Polson, Montana 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

407
FXUS65 KMSO 151946
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
146 PM MDT Tue Jul 15 2025

.DISCUSSION...

KEY MESSAGES:

- Showery and cool through Wednesday morning, mountain valley
  frost/fog potential.

- Mostly dry rest of the week, warming to near and above normal.

- A couple weak disturbances increasing afternoon wind potential
  Thursday and Saturday.

- Another cool down with showers early next week?

Visible satellite imagery this afternoon shows a large shield of
cloud cover across most of the state of Montana with clearing
toward the west. Water vapor imagery helps locate the center of
low pressure moving slowly southeastward out of far NW Montana.
To the east of this low, rain showers and a few embedded
thunderstorms are continuing to reinforce soggy conditions over
much of Western Montana. Through the first half of the day,
temperatures in locations underneath the showers and cloud cover
have either cooled subtly or remained about the same as overnight
temperatures due to continued cold air advection into the region
and limited solar heating.

As this low continues to move eastward and out of the forecast
area overnight into Wednesday, north winds will continue to remain
elevated, with widespread gusts in the 30 mph range, near and
along the Continental Divide. These winds will gradually decrease
late tonight. In areas with sufficient solar heating to the south
of the overcast skies, such as southern Lemhi County, some
convection is possible through the evening hours that could
produce lightning, gusty winds in excess of 35 mph, and small hail
in stronger storms.

With clearing skies and cold air in place tonight, some mountain
valleys that have received wetting rain are at risk of fog
developing overnight. One place in particular to watch would be
the Flathead Valley where over a quarter inch of rain has been
measured in the last day. At some higher elevation valley
locations, such as the Seeley Lake and Polebridge areas, light
frost is possible for Wednesday morning with temperatures dropping
into the low-to-mid 30s.

Anticipate a quick rebound with warmer days ahead as flow aloft
becomes west-northwesterly through the rest of the week and the
airmass begins to moderate under drying conditions.

A weak disturbance lacking substantial moisture is forecast to
ride along the Canadian border Thursday bringing some showers
isolated to far northern Montana. For the rest of the region, an
increase in afternoon wind speed and gusts is expected. This will
be an interesting time period for fire weather concerns as low
daytime relative humidities (below 20%) return to much of the
region.

Through the coming weekend, another mostly-dry trough will move
through the area, keeping temperatures from reaching their maximum
potential for the time of year, but again bringing an uptick in
fire weather concerns.

By the Tuesday-Wednesday timeframe of next week, models are
beginning to pick up on another chance for a cool and wet storm
to impact the region. Exact details on timing, track, and
intensity of this storm are still too far out to hone in on.


&&

.AVIATION... Two main modes of precipitation are depicted on
radar this afternoon. One area of stratified light precipitation
north of I-90 and deeper, more vigorous convection and
thundershowers toward southern Lemhi County and extreme southwest
Montana. Precipitation will continue to reinforce low ceilings
and terrain obscurations in areas near GPI/BTM through about
16/0300Z. Drying and clearing follows for Wednesday.
Thunderstorms in the far southern portions of the forecast area
will be capable of producing outflow gusts in excess of 35 knots.
Background northerly surface winds gusting up to 35 knots will
continue near the Continental Divide this evening eventually
subsiding overnight. Valley locations that have received wetting
rainfall over the last day (such as GPI) will be susceptible to
fog formation Wednesday morning. Ridgetop winds decrease into
Wednesday before becoming westerly and restrengthening into
Thursday.



&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...Wind Advisory until 2 PM MDT this afternoon for Flathead/Mission
     Valleys...Kootenai/Cabinet Region...West Glacier Region.

     Wind Advisory until 8 PM MDT this evening for Butte/Blackfoot
     Region...Potomac/Seeley Lake Region.

ID...None.
&&

$$