Area Forecast Discussion
Issued by NWS Missoula, MT

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FXUS65 KMSO 242141

Area Forecast Discussion
National Weather Service Missoula MT
241 PM MST Fri Feb 24 2017

.DISCUSSION...This weekend the majority of the western U.S. down
to California will be under the influence of a large scale trough
pattern. Smaller weather disturbances in this trough will move
into the Northern Rockies from British Columbia. Temperatures will
continue to be about ten degrees below normal with high temperatures
struggling to reach the freezing mark. These colder temps combined
with the unstable moist air will produce scattered snow showers
Saturday. Sunday a little more organized and wet system will bring
widespread snow to the region with accumulating snows (2-6") over
Lolo, Lookout, Lost Trail and Marias passes to make travel
difficult at time. Valley locations may also be impacted by a few
inches of snow.

This general troughiness pattern over the western U.S. will
continue through the middle of the week. As another disturbance
moves through the Northern Rockies on Monday afternoon and
evening. The primary focus of the precipitation will be across
north central Idaho into west central Montana. The mountain passes
along the Montana/Idaho border could receive several inches of new
snow from this feature.

The models are indicating the flow will become westerly by the
middle of the week bringing breezy conditions across the region.
Confidence is low, but this flow pattern has the potential of
tapping into a subtropical moisture plume which would bring a
significant amount of snow to the mountains of north central Idaho
and northwest Montana.


.AVIATION...Scattered snow showers will continue across the
Northern Rockies this afternoon and evening. The shower activity
is anticipated to diminish after sunset this evening. Then a weak
feature will drop out of Canada tonight which could keep showers
lingering across northwest Montana. All terminals have the
potential of being impacted by showers this afternoon and evening.
But KGPI has the best potential of showers lingering through the
overnight hours.



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