280
FXUS65 KTFX 180111
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
611 PM MST Wed Dec 17 2025

.KEY MESSAGES...

 - High-end and dangerous winds continue through the remainder of
   the day, slowly diminishing this evening and tonight.

 - Colder air moving in will result in a few areas of lower
   elevation snow near the Hi-Line, with slick conditions
   developing in areas where roads are wet heading into the
   evening.

 - After a bit of a lull on Thursday, another period of gusty
   winds develops across the region Thursday night into Friday.
   Although winds and gusts look to be lower in magnitude compared
   to the ongoing event, any infrastructure stressed or
   compromised during today will be prone to impacts at lower
   thresholds.

&&

.UPDATE...

An area of light to briefly moderate snow will continue through 8
PM or so across Fergus county and adjacent areas. Combine this
with strong winds continuing through the evening and the risk for
blowing snow will persist for at least a couple more hours. As
such, a Winter Weather Advisory has been added to these areas
through 11 PM describing forecast concerns.

Ongoing High Wind Warnings will continue for the time being,
though areas near the Continental Divide have already begun to
trend downward for the event. The plan for the time being is to
allow for the High Wind Warnings to continue for at least a couple
more hours in these areas to ensure the risk for the strong winds
has diminished. -AM

&&

.DISCUSSION...
/Issued 433 PM MST Wed Dec 17 2025/

 - Meteorological Overview:

The remainder of today:

Sharp upper level troughing, strong low to mid-level flow, among
other strong forcing mechanisms is resulting in dangerous winds
across the region. Travel will be very difficult to impossible
through the remainder of the afternoon and is highly discouraged
unless absolutely necessary. Winds gradually decrease from west to
east this evening and early overnight.

Moisture wrapping around surface low pressure in far SW SK will
result in a couple hour period of falling and blowing snow in the
Havre area and vicinity late this afternoon and evening. Visibility
of one-half mile or less is expected at times in these areas. In
addition, northwest winds moving in with this snow will result in a
quick transition colder, which combined with the snow should result
in slick roads. A Winter Weather Advisory was issued for this area
through the evening.

Mountain snow gradually diminishes through the evening, with
additional snow amounts mainly less than a few inches.

Thursday and Friday:

Brief transient shortwave ridging will result in a more benign
period of weather during the day Thursday, though ample moisture
will begin to move in ahead of a Pacific trough in the afternoon and
early evening. Snow gradually develops in areas along the
Continental Divide Thursday afternoon, persisting through Friday. A
Winter Weather Advisory has been issued for areas across NW
Beaverhead, where snow is forecast to begin by Thursday afternoon.
Additional Winter Weather Advisories will be needed for the Rocky
Mountain Front beginning Thursday evening, including Marias Pass,
though for simplicities sake I have held off from issuing these
until the ongoing Winter Storm Warning expires.

All the while, strong cross barrier flow will develop once again
beginning Thursday evening. This will result in another windy
period, though the magnitude of winds and gusts will be lesser than
the ongoing event. It should be noted that infrastructure weakened by
the winds today may have lower thresholds to see impacts Thursday
night into Friday. Hence, even though forecast winds are lower than
what is being observed today, impacts from the wind to
infrastructure may be similar.

Saturday into early next week:

Persistent southwesterly flow aloft this weekend into next week will
keep low-end precipitation chances in the forecast, primarily along
the Continental Divide into early next week. Temperatures look to be
on the warmer side of average over this timeframe, though not overly
warm. -AM


 - Forecast Confidence & Scenarios:

Winds today:

Strong winds will continue through the remainder of the afternoon
slowly decreasing into the evening.

Surface low pressure over SW SK has resulted in another cold front
dropping south from Canada late this afternoon. Winds behind this
front will gradually decrease further west near Glacier county, while
areas closer to the surface low in SW SK will continue to see strong
wind gusts, potentially in excess of 80 kts near northern Blaine
County, through the remainder of the evening.

Snow showers, colder temperatures, and slick roads this evening:

Cold temperatures and an area of snow will develop behind the
Canadian cold front through the evening across the Hi-Line, with
areas most favored for impacts across Hill and northern Blaine
counties. Given snow is forecast to be rather brief in this area,
resulting in only a couple hours or greatly reduced visibility, we
opted for a Winter Weather Advisory over a Blizzard Warning. Cold
temperatures moving in behind this front will result in slick roads
where any wet roads quickly freeze.

Winds Friday:

Winds begin to increase again Thursday evening into the day on
Friday. As mentioned above, although this wind event will be lower
in magnitude compared to what is ongoing, stressed infrastructure
may see greater impacts than normal. Recovery efforts may be
impacted by the next period of winds Thursday night into Friday.
Overall, areas with a 50% probability or greater to see a 58 mph
gust include the Browning to Cut Bank areas, the Rocky Mountain
Front and adjacent plains, the Great Falls to Stanford areas,
Bozeman, and Ennis, among other areas in Southwest Montana. -AM

&&

.AVIATION...
18/00Z TAF Period

The initial concern this TAF period will be for lingering strong
winds gusts, primarily across eastern areas (Including KHVR and
KLWT). A Canadian cold front has resulted in a wind shift across
most of the plains, which has also resulted in areas of snow and
blowing snow in the KHVR vicinity. The winds, falling snow, and
blowing snow will all decrease/diminish later this evening and early
overnight.

Elsewhere surface winds will continue to decrease in magnitude,
though lingering stronger winds off the surface will result in
LLWS concerns. Mountain wave activity will also slowly diminish
through the evening and early overnight.

Looking ahead to Thursday, the main impact looks to be increasing
mountain obscuration and mountain precipitation along the
Continental Divide in the afternoon. -AM

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  25  46  37  48 /  20  10  30  30
CTB  20  39  28  40 /  40   0  30  10
HLN  26  40  33  47 /  20  30  70  80
BZN  23  40  32  52 /  20  30  50  80
WYS  11  30  22  37 /  20  90 100  90
DLN  23  39  32  49 /  20  40  70  70
HVR   8  35  24  40 /  30   0  30  10
LWT  17  41  30  47 /  50  10  20  40

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning until 11 PM MST this evening for East
Glacier Park Region-Southern Rocky Mountain Front.

High Wind Warning until midnight MST tonight 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 Weather Advisory until 11 PM MST this evening for Bears
Paw Mountains and Southern Blaine-Fergus County below 4500ft-
Gallatin and Madison County Mountains and Centennial Mountains-
Hill County-Little Belt and Highwood Mountains-Northern Blaine
County-Northwest Beaverhead County-Ruby Mountains and Southern
Beaverhead Mountains-Snowy and Judith Mountains.

Winter Weather Advisory from 2 PM Thursday to 9 PM MST Friday
for Northwest Beaverhead County.

&&

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