Area Forecast Discussion
Issued by NWS Missoula, MT

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FXUS65 KMSO 232139
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
239 PM MST Mon Jan 23 2017

.DISCUSSION...Scattered light snow showers will persist, at least
in the mountains of western Montana through the evening hours. The
valleys should only see a few flurries, if that. Patchy fog may
also re-develop in the morning for the valleys of western Montana,
but not expected it to be as widespread and dense as this
morning.

The flow pattern over the Northern Rockies will transition to a
more northwesterly flow overnight tonight. During the day
tomorrow, a shortwave trough will slide south through the flow,
that will help promote widespread light snow showers for the
mountains and valleys south and west of the I-90 corridor. These
types of scenarios typically produce light accumulations of a
trace to 2 inches. But will not be surprised if someone receives
3 to 4 inches, but that will be fairly isolated. Areas north of
I-90, will still see light snow, but perhaps not as much as the
locations mentioned above. The one exception, will be the south
end of Flathead Lake, and highway 35 along the east side. These
showers, combined with the northerly flow could be enhanced by the
lake. A few inches of snow is possible there.

Snow shower activity will continue on Wednesday and Thursday but
the overall flow will be weak, thus limiting the potential for
organized snow bands. Accumulations will remain light but may be
enough to bring changeable, slippery roads at times.

Confidence continues to grow for a transition to strengthening
valley cold pools beginning Friday through the coming weekend as
a ridge of high pressure builds overhead. The setup is not ideal
for strong inversions, as high and mid level cloud cover will
occasionally pass through but we will likely see deteriorating air
quality and the possibility of persistent fog and/or stratus.
Forecast models hint at a quick moving disturbance producing a
round of snow late Sunday into Monday but confidence is low.


&&

.AVIATION...Mountain snow showers and areas of low stratus will
continue to obscure mountain tops through the overnight hours for
all aviation sites of western Montana and north-central Idaho. The
valleys are not expected to see any impacts due to snow during
this time. Tomorrow, widespread light snow showers will develop
across the Northern Rockies, with west-central Montana and north-
central Idaho having the best chances for seeing snow
accumulations. Snow should begin to fall for most regions by
sunrise, with the more impacting snow being at KMSO around
25/0000Z.



&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...None.
ID...None.
&&

$$



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