032
FXUS65 KTFX 181204
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
504 AM MST Thu Dec 18 2025

.KEY MESSAGES...

 - Relaxed winds and mainly dry conditions are expected through this
   afternoon.

 - The next period of windy conditions with locally strong gusts
   will develop tonight through Friday.

 - Snow develops along the continental divide late this afternoon and
   increases tonight with periods of moderate snowfall affecting
   passes along the divide at times tonight through Friday.

 - Some lower elevation rain and snow is possible Friday afternoon
   with dry conditions anticipated for the weekend.

&&

.DISCUSSION...

 - Meteorological Overview:

Winds have relaxed across the area beneath a transient period of
upper level ridging in the wake of yesterdays strong system. By this
afternoon surface pressure will begin to fall again as troughing
deepens to lee of the Rockies in MT and AB ahead of the next
incoming shortwave from the Pacific. Mid-level flow increases
tonight as this energy translates across southern BC to AB with
another fairly potent surface low tracking east from AB to
southern SK by Friday morning. Gusty winds will develop across
western portions of north-central MT by late this afternoon and
intensify tonight with with areas along the Rocky Mtn Front
initially seeing strong gusts as early as this evening before
stronger gusts expand east across portions of north-central MT
overnight through Friday morning. High Wind Watches have been
issued for primarily western portions of north-central MT
beginning tonight as well as for the Madison River Valley and
Norris Hill.

A plume of more concentrated Pacific moisture becomes oriented into
the Northern Rockies later today and tonight with orographically
enhanced snow developing primarily along and west of the
continental divide late this afternoon through tonight. A period
of moderate to perhaps briefly heavy snowfall is possible across
northern portions of the continental divide late tonight including
the Marias Pass area, which shifts south and affects NW portions
of Beaverhead county Friday morning.

As the surface low tracks east across southern AB/SK on Friday
gusty winds will spread east across most of the area with strong
wind potential greatest across north-central MT. A W-E axis of
precipitation looks to develop along the Pacific front trailing
south from the low across central MT by mid-day Friday with this
area of precipitation sagging south through SW MT Friday
afternoon. Cooling behind the front will lower snow-levels for
some lower elevation snowfall with impactful snow most likely to
affect the mountain ranges south of I-90 to the ID/WY border
Friday afternoon. Winter weather advisories have been issued to
highlight mainly pass level snow impacts along the continental
divide and SW MT mountains tonight through Friday.

The area remains under a fast westerly flow through the weekend,
though upper level energy and Pacific moisture are mostly directed
north of the area with mainly dry conditions likely to prevail
through Sunday. Hoenisch

 - Forecast Confidence & Scenarios:

There is a 60% or higher probability of gusts in excess of 55 mph
where High Wind Watches have been issued. A 30-50% probability
for gusts of this magnitude exists for much of the remainder of
the forecast area and later shifts may expand high wind highlights
if further supported by new model data. In comparison to
yesterdays damaging wind event, the tonight/tomorrow period of
strong winds is not as extreme and of the more typical terrain-
driven variety with widespread windy conditions but a shorter 2-4
hr window of peak gust speeds. However, yesterdays wind event may
have left some objects/infrastructure in a weakened state and
stronger winds tonight/early Friday may hamper ongoing recovery/repair
efforts. Hoenisch

&&

.AVIATION...
18/12Z TAF Period

VFR conditions prevail at TAF sites through tonight. Westerly flow
aloft strengthens again later today and tonight for increased
potential of mountain wave turbulence and instances of low level
wind shear. West to southwest Surface winds become gusty this
afternoon and evening at KCTB, KGTF and KEKS before
becoming more widespread to all terminals on Friday. Hoenisch

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  44  36  46  26 /  10  30  30  10
CTB  39  28  38  15 /  10  30  10   0
HLN  39  33  43  22 /  30  60  80  20
BZN  39  31  48  17 /  30  50  90  40
WYS  29  22  36   9 /  90  90 100  90
DLN  37  33  47  17 /  40  70  80  40
HVR  36  25  43   2 /   0  30  10   0
LWT  40  30  45  19 /  10  20  50  20

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from 2 PM this afternoon to 6 PM MST
Friday for East Glacier Park Region-Southern Rocky Mountain
Front.

High Wind Watch from this evening through Friday afternoon for
East Glacier Park Region-Eastern Glacier, Western Toole, and
Central Pondera-Northern High Plains-Southern High Plains-
Southern Rocky Mountain Front.

High Wind Watch from late tonight through Friday afternoon for
Cascade County below 5000ft-Eastern Pondera and Eastern Teton-
Eastern Toole and Liberty-Judith Basin County and Judith Gap-
Little Belt and Highwood Mountains.

Winter Weather Advisory from 6 PM this evening to midnight MST
Friday night for Gallatin and Madison County Mountains and
Centennial Mountains.

High Wind Watch from this evening through Friday afternoon for
Madison River Valley.

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

&&

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