Bigfork, Montana Weather Forecast Discussion

595
FXUS65 KMSO 162006
AFDMSO
Area Forecast Discussion
National Weather Service Missoula MT
206 PM MDT Tue Sep 16 2025
.DISCUSSION...
KEY MESSAGES:
- Lingering showers this afternoon, primarily in southwest
  Montana along the Continental Divide.
- Cool mornings with patchy frost and fog are possible through
  Friday morning, especially in higher valleys, before giving way
  to warm, sunny afternoons.
An upper-level low pressure system is slowly circulating over
northwest Wyoming this afternoon. The counter-clockwise flow
around this low is wrapping lingering moisture and instability
into southwest Montana and along the Continental Divide. As a
result, scattered showers have been developing. High-resolution
models suggest that this shower activity will continue to expand
in coverage through the afternoon, with the highest concentration
expected near and south of Anaconda and Butte. These showers will
mainly be light to moderate in intensity with isolated lightning
strikes.
As the low pressure system continues to move southeastward and
away from our area tonight, the shower activity will diminish and
eventually dissipate. With clearing skies and light winds, low-
lying valleys, particularly those that received some rainfall, may
see the development of patchy fog toward morning.
High pressure will build in from the west on Wednesday, bringing
an extended period of dry conditions with warm afternoons for the
latter half of the work week. Expect mostly sunny skies and
afternoon high temperatures climbing into the 70s and low 80s,
which is 5-10 degrees above normal for this time of year.
While the afternoons will be warm, the combination of clear skies
and a dry airmass will allow temperatures to drop efficiently
after sunset. Morning lows are expected to fall into the 40s each
night in most valleys and 30s in the higher valleys. This will
create the potential for patchy frost formation, especially in the
typically colder, high-elevation valleys along the Divide.
By late Friday and into the weekend, forecast models show the
ridge of high pressure beginning to flatten out as a trough
approaches from the Pacific. This will open the door for a return
to a more active weather pattern. Moisture will begin to increase,
and with it, the chances for showers will return to the forecast
on Sunday. At this time there is only a slight chance for
thunderstorms. Temperatures are also expected to cool slightly,
trending back toward seasonal averages.
&&
.AVIATION...
An upper-level low over Wyoming will continue to
circulate moisture into southwest Montana and along the Divide
this afternoon. This will result in scattered showers and
potential MVFR conditions, primarily impacting the KBTM terminal.
An isolated lightning strike or two cannot be ruled out.
Showers near KBTM are expected to be light and will diminish this
evening as the low-pressure system moves away. After the
precipitation ends, clearing skies and light winds will create
favorable conditions for the formation of patchy fog or low
stratus overnight into Wednesday morning. This may lead to a
period of MVFR or even brief IFR conditions between 10Z and 16Z
Wednesday. High pressure builds in on Wednesday, bringing dry and
stable weather for the remainder of the week.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...None.
ID...None.
&&
$$

NWS MSO Office Area Forecast Discussion