Area Forecast Discussion
Issued by NWS Missoula, MT

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FXUS65 KMSO 192144

Area Forecast Discussion
National Weather Service Missoula MT
244 PM MST Fri Jan 19 2018

.DISCUSSION...Low amplitude trough is currently residing over the
Northern Rockies. One weak disturbance moved through the region
last night through this morning which brought a mixture of rain
and snow to the region. Now the area is experiencing a momentary
reprieve as another subtle feature brings another round of
precipitation especially to northwest Montana later tonight into
Saturday morning. This feature appears to be significantly weaker
than the past one, so impacts to the region will be minimal.
Clearwater county up into northwest Montana could experience an 1
or 2 of new snow by lunch time on Saturday.

Partial clearing during the evening could allow temperatures to
drop quickly and cause fog to develop. At this moment, fog appears
to be fairly patchy particularly affect north central Idaho into
west central Montana on Saturday morning.

After some low clouds and patchy fog Sunday morning, a seasonably
pleasant afternoon is anticipated. Widespread light snow is
expected to return on Sunday evening with a quick moving
disturbance. An inch or two of snow accumulation is likely for
valley locations, while mountain passes see 3-6 inches with the
higher amounts along the Idaho/Montana border. Travelers should be
prepared for a period of snow packed and slippery roads including
valley locales. Snow will turn showery once again Monday
afternoon into Tuesday and become focused on the terrain.

A continued active weather pattern is anticipated across the
Northern Rockies Tuesday through Friday night, with the highest
impact potential Wednesday through Thursday. In the Wednesday-
Thursday scenario, a cold front will be main feature to produce
quick snow accumulations (mainly trace to 3 inches) at low
elevations, with the high terrain experiencing a long period of
modest snowfall (mainly 6 to 12 inches). Otherwise, low
accumulation snow showers are anticipated throughout much of next
week. Fog and freezing fog may redevelop in the wake of the mid-
week system, however a great deal of uncertainty exists after
Thursday. Temperatures will be slightly cooler than seasonal
averages next week, however nothing too dramatic.


.AVIATION...A few showers will be lingering across the Northern
Rockies this afternoon, then decrease after sunset. A subtle
disturbance makes its way through the region later tonight into
Saturday morning causing an increase in precipitation, especially
across northwest Montana. KGPI could be impacted by the snow by
Saturday morning. Another area of concern will be the development
of patchy fog across north central Idaho into west central
Montana. The winds have be minimal this afternoon around KMSO and
KSMN so these terminals have the best chance of experiencing fog
after 20/09z.



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