Shelby, Montana 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

898
FXUS65 KTFX 232058
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
158 PM MST Tue Dec 23 2025

.KEY MESSAGES...

 - Freezing rain and drizzle across portions of the Hi-Line this evening
   into early Wednesday, with areas of fog also developing.

 - Another round of freezing rain over portions of the plains late Wednesday
   evening into Thursday morning, with largely light mountain
   snow occurring over the same timeframe.

 - A Canadian cold front moves south over the plains into some Central
   Montana valleys Friday night into Saturday, bringing at least
   briefly colder temperatures and an opportunity for lower
   elevation snow.

&&

.DISCUSSION...

 - Meteorological Overview:

Southwesterly flow aloft is in place across the region ahead of
upstream troughing off the Pacific coast. At the surface a cooler
airmass is in place over portions of the plains, with more mild
temperatures further south/west. Weak forcing moving through the
southwesterly flow aloft late this afternoon and evening will result
in light precipitation developing over the plains, largely across
the Hi-Line and adjacent areas. The cooler air remaining at the
surface combined with warmer air aloft will result in a period of
freezing rain this evening before precipitation lifts north of the
border tonight. Lingering easterly upslope flow near the surface
will result in either freezing drizzle or fog tonight across similar
areas near the Hi-Line. Given the combination of freezing rain and
the potential for freezing drizzle has resulted in a Winter Weather
Advisory being issued for these areas. Slick roads are forecast to
develop, which result in difficult travel conditions. Low clouds and
or fog linger into the day Wednesday over the plains, resulting in a
cooler day.

Further southwest across Southwest Montana valleys, the remainder of
the day today and into most of tomorrow remains dry. The main impact
will be from increasing southerly winds through the day Wednesday as
the pressure gradient increases. North south oriented valleys will
see the most potent winds, with the Madison River Valley favored for
the strongest winds. A High Wind Warning has been issued for this
area.

As the aforementioned Pacific troughing nudges eastward toward the
Western US coastline, another wave ejects toward the Northern
Rockies Wednesday evening into Christmas day. This wave looks more
potent and will result in a frontogenetic band of precipitation
developing, oriented from southwest to northeast. Mountain snow will
fall at times, with high peaks near the Idaho border most favored
for accumulating snow Christmas day. The greater impact looks to be
from freezing rain however, which develops over portions of the
plains Wednesday night into Christmas morning. Icy roads are
forecast to develop where this freezing rain ultimately develops,
which is most favored in the Golden Triangle and points eastward.
There remains uncertainty with respect to surface temperatures on
the southern portions of the plains, which makes it difficult to pin
down the exact extent of freezing rain at this time horizon. Given
this is the case, no Winter Weather Advisories are being issued at
this time for this timeframe. Should confidence in location of
freezing rain increase, Winter Weather Advisories would become
necessary.

Additional weaker waves move across the Northern Rockies on Friday
from the Pacific troughing, which will result in light, mainly
mountain snow at times into Friday night. Thereafter a more potent
wave diving southeastward from BC looks to propel a Canadian cold
front across the plains and into some Central and Southwest MT
valleys Friday night into Saturday. Pacific moisture overrunning
this colder airmass will result in some lower elevation snow Friday
night into early Saturday.

The region looks largely dry thereafter into early next week, with
the greatest uncertainty associated with just how quickly the colder
surface airmass over the plains moves out. Areas in and near the
Milk River valley will need an extra day to see the cold air move
out compared to most other areas over the plains. -AM


 - Forecast Confidence & Scenarios:

Freezing rain and drizzle tonight:

High resolution guidance as well as some other guidance is wringing
out just enough moisture across portions of the Hi-Line this evening
to result in a glaze of freezing rain. The precipitation moves north
of the border after midnight, though lingering low clouds will
result in either fog or some freezing drizzle. Given the risk for
freezing drizzle extends into at least the early morning Wednesday,
the Winter Weather advisory extends through this timeframe. Should
the drizzle not materialize, fog would be favored, and would result
in visibility reduction heading into the day Wednesday.

Freezing Rain Wednesday night into Christmas:

The aforementioned frontogenetic band of precipitation looks to
develop Wednesday evening into Wednesday night, shifting
northeastward across the plains into Christmas. There remains some
uncertainty in the exact track of this band, with additional
uncertainty related exactly how far south the colder surface air
mass is able to make it by the time precipitation starts. Should the
colder air struggle to make inroads further south, the risk for
freezing rain would be in a rather narrow corridor. Conversely,
should the colder air make it all the way to Great Falls and
Lewistown, a more widespread risk for freezing rain would develop
Wednesday night into Christmas Day. These trends will be monitored
closely over the next day or so.

Canadian cold front this weekend:

A push of much colder looks to arrive late Friday night into
Saturday. The probability for a high of 10 F or less across the Hi-
Line Saturday is greater than 50%. Although snow will accompany this
push of colder air, the probability for snow in excess of an inch at
lower elevations on the plains is at or below 20% Friday night into
Saturday. -AM

&&

.AVIATION...
23/18Z TAF Period

Main concern will be the potential for freezing rain later this
afternoon and into this evening. Light precipitation currently
falling west of the divide will move northeast into Northeast MT
by evening. It is likely that surface temperatures will remain
below freezing in the Havre area, thus the higher chances for
freezing rain. After the freezing rain exits, a light freezing
fog will develop over portions of North Central MT as well.
Another round of mixed precipitation is looking likely over much
of North Central and Southwest MT Wed afternoon/evening.
Mountains/passes will be obscured at times across the period.
Brusda

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  20  30  20  45 /  20   0  50  30
CTB  16  19  11  38 /  20   0  10  10
HLN  30  50  36  49 /  20   0  70  30
BZN  31  53  40  49 /  10  10  70  50
WYS  29  41  36  39 /  10  60 100  90
DLN  27  50  38  45 /  10  20  80  30
HVR  17  28  20  31 /  30   0  30  30
LWT  37  55  33  46 /  10   0  40  30

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 9 AM MST Wednesday for Eastern
Toole and Liberty-Hill County-Northern Blaine County.

High Wind Warning from 6 AM to 8 PM MST Wednesday for Madison
River Valley.

&&

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