Dillon, Montana 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

329
FXUS65 KTFX 221150
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
450 AM MST Mon Dec 22 2025

Aviation Section Updated.

.KEY MESSAGES...

- Occasional light freezing rain and drizzle will impact
  the Bozeman, Dillon, and Helena areas through the mid to late
  morning hours today.

- Periods of mountain snow and some scattered areas of lower elevation
  light rain, snow, or mixed precipitation continue for much of
  the week.

- Near to above average temperatures are expected for
  most locations, but Arctic air will periodically move into
  central and north- central Montana.

&&

.DISCUSSION...
/Issued 341 AM MST Mon Dec 22 2025/

 - Meteorological Overview:

Another wave of mountian snow and scattered areas of lower
elevation rain/snow will continue to move through the forecast
area through mid- to late morning. The primary concerns continue
to be light snow impacts at the passes, along with some light
freezing rain/drizzle over the colder valleys of southwest and
central/north-central MT thanks to H700 temperatures warming to
the -2 to -6C range and below freezing ground surfaces.

Precipitation diminishes and ends this afternoon with the passage
of the responsible shortwave trough. Arctic air will move back
southward and brush north-central Montana this evening and
tonight, mostly impacting areas along the Hi-Line. A deepening
trough along the Pacific NW coast will send another elevated warm
front through the forecast area on Tuesday, resulting in more
mountain snow and some lower elevation precipitation. Recent model
guidance has been running a little less bullish with
precipitation east of the Continental Divide for the Tuesday
through early Wednesday period, but at least some scattered areas
of light precipitation can be expected. The warming aloft will
also bring another opportunity for spotty, light freezing
rain/drizzle over the colder valleys.

The better chance of precipitation will come Wednesday into
Thursday when a shortwave ejects northeastward into the Northern
Rockies. The most notable change with this system from 24 hours
ago is the warmer temperatures aloft. While there is still an
expectation for surface level Arctic air to dive back southward
into central/north-central MT, the shallow cold profile no longer
looks to be supportive of widespread lower elevation snowfall, but
rather lighter snow and mixed precipitation, including light
freezing rain and drizzle. Mountain areas still look good for
light accumulating snow during this time.

The aforementioned trough churning along the Pacific NW coast
looks to finally head eastward into Montana Friday into Saturday
for another round of snow and a southward intrusion of Arctic air.
The cold air depth with this system should be sufficient for snow
at all elevations, but still most widespread in the mountains.
Ridging aloft then settles in for milder conditions later in the
weekend into early next week before troughing and colder air
returns heading into the new year. - RCG

 - Forecast Confidence & Scenarios:

Snow and spotty light freezing rain/drizzle through the morning
hours...

Waves of precipitation continue to stream in from the southwest
while colder valley locations along the Continental Divide and
over southwest MT remain below freezing. Winter weather advisories
were sent out to include the Bozeman and Dillon areas for ongoing
light freezing rain. Helena and Lincoln were also added in
anticipation for the development of light freezing rain later this
morning. Areas along the Hi-Line have remained dry thus far but
no changes were made to the inherited advisory. While hires
guidance has backed precipitation off some, at least spotty
freezing drizzle can`t be ruled out. Farther north, the immediate
eastern slopes of the Rocky Mountain Front were added to the
advisory due to ongoing light snow. Impacts for this morning will
be greatest for the areas observing freezing rain and may include
slippery roads/sidewalks causing hazardous conditions for
travelers/pedestrians, isolated power outages, and aviation
impacts.

More light freezing rain or drizzle possible Tuesday through
Thursday...

At this time, precipitation on Tuesday into early Wednesday looks
minimal for most locations east of the Continental Divide. The
main concerns come with the arrival of a shortwave trough and the
southward advancement of an Arctic boundary. If this trough does
indeed lack colder air aloft, then central and north-central
Montana will be looking at scattered areas of light freezing
rain/drizzle late Wednesday through early Thursday morning while
temperatures fall in teens and 20s. NBM probabilities weakly
highlight this potential with around a 10 to 20% chance for a
hundredth or greater of ice accumulation. This situation will be
closely monitored as time progresses. - RCG

&&

.AVIATION...
22/12Z TAF Period

A passing shortwave will maintain areas of light snow, rain, and
freezing rain through 22/18Z, mostly concentrated along the
Continental Divide and over Southwest MT. KBZN and KHLN will be
most susceptible to light freezing rain/drizzle and MVFR/IFR
conditions. Precipitation diminishes and ends this afternoon with
partial clearing taking place and VFR conditions returning. - RCG


&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  46  27  45  27 /  30   0   0   0
CTB  38  15  39  19 /  20   0   0  10
HLN  43  28  46  31 /  80  10  20   0
BZN  46  30  50  32 /  60  20  10   0
WYS  41  30  42  27 /  90  90  40   0
DLN  46  30  47  32 /  60  20  10   0
HVR  35  11  33  20 /  40   0   0  10
LWT  46  27  48  33 /  40  10   0   0

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 11 AM MST this morning for
Beaverhead and Western Madison below 6000ft-Big Belt, Bridger
and Castle Mountains-Canyon Ferry Area-East Glacier Park Region-
Eastern Toole and Liberty-Elkhorn and Boulder Mountains-Gallatin
Valley-Gallatin and Madison County Mountains and Centennial
Mountains-Helena Valley-Hill County-Northern Blaine County-
Northwest Beaverhead County-Southern Rocky Mountain Front-Upper
Blackfoot and MacDonald Pass-Western and Central Chouteau County.

&&

$$
http://www.weather.gov/greatfalls