866
FXUS65 KTFX 152057
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
157 PM MST Sat Nov 15 2025

.KEY MESSAGES...

- Dry this afternoon with breezy winds decreasing this evening.

- Potential for dense fog along the Hi Line tonight and Sunday
  morning.

- Temperatures drop back towards average next week, with a few
  rounds of light mountain snow and lower elevation rain.

&&

.DISCUSSION...

 - Meteorological Overview:

Slight ridging moving in this afternoon has helped pushed out
morning precipitation. Mid level winds decreasing this afternoon and
evening will decrease the breezy winds mixing down along the
stationary front this afternoon after peak heating. The main
concern overnight tonight is relative humidities raising near or
at 100% and light winds along the Hi-line/northern Chouteau County
will produce freezing fog. Although a broken low stratus deck
will set up along the Milk River Valley tonight, high relative
humidities already this afternoon gives some concern of fog
developing tonight despite cloud cover. Hi-res guidance gives a
40-80% chance for visibility down to a half mile or less in this
region. Therefore, there`s a good chance for dense fog if fog
develops, and a Dense Fog Advisory may be needed later tonight if
it materializes widespread. Areas that get dense freezing fog may
develop icy spots on pavements and cause hazardous driving
conditions.

A closed wave in the Great Basin region moving northwest early this
week will bring the next chances for precipitation. However, this
closed wave is forecasted to weaken and "open up" as it reaches
the Interior Mountain West. Weakening forcing aloft combined with
warmer temperatures aloft will keep precipitation and mountain
snow light overall. Behind this, another splitting trough looks to
move through late Tuesday/Wednesday, but differences in
positioning gives some uncertainty of how much precipitation
falls. Another trough looks to form along the Western U.S. towards
the end of next week. Since the the main core of this trough
looks stays off to the south, I am not too concerned of any major
impacts at this time.

 - Forecast Confidence & Scenarios:

Slight differences in the evolution in this weakening wave and
weak troughing the beginning of the week still gives a broader
range of precipitation amounts. The 25th percentile of the NBM
gives lower elevations up to 0.05" of precipitation Monday-
Wednesday, 0.15-0.20" in the Southwest MT and 0.25-0.3" along the
Northern Continental Divide. The 75th percentile NBM gives lower
elevations 0.15-0.30" of precipitation, 0.60-0.75" in the
Southwest MT and 0.60-0.80" along the Northern Continental Divide.
Even if the higher precipitation amounts accumulate, snow in the
mountains will stay minor. There`s a 20-40% chance for 3" of snow
in the mountains during this time period, with most impacts
staying above pass level. -Wilson

&&

.AVIATION...
15/18Z TAF Period

Low to mid-level clouds will linger through the first 6 hours of
the period across central and southwest Montana creating periods
of mountain obscuration through 16/00Z. Gusty winds will be
possible along the Rocky Mountain Front into portions of central
Montana with gusts up to 40kts possible for KGTF and KCTB.

Between 16/00Z and 16/10Z, winds will become lighter and cloud
decks are expected to lift with only few to scattered high clouds.

After 16/10Z, another round of low to mid-level clouds returns to
central and southwest Montana bringing back concerns for mountain
obscuration through the remainder of the period as well as a 30%
chance for rain/snow mix for portions of southwest Montana.

Dense fog will be a concern across the Hi-Line after 16/08Z with
the greatest impacts expected for KHVR. Right now there is high
confidence in visibility down to 1SM, however, hi-res model
guidance is pointing towards at least a 50% chance for
visibilities less than 1/4SM between 16/10Z and 16/16Z. For now,
the TAF will prevail IFR conditions but periods of LIFR/VLIFR
cannot be ruled out.  -thor

The KWYS TAF will not be issued until airport operations resume
next spring.

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  35  56  40  55 /   0   0  10  30
CTB  29  50  34  54 /   0   0  10  10
HLN  35  55  38  53 /   0  10  20  50
BZN  32  57  36  52 /   0  10  20  50
WYS  26  48  30  40 /   0  50  70  80
DLN  33  56  35  50 /   0  10  20  40
HVR  27  49  34  50 /   0   0  10  30
LWT  33  58  37  53 /   0   0  10  30

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
None.
&&

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