Lewistown, Montana 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

786
FXUS65 KTFX 251221
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
521 AM MST Thu Dec 25 2025

Aviation Section Updated.

.KEY MESSAGES...

- Wintry mixed precipitation and freezing rain ends in a southwest
  to northeast fashion this morning.

- Temperatures will be mild for most for the next couple of
  days, although colder air will linger along the Hi-Line.

- Another weather system and attendant cold front will bring a period
  of areawide light snow and and much colder temperatures late
  Friday into Saturday.

- Temperature will trend near to above average for most locations
  heading into early next week, but the colder air will linger
  along the Hi-Line and over the southwest valleys.

&&

.UPDATE...

One more wave of freezing rain is currently moving eastward
through the plains where severe driving conditions are still being
observed from the previous round. The winter weather advisory was
extending through 9 am for all areas except the E Glacier/W Toole
zone. Temperatures will warm and precipitation will end from southwest
to northeast through mid- morning. - RCG

&&

.DISCUSSION...
/Issued 359 AM MST Thu Dec 25 2025/

 - Meteorological Overview:

An additional round of mixed precipitation and freezing rain will
continue to move east and northeast over the plains for next few
hours with the Arctic air retreating north as the precipitation
ends later this morning. Mild and breezy to windy conditions
generally prevail for the next day or so with a weak shortwave
bringing more mountain snow tonight into Friday.

The next system arrives late Friday into Saturday and will be
stronger and colder than previous ones with H700/H500 temperatures
falling to -15C/-30C near its axis. This will result in more
substantial mountain snow and even lower elevation light snow
during the frontal passage. This upper level support will send the
Arctic boundary all the way into southwest MT, at least briefly.

A Northwesterly flow aloft will set up heading into early next
week while high pressure builds to our west. Milder and breezy
conditions look to return for most locations, but the colder air
may be reluctant to leave the normally colder river/wind protected
valleys of north-central and southwest MT. - RCG

 - Forecast Confidence & Scenarios:

Freezing rain, drizzle, and patchy fog diminishes and improves
from southwest to northeast this morning...

The main area of freezing rain has crossed the Canadian border
leaving a widespread coating of ice generally ranging from trace
amounts to around 0.05 inches. Despite the low precipitation
amounts, the impacts to roads have been rather significant with
severe driving conditions and scattered road incidences being
reported between Dearborn and Havre and then in the Choteau area.
Another wave of freezing rain will move through between now and
mid-morning and bring an additional few hundredths of an inch of
incing. The latest hires guidance shows the last of the freezing
rain exiting the Hi-Line around 9 to 10 AM. The winter weather
advisory was extended for this area while the remainder advisory
area to the south and west tentatively looks ok to expire at 5 am
with lighter precipitation and warmer air poised to move in from
the southwest.

Mostly mountain snow and winds tonight through Saturday...

A weak shortwave will bring a round of mountain snow tonight into
Friday, mostly impacting the Northern Rocky Mountain Front and
the southern portion of the Madison and Gallatin mountain ranges.
The latter will have the best chance (50 to 80%) for 3 inches of
snow or more.

The stronger and colder trough will arrive late Friday into
Saturday and will deliver a more widespread snowfall. Snow will
again be heaviest in the mountains, especially along the Rocky
Mountain Front where Marias Pass stands around a 50% chance for 6
inches of snow or more. With an Arctic airmass finally being able
to clear the entire forecast area on Saturday, most lower
elevation look to see amounts ranging from a trace up to a couple
of inches. Winds don`t look overly impressive with either of the
aforementioned systems, but locations along the Rocky Mountain
Front look to see wind gusts over 60 mph at times on Friday. - RCG

&&

.AVIATION...
25/12Z TAF Period

Mixed precipitation and freezing rain over the plains will
diminish and end from southwest to northeast through 25/16Z.
Mostly VFR conditions then prevail, but low stratus and patchy fog
will continue to impact KHVR today and tonight. In fact there is
a 30% chance for fog redeveloping and reducing visibility below a
half mile after 26/00Z. Another shortwave will bring another wave
of scattered rain and snow tonight, mostly impacting areas along
the Continental Divide and southwest MT. - RCG

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  50  34  50   9 /  40  10  10  20
CTB  42  24  38  -2 /  30   0  10  30
HLN  48  31  46  22 /  20  30  30  50
BZN  50  32  49  23 /  30  30  40  30
WYS  40  28  36  18 /  70  90 100  70
DLN  49  31  44  24 /  20  30  30  20
HVR  30  23  38   3 /  70  10  20  20
LWT  52  35  50  13 /  20  10  10  20

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 9 AM MST this morning for Bears
Paw Mountains and Southern Blaine-Cascade County below 5000ft-
Eastern Pondera and Eastern Teton-Eastern Toole and Liberty-
Gates of the Mountains-Hill County-Northern Blaine County-
Southern High Plains-Western and Central Chouteau County.

Dense Fog Advisory until 9 AM MST this morning for Fergus County
below 4500ft-Western and Central Chouteau County.

&&

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