Area Forecast Discussion
Issued by NWS Missoula, MT

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FXUS65 KMSO 221039

Area Forecast Discussion
National Weather Service Missoula MT
339 AM MST Sun Jan 22 2017

A series of snow showers tracking through the Northern Rockies
overnight/early this morning have already produced light snow
accumulations and some slick roads. The next substantial wave of
snowfall will begin this afternoon for north-central Idaho and
move into west-central and northwest Montana by tonight into
Monday. Snow levels will fluctuate between 1500-2500 feet during
the Sunday night period. A few inches of snow accumulation is
possible for mountain passes such as Gilmore Summit, Lookout,
Lolo, Lost Trail, and Marias Passes. By Monday, the overall flow
will turn northerly, and showers will drift from northwest Montana
back into west-central Montana and north-central Idaho for
another round of light snow accumulations. These showers could
lead to slick conditions for the mountain passes along the
Continental Divide and Lemhi County. Many roads already have black
ice in place from refreeze, and therefore any snowfall on top of
black ice (especially on bridges and overpasses) could further
reduce vehicle traction.

The northerly flow will persist through at least Thursday,
keeping scattered snow showers throughout the Northern Rockies.
Each day the probability of snow diminishes. Temperatures will be
trending cooler than average for this time of year. The models are
still indicating a ridge of high pressure moving over the region.
This ridge will cause for drier conditions with the development
of valley inversions.


Snow showers are tracking through KMSO, KGPI, and KBTM early this
morning, which can briefly reduce visibility and lower cloud
ceilings. Patchy dense freezing fog and visibility reductions will
remain in the vicinity of the terminals through morning hours.

The next wave of snowfall will begin after 22/2100Z for
KSMN and after 23/0000Z for KMSO, KBTM, and KGPI. Snow will reduce
ceilings and visibility for all terminals by tonight, though snow
accumulations at the TAF sites will generally amount to a trace
up to 3 inches through Monday morning.


MT... Winter Weather Advisory from 5 PM this afternoon to 11 AM MST
    Monday Flathead/Mission Valleys...Kootenai/Cabinet Region...
    Lower Clark Fork Region...West Glacier Region.

ID...Winter Weather Advisory from 1 PM this afternoon to 4 AM PST
     Monday ABOVE 2500 FEET for the Northern Clearwater
     Mountains...Southern Clearwater Mountains.


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