013
FXUS65 KTFX 250951
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
251 AM MST Tue Nov 25 2025

.KEY MESSAGES...

 - After relatively dry conditions during the day today another
   wave of light snow is expected to return tonight and into the
   day on Wednesday across Southwest and Central Montana.

 - Better chances for impactful snow arrive on Thanksgiving across
   Central and North Central Montana, with snow lingering through
   the day on Friday as a strong cold front moves south through
   Montana.

 - Coldest air of the season so far will arrive this weekend.

&&

.DISCUSSION...

 - Meteorological Overview:

Relatively dry condtions are expected through the daylight hours
today beneath northwesterly flow aloft in wake of the departing
disturbance; however, isolated snow shower can`t be ruled out over
and near the mountains north of the US Hwy 12 corridor. Temperatures
will be  some 5 to 15 degrees colder than that of Monday, with light
southerly winds. By this evening an embedded wave within the
northwest flow will quickly dive southeast from over British
Columbia and the Pacific Northwest and over Southwest and Central
Montana through Wednesday morning. This quick moving wave will bring
light snowfall to the valleys of Southwest and Central Montana, with
generally 1-3" for the passes and upwards of 6" to the higher peaks.

On Thursday transient ridging ahead of a shortwave digging into the
Pacific Northwest will begin to slide towards the Northern Rockies,
with a mid-level warm front lifting from southwest to northeast over
Southwest through North Central Montana. Pacific moisture and lift
associated with the warm front will overrun the colder air near the
surface during the day Thursday, which will help to support a band
of snow lifting north across the Northern Rockies. This band of snow
looks to be "most" intense along and north of the Montana Hwy 200
corridor, but even areas northeast of a Helena to Bozeman line are
likely to see some snow. The aforementioned shortwave digging into
the Pacific Northwest will continue to dig southeast towards the
Central Rockies through Friday morning, with a strong cold front
surging south across Montana through the day on Friday. This cold
front and the upper level disturbance will bring additional
opportunities for snow to most locations across Southwest through
North Central Montana, especially to the plains of Central and North
Central Montana and northerly upslope areas of Southwest, Central,
and North Central Montana. Cold air will also filter south in wake
of the cold front bringing the coldest air of the season so far for
the weekend. - Moldan

 - Forecast Confidence & Scenarios:

Accumulating Snow from late tonight through Wednesday...

A fast moving disturbance within northwest flow will bring a quick 1-
3" of snow to mountain passes along and south of the Montana Hwy 200
corridor and north of a Chief Joseph to West Yellowstone line, and 3-
6" to the higher peaks. Most valley locations are likely to see less
than 1" of snow, with the exception of the eastern Gallatin Valley
(i.e. western/northern foothills of the Bridger and Gallatin Ranges)
where HREF probabilities support a 60+% chance for 1" or more of
snow and a 20-40% chance for 2" or more snow. For now no Winter
Weather Advisories have been issued given the borderline amounts and
timing of the snow (i.e. 1/3rd of the snow will fall during the
lower traveled overnight hours tonight), but given that this is the
Thanksgiving travel week future shifts may consider highlights.

Accumulating Snow Thursday through Friday evening...

ECMWF EFIs with respect to snow, which signify the potential for a
climatologically unusual (values of between 0.5 to 0.8) or very
unusual to extreme (values of 0.8+) snow event, along and north of
the US Hwy 12 corridor remain (from the past 24 hours) in excess of
0.5 from the evening hours of Thanksgiving through the day on
Friday, with values now (latest) ranging between 0.6 to 0.7 over
much of the plains of Central and North Central Montana.
Additionally, NBM4.3 probabilities for 4" or more of snow over the
plains of Central and North Central Montana generally range from a
10-30% chance, which are relatively unchanged over the past 24
hours. Probabilities for 6" or more of snow over this same timeframe
range from a 30% chance across the Island Ranges of Central Montana
to between a 60-80% chance along the Continental Divide north of the
Montana Hwy 200 corridor, with a 30-50% chance for 12" or more of
snow across the same locations of the Continental Divide. Given that
the snow will begin falling during the day on Thursday and persist
into the day on Friday this event has the potential to disrupt a
busy time for holiday travel. What is becoming more concerning in
addition to the falling snow will be the potential for
blowing/drifting snow Thursday night through Friday morning along
and west of the I-15 corridor over the plains of Central and North
Central Montana. By Thursday evening a barrier jet, with H850 wind
speeds of 20-30kts, will begin to slide south along the Rocky
Mountain Front. These strong boundary layer winds combined with the
falling snow may present a scenario where significant reductions in
visibility occur for travelers on the US Hwy 89 and I-15 corridors
northwest/north of Great Falls. Future winter weather highlights
will be needed should trends hold.

Cold Temperatures Friday through Sunday...

Guidance is beginning to come into better agreement with the timing
of the cold air arriving to the Northern Rockies on Friday/Friday
night as an Arctic front dives south from Canada. What remains
unclear is how cold temperatures actually fall through the weekend,
which is mainly due to uncertainty on how much snow falls prior to
and with the passage of the cold front. Should most locations see
several inches of snowfall from Thursday through Friday then there
is a better chance for temperatures to be much colder than currently
forecasted. - Moldan


&&

.AVIATION...
25/06Z TAF Period

Snow is expected to diminish across the lower elevations by 25/08Z
with scattered mountain snow showers continuing through 25/12Z
before tapering off. Mountain obscuration will remain a concern
through the first 6 hours of the period. There is a chance for
fog developing overnight where clearing occurs, particularly at
KHVR, but at this time the probabilities are too low to include
it in the TAF.

After 25/12Z, low-level clouds will clear out and give way to mid
to high level clouds through most of the day before cloud cover
starts to increase in the afternoon past 26/00Z with the potential
for some lower ceilings that may reignite some concerns for
mountain obscuration through the remainder of the period.
-thor

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  36  26  39  25 /   0  20  30  10
CTB  31  15  33  16 /   0  10  20  10
HLN  33  25  37  28 /   0  40  50  20
BZN  33  22  38  25 /   0  50  70  20
WYS  27  14  31  19 /   0  60  90  30
DLN  33  23  42  27 /   0  20  20  10
HVR  29  11  27  10 /  20   0  10   0
LWT  34  19  34  22 /   0  10  30  10

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
None.
&&

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