313
FXUS65 KTFX 162332
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
432 PM MST Tue Dec 16 2025

Aviation Section Updated.

.KEY MESSAGES...

 - Dangerously strong winds expected across North Central and
   Southwestern Montana on Wednesday, scattered wind gusts to 80
   mph expected for much of the day.
 - In addition to the winds, localized snow squalls will be
   possible, especially along and south of Interstate 90.
 - Another, but not as strong, wind event is possible on Friday.
 - Periodic active weather could hamper repair/recovery operations
   through early next week.

&&

.DISCUSSION...
/Issued 328 PM MST Tue Dec 16 2025/

...A significant, long lasting, and potentially destructive wind
event is expected on Wednesday...

While not as strong as yesterday, gusty winds have continued
across North Central and Southwestern Montana today as strong
upper level flow persists across the area. Unfortunately, these
winds are going to be mild compared to what is expected tomorrow,
as an unusually strong shortwave trough moves across the Northern
Rockies. As this trough swings through the area, incredibly strong
winds aloft will have little issue translating to the surface
thanks to dynamic forcing, cold air advection aloft, and the
development of a lee trough east of the Rocky Mountain Front. This
combination is poised to bring a significant and dangerous
windstorm, with models showing widespread wind gusts to 75 mph or
higher, with 100 mph possible along the immediate Rocky Mountain
Front. The main messages with this system are as follows:

 1. This is a long duration wind event, likely lasting in excess
    of 8 hours for some locations.
 2. Winds may pick up incredibly quickly tomorrow morning and/or
    early tomorrow afternoon.
 3. Forecasted wind speeds are significant, even by Montana
    standards.

In addition to the strong winds tomorrow, we will also have to be
on the lookout for snow squalls, particularly along and south of
Interstate 90. These squalls, in addition to the strong winds that
will start around or immediately after they hit, may be
especially dangerous with the combination of rapid and significant
reductions in visibility, and these squalls may also produce a
rapid accumulation of snowfall on the roads which will make them
incredibly dangerous. Further, snow will also be found in some of
the higher terrain tomorrow, which will result in poor visibility
due to falling and blowing snowfall. Any sort of travel plans
across North Central or Southwestern Montana should be
reconsidered if at all possible.

Thursday will see a brief break in the action as ridging
temporarily builds back into the area, but Friday will see another
round of winds and mountain snowfall make their way through the
area. Fortunately, this Friday system is not expected to be
anywhere near what tomorrow will bring. Active weather is likely
to continue into next week, which may complicate any
recovery/repair work that is continuing Friday through early next
week.

 - Forecast Confidence & Scenarios:

Overall confidence in tomorrows busy forecast is very high, with
high winds a near certainty across almost all of the forecast
area. Where there does remain some concern, however, is that there
are some indications that winds could unfortunately wind up
stronger than forecast, especially if a mountain wave forms or any
rain/snow showers are able to accelerate the winds as they mix to
the surface. A few models have indicated boundary layer heights
reaching the same heights as where winds in excess of 80 knots/90
mph will exist. While winds should decelerate a bit on their way
to the surface due to friction, I cant definitely rule out some
wind gusts in excess of 85 or 90 mph in some of the cities in our
forecast area, including Bozeman, Cut Bank, Great Falls, and
Helena. While these extreme winds are on the far end of the
forecast distribution (10% chance or less), these winds would have
the potential to be quite damaging in populated areas, especially
given that this wind event is likely to last most of the day.
Ludwig

&&

.AVIATION...
17/00Z TAF Period

Initial concern this TAF period will be for lingering breezy winds
over the plains through the evening before winds gradually begin to
build up ahead of a Pacific cold front later tonight. As winds aloft
increase later tonight, instances of LLWS will be possible in areas
where surface winds are slow to increase.

Heading into Wednesday, a highly impactful day is forecast across
the region. First, a cold front will shift winds to a more westerly
direction through the morning. Across Southwest Montana this cold
front will come with a band of precipitation, which may briefly be
snow at valley floors. Although not included in TAFs across SW MT at
this time, the cold front has just enough instability to result in a
few lightning strikes Wednesday morning. Confidence was not high
enough to warrant that mention, however.

Strong gusts will accompany this front across the entire region,
which will set the stage for strong surface winds and gusts through
the day Wednesday. Gusts in excess of 50 kts will be common behind
the front through the day Wednesday. Low-level turbulence and
mountain wave turbulence will be common, especially behind the
cold front, and be highly impactful to all aviation interests.
Winds gradually subside late Wednesday into Wednesday night. -AM

&&

.FIRE WEATHER...

While strong winds may cause increased risk of fire growth, high
fuel moisture and humidity, along with some areas of precipitation
should reduce the risk. Please see the fire weather forecast for
more information. Ludwig

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  40  50  26  47 /  10  50   0  10
CTB  34  44  21  40 /  30  40   0   0
HLN  35  47  26  41 /  30  90   0  30
BZN  36  51  23  43 /  20  90   0  30
WYS  29  40  12  31 /  70 100   0  90
DLN  36  47  23  39 /  30  80   0  40
HVR  32  45   9  36 /  20  60  10  10
LWT  36  48  18  42 /  10  60  10  10

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning from 8 PM this evening to 11 PM MST
Wednesday for East Glacier Park Region-Southern Rocky Mountain
Front.

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 Weather Advisory until 11 PM MST Wednesday for Gallatin
and Madison County Mountains and Centennial Mountains-Little
Belt and Highwood Mountains-Northwest Beaverhead County-Ruby
Mountains and Southern Beaverhead Mountains.

&&

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