Polson, Montana 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

131
FXUS65 KMSO 231004
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
304 AM MST Sat Nov 23 2024

.DISCUSSION...

KEY MESSAGES:

- An atmospheric river continues to stream moisture into the
  region this morning, causing moderate to heavy precipitation in
  the mountains.

- Cooler air arrives today, causing snow levels to drop down to
  the valleys just as the precipitation is decreasing.

The upper level trough to the northwest of the region will start
to split apart today. It has been supporting an atmospheric river
over the region for the last few days, and that will start to
break apart this evening. As it does, mildly cooler air will cause
the snow levels to drop down to the valleys just as the
precipitation is decreasing. As a result, many valleys of western
Montana could see some snow Sunday morning, with the larger
valleys expected to pick up less than an inch of snow. Along the
Continental Divide, arctic air will continue to seep through, but
won`t get any mid or upper level support to come across the divide
as those winds will remain westerly. So any impacts from that are
expected to be localized along the Continental Divide.

Tuesday another trough moves across the region, but by then we are
cut off from the atmospheric river, so just some light to moderate
snow showers are expected with accumulations mainly in the
mountains and very minimal impacts in the valleys.

Wednesday through the end of the week the region is under
northwest flow. This is a very good pattern for some snow showers,
and some long term models are showing the potential for those
showers to organize into bands, but most models are showing low
level winds too weak to organize the showers into any sustained
bands. In the valleys, precipitation type and any accumulation
will strongly depend on the time of day the showers occur. With
afternoon highs in the upper 30s, precipitation in the valleys
will probably be rain or at least snow will not accumulate until
closer to evening when temperatures decrease to near freezing.




&&

.AVIATION...MVFR and IFR conditions will continue this morning at
terminals KGPI and KMSO. The region has received so much rain
recently and temperatures remain near freezing, anytime the winds
go light fog is a possibility. Today is the last day of the
atmospheric river over the region with snow levels dropping
tonight. As the snow levels drop, the precipitation will decrease,
so snow accumulation at area terminals is expected to be less than
an inch by Sunday morning.


&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...Winter Weather Advisory until noon MST today for
     Kootenai/Cabinet Region.

     Winter Weather Advisory until 5 PM MST this afternoon for West
     Glacier Region.

ID...None.
&&

$$