171
FXUS65 KTFX 092353
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
453 PM MST Tue Dec 9 2025

Aviation Section Updated.

.KEY MESSAGES...

- Gusty winds continue through the afternoon today.

- Another round of strong winds Wednesday for mainly the Rocky
  Mountain Front, with gusty winds still across the plains.

- Another round of rain and snow Wednesday, with better chances
  of accumulating snow at lower elevations Thursday through
  Saturday morning.

- Temperatures rapidly drop below freezing behind an arctic front
  Thursday.

&&

.DISCUSSION...
/Issued 302 PM MST Tue Dec 9 2025/

 - Meteorological Overview:

A low pressure system will continue to bring lower elevation
rain/snow and mountain snow this afternoon. The mid level jet will
continue to move out of the region this afternoon, which will help
decrease gusty to strong winds this evening.

Another upper-level disturbance arrives Wednesday and a warm front
lifts north Wednesday morning. This will bring more of a wintry mix
at lower elevations, transitioning to snow to rain. There is a
shallow enough warm nose along the warm front that there is a low
chance for a window of an hour of light freezing rain during the
transition along the Hi-line. A strong mid level jet moves in
Wednesday along the Rocky Mountain Front, which will bring strong
winds to the area. This mid level jet extending out farther east
across the North-Central MT plains will bring gusty winds throughout
the day.

Thursday through early Saturday morning, better chances for
accumulating snow at lower elevations arrives along an an arctic
front passing through the region Thursday. Temperatures quickly
dropping behind the front Thursday will likely cause a flash
freeze on roads. The front is expected to stall out somewhere
across North- Central MT Thursday night through Friday. Another
wave of Pacific moisture moves in Friday, which will keep periods
of moderate to heavier snow around North-Central MT through
Saturday. -Wilson

Over the weekend and into early next week, the forecast models
want the cold air to retreat back into Canada very quickly.
Sometimes this is too quick, but if southerly winds are strong
enough, it is possible for the cold air to move back north rather
quickly. -Brusda

 - Forecast Confidence & Scenarios:

Winds Wednesday:

Hi-res guidance showing a mid level jet approaching 85kts at times
along the Rocky Mountain Front during peak vertical mixing (late
morning to early afternoon). This brings good confidence for strong
winds along the Rocky Mountain Front to upgrade to a High Wind
Warning. With the mid-level jet still strong extending further
east, a few other areas across the North-Central MT plains will
try to produce strong winds as well. However, with a 50% or less
chance of 58mph wind gusts, they were left out of the warning at
this time.

Snow Thursday/Friday:

Confidence is increasing for impactful snow across the North-
Central plains. There are still some timing differences in when
and where the heavier snowfall occurs. Guidance now has flopped to
Friday having the moderate to heavier snow band set up across the
North- Central MT plains with additional Pacific moisture
advecting in. However, strong cold air advection long the arctic
front Thursday will crash road temperatures behind the front.
Frontogenetic banding along the front will bring a moderate band
of snow. With that, I decided to start the Winter Storm Watch
based on when the flash freeze will happen for the start time
Thursday. Timing will be ironed out better as models start to come
into better agreement in the coming days. - Wilson

&&

.AVIATION...
10/00Z TAF Period

The initial concern this TAF period will be for a wave of
rain and snow beginning late evening, lasting into early
Wednesday. The precipitation does linger into the afternoon across
eastern areas on the plains. Mountains will be obscured at times
from this precipitation, with the most sustained periods of
mountain obscuration along the Continental Divide.

Attention then turns to increasing surface winds speeds and gusts
along the Rocky Mountain Front and adjacent plains during the day
Wednesday. Instances of LLWS will exist prior to surface winds
increasing Wednesday. Mountain wave turbulence will become
increasingly common through the day Wednesday. -AM

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  31  55  44  53 /  40  50  40  80
CTB  25  47  23  39 /  60  50  50  70
HLN  32  53  45  52 /  60  70  30  60
BZN  30  53  41  53 /  60  40  10  30
WYS  24  40  29  39 /  80  80  20  30
DLN  32  53  39  53 /  60  10   0  10
HVR  20  44  25  35 /  20  70  70  80
LWT  24  48  37  49 /  30  90  40  80

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from midnight tonight to 11 AM MST
Wednesday for East Glacier Park Region-Southern Rocky Mountain
Front.

High Wind Warning from 8 AM to 8 PM MST Wednesday for Eastern
Glacier, Western Toole, and Central Pondera-Northern High Plains-
Southern High Plains.

Winter Storm Watch from Thursday morning through late Friday
night for Bears Paw Mountains and Southern Blaine-Eastern
Glacier, Western Toole, and Central Pondera-Eastern Toole and
Liberty-Hill County-Northern Blaine County.

Winter Storm Watch from Thursday afternoon through late Friday
night for Cascade County below 5000ft-East Glacier Park Region-
Eastern Pondera and Eastern Teton-Fergus County below 4500ft-
Judith Basin County and Judith Gap-Little Belt and Highwood
Mountains-Northern High Plains-Snowy and Judith Mountains-
Southern High Plains-Southern Rocky Mountain Front-Western and
Central Chouteau County.

&&

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