585
FXUS65 KTFX 081749
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
1049 AM MST Mon Dec 8 2025

Aviation Section Updated.

.KEY MESSAGES...

- Strong winds develop later today and then continue into Tuesday.

- Mild temperatures expected at lower elevations the next few
  days.

- Daily mountain snowfall will continue, but snow levels will be
  rather high early this week.

- Still looking to get rather cold for a few days late this week,
  but warms back up over the weekend.

&&

.UPDATE...
/Issued 809 AM MST Mon Dec 8 2025/

Satellite imagery this morning shows an extensive Chinook Arch
developing across the area on the nose of fairly extensive upper
level jet and Pacific moisture plume moving into the Northern
Rockies. Main weather impact today will be the increasing winds
with strongest winds still expected to become more widespread
tonight through early Tuesday. Snow develops along the continental
divide through this afternoon with snow levels currently around
4500 ft, expected to rise to around 6500 ft by this evening as
milder flow from the Pacific continues to overspread the area.
Temperatures this morning are already in the upper 30s to around
40 across most of the plains/valleys with afternoon temps on track
to reach the upper 40s to around 50 at many lower elevation
locations, with warmest temps in areas adjacent to the east
slopes of the Rockies and just north of the Little Belts. Hoenisch

&&

.DISCUSSION...
/Issued 809 AM MST Mon Dec 8 2025/

 - Meteorological Overview:
A strong westerly flow aloft will reside over the CWA through
early Tuesday. This will result in periods of strong winds at the
surface later today and into Tuesday. A few isolated strong wind
gusts occurred overnight, but I expect the stronger wind gusts to
start to become more widespread this afternoon and evening. The
brisk westerly flow is also allowing for mild temperatures to move
into the CWA. Just a few locations along the Milk River in Blaine
County and a few locations along the Missouri River breaks area in
Fergus County have not warmed up yet. Overall, I went with near
NBM temperatures, but I did raise them in a few locations a few
degrees. Note, the GFS model is even warmer, especially on Wed.

A concern for Tue is the GFS model as the cold air moving back
down from Canada for a few hours as the area of low pressure that
causes all the wind moves off to our east. The NAM model is not as
aggressive with the cold air. However, the GFS solution could have
some more impacts if it pans out, such as colder air moving back
in, and some convective snow showers along the frontal boundary.

Otherwise, warmer air returns for Wednesday, before most models
agree that the cold air makes a return Wed night into Thu. Expect
a sharp drop in temperatures behind this cold front.

Precip -> Today through Wed -> Snow levels will be rather high
through this period, unless the GFS pans out for Tue afternoon,
lowering snow levels for a few hours. This will result in rain
falling for elevations generally below 5500 feet most days. (The
freezing level at Midnight was 7000 feet.) Thus no winter weather
advisories will be issued at this time for early this week. (That
could change if the GFS pans out for Tue though.)

Thursday through Friday...Overall the forecast models agree it
will turn colder/snowy for a few days. The GFS model continues to
be the most aggressive with the snowfall. Overall the NBM is a
good solution at this time, with snowfall amounts of 3 to 6 inches
at lower elevations over North Central MT and well over a foot in
the mountains. In Southwest MT, the snowfall will not be as much,
as the forecast models generally stall the cold front out along a
line from just south of Helena to just north of Bozeman.
Temperatures near the US/Canadian border will be quite cold on
Friday and cold weather advisory criteria might be met.

Saturday through Monday...expect a gradual warming trend, with
some light precipitation, mostly over the mountains of the Rocky
Mountain Front.

 - Forecast Confidence & Scenarios:

There is an 80 percent chance of high winds in the high wind
warning area from later today into Tuesday.

There is a 40 percent of 4 inches or more of snowfall at lower
elevations on Thursday. Thus winter statements are likely later
this week.

There is a high probability that cold weather statements will be
needed later this week, especially for areas along/north of
Highway 2. Brusda

&&

.AVIATION...
08/18Z TAF Period

VFR conditions will prevail across the KBZN, KEKS, and KHLN
terminals during this TAF Period. During the majority of this TAF
Period it will be very windy at all but the KHLN and KBZN
terminals. There will be several hours of wind gusts in excess of
50 kts at the KGTF, KEKS, and KCTB terminals after 09/06Z. There
will be instances of low-level wind shear and mountain wave
turbulence across North-central, Central, and Southwestern Montana
during the duration of this TAF Period. After 09/12Z across all
terminals there is greater than a 30% chance for rain and/or a
rain/snow mix. At the KHVR and KLWT terminals the rain and/or
rain/snow mix will lower visibility to at least MVFR-levels with a
10% chance for visibility to lower to IFR-levels or lower. During
the majority of this TAF Period there will be periods of mountain
obscuration across North-central, Central, and Southwestern
Montana. -IG

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  51  39  50  33 /  10  30  50  60
CTB  46  32  42  25 /  10  30  40  40
HLN  49  39  50  34 /  20  50  70  80
BZN  46  36  51  31 /  10  20  60  80
WYS  33  25  38  27 /  30  70  90  90
DLN  44  37  49  34 /  10  30  40  70
HVR  42  31  45  21 /  10  30  70  30
LWT  43  32  46  25 /  10  20  60  50

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
High Wind Warning from 2 PM this afternoon to 10 AM MST Tuesday
for Cascade County below 5000ft-East Glacier Park Region-Eastern
Glacier, Western Toole, and Central Pondera-Eastern Pondera and
Eastern Teton-Eastern Toole and Liberty-Gates of the Mountains-
Madison River Valley-Northern High Plains-Southern High Plains-
Southern Rocky Mountain Front-Upper Blackfoot and MacDonald Pass.

High Wind Warning from 6 PM this evening to 3 PM MST Tuesday for
Bears Paw Mountains and Southern Blaine-Big Belt, Bridger and
Castle Mountains-Fergus County below 4500ft-Hill County-Little
Belt and Highwood Mountains-Meagher County Valleys-Northern
Blaine County-Snowy and Judith Mountains-Western and Central
Chouteau County.

High Wind Warning until 3 PM MST Tuesday for Judith Basin County
and Judith Gap.

&&

$$
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