Thompson Falls, Montana Weather Forecast Discussion

587
FXUS65 KMSO 172028
AFDMSO
Area Forecast Discussion
National Weather Service Missoula MT
228 PM MDT Wed Sep 17 2025
.DISCUSSION...
KEY MESSAGES:
- The warming and drying trend will last through Saturday,
  bringing sunny skies and temperatures 10-15 degrees above
  average.
- Gusty winds of 30-40 mph are expected on Sunday with choppy
  conditions on area lakes, including Flathead Lake
- Shower and thunderstorm chances have increased for Sunday
A strong ridge of high pressure is building over the Northern
Rockies, ushering in a period of quiet, dry, and warm weather.
For this afternoon and the next three days, expect widespread
sunshine and a steady warming trend. Afternoon high temperatures
will climb into the mid-to-upper 70s, with some of the warmer
valleys potentially touching 80 degrees by Friday and Saturday.
These temperatures are well above normal for mid- September.
Overnight conditions will remain clear and cool. Lingering low-
level moisture will again lead to patchy valley fog Thursday
morning, which may again impact the Butte area.
The tranquil weather pattern will come to an end this weekend. A
Pacific trough is forecast to dig into the region on Sunday,
causing the ridge to break down. The primary impact will be an
increase in wind speeds. Southwesterly winds are expected to
become very gusty on Sunday, commonly reaching 30 to 40 mph.
These strong winds may create hazardous recreational conditions
on area lakes. Boaters should anticipate very choppy water,
especially on Flathead Lake. In addition to the wind, the
approaching system will bring increasing clouds, cooler
temperatures, and a widespread chance for showers beginning Sunday
afternoon and continuing into Monday.
Decent agreement remains (80% of ensemble clusters) on brief
ridging (warming/drying) again early next week (Sept 22-23). The
pattern looks progressive with another trough over the Pacific
Northwest by Sept 24-25th but the details are limited.
&&
.AVIATION...
VFR conditions will prevail across north-central Idaho and western
Montana through Friday under a strong high-pressure ridge. The
main aviation concern during this period will be the potential for
some morning valley fog, which may again cause IFR impacts at
KBTM Thursday morning.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...None.
ID...None.
&&
$$

NWS MSO Office Area Forecast Discussion