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000
FXUS65 KMSO 261019
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
319 AM MST Fri Feb 26 2021

.DISCUSSION...Regional radar and satellite analysis depict the
next surge of Pacific moisture has moved onshore into western
Oregon and Washington early this morning. Widespread snowfall is
expected by the morning commute across north central Idaho as this
surge of moisture moves across eastern Washington. High
confidence exists for a period of heavy snowfall across the
Clearwater Mountains this morning through the late afternoon
hours, where a winter storm warning remains in effect. Forecast
soundings and cross- sections depict a favorable scenario for
snowfall rates exceeding one inch per hour, particularly across
mountain locales in Idaho County.

A shortwave trough and associated surface cold front will push
across western Montana by the early afternoon. Modest confidence
exists for a period of accumulating snowfall across the Camas
Prairie Friday afternoon as the upper level flow becomes
northwesterly. High resolution model guidance continues to
advertise the potential for intense snow showers along and south
of the I-90 corridor in western Montana this afternoon and early
evening. Given relatively warm surface temperatures and a late
February sun angle, road impacts will be highly variable.
Nonetheless, the afternoon commute will likely be impacted by
these snow showers. Model guidance has trended higher on snowfall
accumulations this afternoon and early evening across the Missoula
and Bitterroot valleys, suggesting a 50/50 chance for 2 inches or
more of snowfall by late this evening. Further winter weather
highlights may be warranted for the Bitterroot and Missoula valley
as these showers begin to come together. Snow shower activity
will gradually retreat to the higher terrain Friday night into
Saturday morning.

A relatively unstable northwesterly flow will promote snow shower
activity Saturday across the Northern Rockies. Periodic
visibility reductions will be the primary impact to valley
locations, with little to any accumulation expected. The
Clearwater, Bitterroot, and Mission mountains will continue to see
accumulating snow, albeit, light amounts.

A drying and warming is expected Sunday and Monday as high
pressure builds across the Northern Rockies. Model guidance
continues to struggle with the evolution of the weather pattern
Tuesday through Thursday this upcoming week. Guidance does agree
with a splitting upper trough approaching the Pacific Northwest
coastline Monday. Model solutions quickly diverge as this system
approaches the Northern Rockies. The bottom line is temperatures
will remain near seasonal averages with highs in the upper 30s to
low 40s across valley locations. Periods of light to moderate
mountain snowfall are possible during this period, particularly
along the Idaho and Montana border. /Lukinbeal


&&

.AVIATION...High confidence exists for widespread snowfall
across north central Idaho through 27/0000Z as a Pacific storm
system moves into the area. Periodic reductions in visibility will
continue across west central Montana this morning as snow showers
traverse across the Clearwater and Bitterroot Mountains.
Convective snow showers and bands will develop for areas along and
south of the I-90 corridor in western Montana this afternoon.
Sudden visibility reductions will be common as snow showers will
be capable of producing snowfall rates of up to one inch per hour.
Brief IFR to LIFR visibility reductions are possible at KMSO from
26/1800z to 27/0300z. Snow shower activity will gradually
diminish following 27/0600z, with the majority of accumulating
snow being confined the higher terrain. /Lukinbeal


&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...     Winter Weather Advisory until 8 AM MST this morning West Glacier
     Region.

     Winter Weather Advisory until 8 AM MST this morning
     Kootenai/Cabinet Region.

     Winter Weather Advisory until 5 PM MST this afternoon
     Bitterroot/Sapphire Mountains.

     Winter Weather Advisory until 5 PM MST this afternoon
     Potomac/Seeley Lake Region.

     Winter Weather Advisory until 5 PM MST this afternoon Lower
     Clark Fork Region.

ID...Winter Weather Advisory until 4 PM PST this afternoon Lower
     Hells Canyon/Salmon River Region.

     Winter Storm Warning until 4 PM PST this afternoon Northern
     Clearwater Mountains.

     Winter Storm Warning until 4 PM PST this afternoon Southern
     Clearwater Mountains.

     Winter Weather Advisory until 4 PM PST this afternoon
     Orofino/Grangeville Region.

&&

$$