Area Forecast Discussion
Issued by NWS Missoula, MT

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FXUS65 KMSO 271050
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
350 AM MST Mon Feb 27 2017

.DISCUSSION...A weak, semi-stationary front has parked over
Missoula where it has been snowing off and on all night. Other
areas in Western Montana have been receiving snow showers tonight
too, but much weaker and less frequent. Meanwhile in Central Idaho
an approaching low is being absorbed back into the jet stream.

So today Central Idaho will see some significant snow, as will
western Montana as these two features rejoin together. The impacts
will mainly be for the morning commute where snow and ice have
accumulated on untreated roads. As the day goes on, the sun will
do its work warming the pavement causing the snow to stop
accumulating on most roads in Central Idaho. Conditions will
improve today over most of Western Montana too as the colder air
mass, causing most of this snow, retreats back to the east.

Tuesday the area remains in northwest flow with another shortwave
disturbance causing accumulating snow. As drier air aloft moves in
behind this system Tuesday afternoon, it is likely that snow
showers will start to organize into bands causing highly variable
conditions. If this continues after sunset, the roads will get
cold enough to accumulate snow again causing rapidly changing road
conditions.

Wednesday: No big changes to the forecast. It still looks like a
windy day across the region with snow showers abounding. Strong
crosswinds from Avon to Deer Lodge to I-15 near Butte will be
possible. Wind gusts in those regions will exceed 40 mph at times.
Snow showers will bring visibility reductions and strong gusty
winds. There is also a small threat for intense snow bands to
develop which could last into Wednesday night, but confidence is
low at this time.

Thursday and Friday: A cold upper level trough will track
eastward into northern British Columbia while its associated low
will move into Alberta. On the southern side of this trough, the
combination of jet energy and high levels of moisture will bring
heavy precipitation to the Pacific Northwest. Left-overs of this
moisture will reach the Northern Rockies Thursday night into
Friday bringing higher snow levels and decent mountain snowfall.
There is the potential for some valley snow across northwest
Montana, but strong downsloping effects will limit intensities and
amounts. Another impact will be strong winds and crosswinds affecting
areas along the Continental Divide and southwest Montana.

Next weekend: A frontal boundary stalls from Central Idaho into
west-central Montana and will continue to bring moderate to heavy
precipitation along this feature. A cold front will move through
sometime into Sunday which could bring a combination of wintry
impacts and strong winds.


&&

.AVIATION...Unstable northwest flow today with a moist air mass
overhead will keep the snow showers going through the day, even as
a shortwave exits the region. Terminals KGPI and especially KMSO
will be most affected. Mountain obscurations will be wide spread
across the region today.


&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...Winter Weather Advisory until noon MST today Bitterroot/Sapphire
     Mountains.

     Winter Weather Advisory until noon MST today Missoula/Bitterroot
     Valleys.

     Winter Weather Advisory until noon MST today Butte/Blackfoot
     Region...Potomac/Seeley Lake Region.

     Winter Weather Advisory until noon MST today Lower Clark Fork
     Region.

ID...Winter Weather Advisory until 11 AM PST this morning Lower Hells
     Canyon/Salmon River Region...Orofino/Grangeville Region.

     Winter Weather Advisory until 11 AM PST this morning Southern
     Clearwater Mountains.

     Winter Weather Advisory until 11 AM PST this morning Northern
     Clearwater Mountains.

&&

$$


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