trough will result
in scattered numerous snow showers Thursday and scattered snow
showers Friday and Saturday.

Our next impactful weather disturbance has slightly slowed, but
still anticipated to begin to impact portions of north-central Idaho
and areas along the MT/ID border by SUNDAY EVENING. This system
has similarities to what we are dealing with this morning
(Wednesday), the difference is, cooler temperatures will be
associated with it compared to today`s. With that being said, if
the current timing remains, most locations above 1500 feet in
north-central Idaho should see light snow. If it were to speed up
any, some rain will mix in at the lowest elevations.

Currently, impacts for western Montana will likely be Monday morning,
during the morning commute. Light snow, with isolated areas of moderate
intensities will be possible beginning after midnight, and continuing
through the late morning hours. As it stands now, areas in the
northern Bitterroot, through Missoula and north into northwestern
Montana have the best chance for seeing these conditions. Major
impacts are not expected at this time. There is still a few days
between then and now, expect further updates to the current
timing.

A northwesterly flow will likely keep light snow showers in the
forecast for most everyone through Tuesday and Wednesday morning.
Little accumulation is expected with these showers. A ridge of
pressure will build over the region Thursday and linger of over
the area through next weekend. So cold pools, (inversions), could
make a return to some valleys.

&&

.AVIATION...Overall, the precipitation has decreased across the
region with mainly light rain/snow possible at area terminals KGPI
and KMSO through this afternoon. Another round of moisture will
begin to move in tonight and some light rain/snow/freezing rain
will be possible again Thursday morning.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...Winter Weather Advisory until 11 AM MST Thursday
     Flathead/Mission Valleys.

     Winter Weather Advisory until 11 AM MST Thursday
     Kootenai/Cabinet Region.

     Winter Weather Advisory until 11 AM MST Thursday Lower Clark
     Fork Region.

ID...Winter Weather Advisory until 10 AM PST Thursday Lower Hells
     Canyon/Salmon River Region.

     Winter Weather Advisory until 10 AM PST Thursday Northern
     Clearwater Mountains...Orofino/Grangeville Region.

     Winter Weather Advisory until 10 AM PST Thursday Southern
     Clearwater Mountains.

&&


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