Area Forecast Discussion
Issued by NWS Missoula, MT

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FXUS65 KMSO 242046

Area Forecast Discussion
National Weather Service Missoula MT
246 PM MDT Sat Mar 24 2018

.DISCUSSION...A cold front continues to work through western
Montana this afternoon, with showers continuing across much of
western Montana and central Idaho. The heaviest showers are
currently occurring along the Continental Divide, where brief
moderate to heavy snow will lower visibilities and cause some
light snow accumulations. Due to warm road surfaces, accumulations
on roadways will be short lived at best. Behind the cold front,
breezy southwest to west winds will continue into the early
evening, with gusts up to 35 mph possible.

This evening and tonight, a low pressure circulation currently
over eastern Washington will move over northwest Montana. Another
round of snow showers is anticipated. Given that most of the
precipitation will occur in the evening, when road surfaces are
still quite warm, impacts are expected to be minimal. However,
areas near the Continental Divide, including through Glacier
National Park may see snow linger into the early morning hours,
which could favor a bit more in the way of accumulations.

Sunday into Monday will see continued cool and showery conditions
with brief breaks with some sunshine. In fact, this pretty
typical, Spring weather will continue through much of next week as
northwest flow aloft remains steadily fixed in place.

By Easter weekend there are some notable model differences that
come into play between the GFS, Canadian and ECMWF models. These
models do, however, agree that a large area of low pressure will
develop somewhere between central Canada and Hudson Bay. And also
that this type of pattern would open the door for dramatically
colder air to plunge southward into Eastern Montana and the
Northern Plains. But where these models disagree is what occurs
over the Pacific Northwest and how that in turn affects the
westward advance of this unseasonably cold air. The 06z & 12z GFS
has been trending towards a stronger area of low pressure digging
south from British Columbia into the Pacific Northwest and thus
also support an artic-like cold front moving into the Northern
Rockies. This was supported by the 00z Canadian model, but not so
much the 12z which aligns with the 12z ECMWF model run.

Suffice it to say, it`s still too soon to place much faith in the
extreme GFS solution at this time. However those planning travel
east of the Continental Divide would want to be ready for winter-
like conditions and dramatically colder temperatures while those
living or traveling west of the Divide will likely need to hold a
few days for better model agreement.


.AVIATION...Widespread showers will linger across much of western
Montana and central Idaho through this evening, which will obscure
the higher terrain at times. Breezy southwest to west winds will
continue, with gusts to 30kts possible into the early evening. Clearing
is expected to occur for west central Montana and portions of
north central Idaho late this evening. However, another round of
snow showers will move into northwest Montana, continuing to
obscure the higher terrain and bringing brief periods of lowered
visibility. Sunday morning will likely see some breaks in the
clouds before the afternoon becomes showery across the region once



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