Area Forecast Discussion
Issued by NWS Missoula, MT

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FXUS65 KMSO 292130

Area Forecast Discussion
National Weather Service Missoula MT
230 PM MST THU JAN 29 2015

.DISCUSSION...Patchy fog and low stratus across the region will
continue under the influence of high pressure bringing stable
conditions and valley inversions through Saturday morning. Like
today, some of the fog will lift to a low stratus, especially the
lower valleys of far northwest Montana, the Mission Valley, and in
the vicinity of Salmon.

A transition to a more active pattern will begin Saturday. The
ridge retrogrades to the west allowing a northwest flow and a
weather disturbance to move through Northwest Montana, especially
along the Continental Divide. Light snow amounts are expected in
the mountains near Glacier NP.

Sunday evening into Monday morning a more significant plume of
moisture will raise chances for valleys to see brief snow which
should quickly transition to light rain. Despite snow levels
rising, all mountain passes should stick with continuous light
snow accumulation through Monday evening.

Monday night through early Wednesday confidence is increasing for
another shot of widespread precipitation. Models are coming into
agreement in spilling arctic air over the Divide into northwest
Montana along with this stronger weather disturbance from British
Columbia. This bears watching; if everything lines up, a decent
boundary will develop and potentially bring widespread
accumulating snows down to the valley floors in Northwest Montana.
It looks now that precip should be in the form of all rain from
about Missoula southward. Again confidence is high for
precipitation and low for type and amount of precipitation. A lot
depends on how much arctic air spills over the divide which is
uncertain now.

Mid to late next week general ridging will return to the Northern
Rockies bringing warmer temperatures above valley inversions that



Patchy Fog is expected to redevelop again after 30/0800z at KGPI,
KMSO and KSMN and lift after 30/1700z. Locally dense fog with
visibility less than 1/4 mile is likely. It`s likely KSMN with strong
inversions will keep low stratus over them throughout the day



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