707
FXUS65 KTFX 060034
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
534 PM MST Wed Feb 5 2025

Aviation Section Updated.

.KEY MESSAGES...

 - Not quite as cold late this week into the weekend.

 - Another round of snow late Thursday night into Friday, mostly
   across Southwest and Central Montana.

&&

.UPDATE...

Snow has moved out of the areas that previously had Winter Storm
Warnings and Winter Weather Advisories, so those were cancelled
earlier this afternoon. Temperatures at lower elevations have not
warmed up as previously forecast, as widespread breezy
southwesterly winds have not developed. Have therefore decreased
winds somewhat this evening to delay the onset of the winds, and
have lowered overnight lows to better reflect continued cooling
this evening before a gradual warmup overnight.

However, these winds will not really move into the Hi-Line area
overnight, so have lowered temperatures there. This has caused
overnight wind chills to lower to between -25F and -35F in Hill
and Blaine Counties, so have issued a Cold Air Advisory there
through Thursday morning. -Brusda/Coulston

&&

.DISCUSSION...
/Issued 154 PM MST Wed Feb 5 2025/

Main changes this afternoon have been to address the continuing
heavy snow in and around the Bozeman area, as westerly flow in
the wake of a surface trough upslopes in the Gallatin Valley.
Current satellite imagery does show some of the upper level and
convective clouds beginning to move eastward away from the area,
but some low level clouds do remain as of 2PM. Dry air will
gradually intrude into the valley later this afternoon/early this
evening, but until the dry air arrives expect snow to continue to
fall, with an additional inch possible in the valley and up to an
additional inch or two over the pass. Further south, a line of
intense snow showers will gradually move through Southern
Gallatin and Madison Counties through the evening, bringing some
tough travel conditions as it moves through. For more information
on the weather, see the previous discussion section below. Ludwig

 - Meteorological Overview:

Transitioning toward tonight, the arctic airmass in place
attempts to briefly pull northeastward over the plains. Breezy
winds may result in instances of blowing and drifting snow across
Southwest Montana, Judith Basin county, and along the Rocky
Mountain Front tonight into Thursday, but confidence in impacts
is too low at this time to justify a Winter Weather Advisory.

After a brief break Thursday the remnants of the upper level low
off the Pacific Northwest coastline shift eastward across the
Northern Rockies. This will result in another period of snow,
with accumulations most favored across Southwest and Central
Montana Thursday night through Friday.

A northwesterly flow aloft prevails in wake of the system Friday,
which will keep the region on the colder side of normal this
weekend into early next week. Guidance favors a few waves
traversing this upper level northwesterly flow over this
timeframe, which will keep low-end chances for snow in the
forecast. -AM

 - Forecast Confidence & Scenarios:

Blowing snow tonight into Thursday:

Winds have had a harder time mixing down into the valleys of
Southwest Montana than was previously forecast, thus limiting the
threat for widespread blowing snow there. However, winds in the
mountains have been quite gusty, making blowing snow there more
probable into the day on Thursday.

Next round of snow Thursday night into Friday:

Snow over this timeframe is most favored across Central and
Southwest Montana. Mountains in these areas largely have a
greater than 50% chance for 6 inches of snow, with around a 10%
chance for the same snow amount in Great Falls, Lewistown, and
Helena. Areas along and north of US-2 are not likely to see much,
if any snow with this system. -AM

&&

.AVIATION...
06/00Z TAF Period

VFR conditions are forecast to persist through at least 07/00Z
across most of North Central, Central, and Southwest Montana.
However, lingering snow showers along the Continental Divide will
cause some mountain obscuration there through 18Z, and the
passage of a disturbance may cause similar conditions in the
Central Montana mountains between 06Z and 18Z.

Otherwise, skies will remain mostly clear to partly cloudy through
the period, with the aforementioned disturbance bringing mostly
cloudy skies to the area between 06Z and 18Z.

Winds will be the main concern, as the moderate westerly flow
aloft will continue some mountain wave turbulence and low-level
wind shear until those winds decrease after 18Z or so. The main
trouble spot will be KEKS, as forecast models indicate that
southerly wind gusts could exceed 35 kt through around 12Z or so,
but the winds there have yet to translate down into the valley.
Will continue to monitor the situation there. -Coulston

Refer to weather.gov/zlc for more detailed regional aviation
weather and hazard information.

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  -7  17   3   9 /  10  10  30  80
CTB -10  14  -4  11 /   0   0   0  30
HLN  -2  26   8  13 /  10  10  40  80
BZN  -3  28  10  21 /  10  10  50  90
WYS   0  25  11  32 /  10  10  70 100
DLN   8  30  15  28 /   0  10  20  90
HVR -18   9 -10  10 /   0   0   0  40
LWT  -6  20   5  13 /  10  10  40  90

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
Cold Weather Advisory until 11 AM MST Thursday for Bears Paw
Mountains and Southern Blaine-Hill County-Northern Blaine County.

&&

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