084
FXUS65 KTFX 152324
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
424 PM MST Mon Dec 15 2025

Aviation Section Updated.

.KEY MESSAGES...

- Strong, gusty winds peak along the Rocky Mountain Front this
  afternoon and then over central and north-central Montana later
  this evening through early Tuesday.

- A dynamic Pacific front brings widespread strong to damaging
  winds and locally intense snow showers on Wednesday.

- The colder air sags southward into north-central Montana for the
  second half of the week while mostly mountain snow.

&&

.DISCUSSION...
/Issued 302 PM MST Mon Dec 15 2025/

 - Meteorological Overview:

Weak ridging aloft will maintain well above normal temperatures
today while strong cross barrier flow and mountain wave activity
maintain periods of strong, gusty winds along the Rocky Mountain
Front and much of north-central MT through Tuesday morning. H700
flow will roughly run between 60 and 80 kts with mountain waves
transferring the strongest winds to the surface along the Rocky
Mountain Front through this evening and a shortwave passage
bringing peak winds over the plains this evening through early
Tuesday.

Height falls and cooling aloft will bring slightly cooler, but
still above average temperatures on Tuesday with winds diminishing
some by the afternoon hours. Pacific moisture streaming towards
the Continental Divide will bring periods of light snow to the
immediate eastern slopes of the Rocky Mountain Front. Otherwise,
Tuesday looks rather tranquil compared to what`s coming on
Wednesday.

The well advertised potent Pacific trough and attendant cold
front is still progged to sweep through the state on Wednesday and
bring at least a several hour period of widespread strong, to
damaging winds. This system will be driven by strong cold air
advection and H850/H700 flow in the 55 to 85 kt range, both of
which look to occur during peak diurnal mixing. The sharp
frontogenesis with this system quickly drops H700/H500
temperatures to around -15C/-30C behind the front, encouraging
scattered locally intense snow shower/squall development. The
central and southwest mountain passes look to be the target for
the most impacts from this convective snow activity Wednesday
morning/early afternoon and then it shifts to along the Hi- Line
in the evening hours per the Canadian Front. There will also be
ongoing snow along the higher terrain of the Rocky Mountain Front
that become heavy at times Tuesday night into Wednesday,
particularly above pass level.

Colder air will briefly clip northern areas on Thursday in the
wake of the passing trough/cold front before milder air moves back
in ahead of the next Pacific trough. There will be a couple of
Pacific troughs that traverse the Northern Rockies through early
next week. Each will bring a period of increased mostly mountain
snow followed by modest intrusions of Arctic air, primarily
clipping northern areas. Timing for these trough/cold fronts look
to be late Thursday through early Saturday and again Sunday into
Monday. - RCG

 - Forecast Confidence & Scenarios:

Periods of strong winds along the Rocky Mountain Front and
central/north-central MT through Tuesday morning...

Strongest winds this afternoon will continue to favor the Rocky
Mountain Front and the plains along and west of highway 89 where
wind gusts are exceeding the 75 to 90 mph range at times. The
normally wind prone locations such as Bynum, Deep Creek, and East
Glacier/Browning areas will be most prone to gusts exceeding 90 mph.
Farther east, the strongest winds look to occur with the ejecting
shortwave trough this evening through early Tuesday when 50 to 70
mph gusts will be more common.

The main uncertainty with this event is the nighttime peak of upper
level winds possibly reducing the occurrence of stronger gusts
mixing to the surface. This will be most pronounced over some of the
more wind protected valleys, including the Milk River Valley
vicinity. Higher end probabilities (70%+) for gusts over 55 mph are
a little spottier here, but given some of these areas already
reached high wind criteria and the upper level flow strengthens
tonight during the shortwave passage, at least localized warning
criteria gusts seem plausible. The secondary uncertainty will be
central and southern areas along and north of the I90 corridor. Some
of these mountain passes may have brief periods with gusts exceeding
60 mph as will the Canyon Ferry area. Left these locations out of
the warning for now given limited opportunity and lower end
probabilities (generally less than 50%) for gusts over 55 mph.

Impacts will continue to include difficult to dangerous travel
for high profile vehicles, localized blowing dust near open
fields, and the movement of unsecured outdoor items, including
Christmas decorations. Additional power outages also can`t ruled
out, particularly for areas that observe the higher end gusts.

Widespread strong to damaging winds and localized intense snow
showers/squall on Wednesday...

Conditions continue to be favorable for a widespread strong to
damaging wind event across southwest and central/north-central MT on
Wednesday. Strong cold air advection and peak H700 flow in the 60 to
90 kt range looking to occur during maximum diurnal mixing is
concerning at this point to say the least. Some caveats that would
weaken or preclude the winds such as a stronger/faster Canadian
front undercutting the strong winds aloft and shifts in frontal
passage timing are starting to lose steam. Just of note, H850 winds
behind the Canadian front are now highlighting north/northwesterly
H850 winds in excess of 50 kts. Additionally, this event look to be
of longer duration (multiple hours of very windy conditions vs the
typical 1-3 hr peak period). Given the wide swath of 60 to 80 mph
wind gusts expected, impacts look to include difficult to dangerous
travel for high profile vehicles, downed trees/property damage, and
scattered power outages. All the watches for Wednesday have been
upgraded to a warnings and now include the entire forecast area.
In addition to the winds, there will be sufficient instability and
dynamics for locally intense snow shower/squalls, particularly
for central and southwest Montana. Moderate to heavy snow will
also be ongoing along the higher terrain of the Northern Rocky
Mountain Front and a brief period of gusty accumulating snow may
even work its way southward to the Hi-Line Wednesday evening via
the Canadian cold front. - RCG

&&

.AVIATION...
16/00Z TAF Period

VFR conditions will prevail across all terminals during the duration
of this TAF Period. It will be very windy at the KGTF, KCTB, and
KHVR terminals from now through about 16/18Z. From now through
16/14Z there will be wind gusts in excess of 55 kts at the KCTB
terminal and 45 kts at the KGTF terminal. There will be instances
of low-level wind shear and mountain wave turbulence during the
duration of this TAF Period across North-central, Central, and
Southwestern Montana. -IG


&&

.HYDROLOGY...

Mild daytime and overnight temperatures will lead to rapid melting
of the recent snow across eastern portions of north-central MT. With
initially frozen ground, much of the snowmelt is likely to remain
on the surface and may lead to standing water. While overall
impact to creek/stream levels is low, most creeks are likely to be
frozen with potential for water flow over the ice or potentially
back up in some creek bottoms. Hoenisch

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  42  52  40  50 /   0  10  20  60
CTB  35  45  33  45 /  10  10  40  50
HLN  38  52  36  48 /  20  20  30  90
BZN  36  55  36  51 /  10  20  10  90
WYS  24  40  30  39 /  10  30  50 100
DLN  37  54  36  47 /  10  10  10  90
HVR  30  44  30  43 /   0  20  30  50
LWT  36  46  34  48 /  10  10  10  60

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
High Wind Warning until 11 AM MST Tuesday for Bears Paw
Mountains and Southern Blaine-Cascade County below 5000ft-
Eastern Pondera and Eastern Teton-Fergus County below 4500ft-
Hill County-Judith Basin County and Judith Gap-Little Belt and
Highwood Mountains-Madison River Valley-Northern Blaine County-
Snowy and Judith Mountains-Upper Blackfoot and MacDonald Pass-
Western and Central Chouteau County.

High Wind Warning from 3 AM Wednesday to midnight MST Wednesday
night for Bears Paw Mountains and Southern Blaine-Beaverhead and
Western Madison below 6000ft-Big Belt, Bridger and Castle
Mountains-Canyon Ferry Area-Cascade County below 5000ft-East
Glacier Park Region-Eastern Glacier, Western Toole, and Central
Pondera-Eastern Pondera and Eastern Teton-Eastern Toole and
Liberty-Elkhorn and Boulder Mountains-Fergus County below 4500ft-
Gallatin Valley-Gallatin and Madison County Mountains and
Centennial Mountains-Gates of the Mountains-Helena Valley-Hill
County-Judith Basin County and Judith Gap-Little Belt and
Highwood Mountains-Madison River Valley-Meagher County Valleys-
Missouri Headwaters-Northern Blaine County-Northern High Plains-
Northwest Beaverhead County-Ruby Mountains and Southern
Beaverhead Mountains-Snowy and Judith Mountains-Southern High
Plains-Southern Rocky Mountain Front-Upper Blackfoot and
MacDonald Pass-Western and Central Chouteau County.

Winter Storm Watch from Tuesday evening through Wednesday
evening for East Glacier Park Region-Southern Rocky Mountain
Front.

High Wind Warning until 8 AM MST Tuesday for East Glacier Park
Region-Eastern Glacier, Western Toole, and Central Pondera-
Eastern Toole and Liberty-Northern High Plains-Southern High
Plains-Southern Rocky Mountain Front.

&&

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