Big Sky Resort

000
FXUS65 KTFX 301753
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
1153 AM MDT Fri Oct 30 2026

Aviation Section Updated.

.KEY MESSAGES...

- Periods of dense fog and even some isolated instances of
  freezing drizzle will continue over the next 24 hours, most 
  widespread over central and north-central Montana.

- Precipitation becomes more widespread by Saturday night thru 
  early Monday, with accumulating snow most prevalent over the 
  higher terrain of southwest Montana.

- Below average temperatures trend closer to average next week.

&&

.DISCUSSION...
/Issued 518 AM MDT Fri Oct 30 2026/ 

 - Meteorological Overview:

Low level easterly flow will continue to bring low stratus and 
patchy fog for the next 24 to 36 hours, most widespread over 
central and north-central Montana. Meanwhile, a closed mid- level 
low churning over the Pacific NW will maintain a moist 
southwesterly flow aloft over the Northern Rockies and will send 
waves of spotty light precipitation over the forecast area, 
including isolated instances of freezing drizzle. The colder 
central/north-central areas and the high valleys along the 
MT/ID/WY borders will be most susceptible to trace amounts up to a
few hundredths of an inch of ice accumulation. 

The closed low will begin migrating towards the Northern Rockies 
Saturday night into Sunday. This system will be undergoing 
shearing and weakening, but will still bring a period of 
widespread precipitation Saturday night through early Monday. Most
of the lower elevation precipitation will fall in liquid form 
Saturday night and most of Sunday, but there may be some lingering
colder air for some light freezing drizzle, again mostly along 
the Hi-Line and the colder higher valleys of far southwest MT. 
H700 temperatures fall to around -5C by Sunday night and will 
bring more efficient accumulating snow over the higher terrain of 
the southwest. Colder northerly flow may also bring snow over the 
central island ranges, especially if a smaller scale vorticity max
helps enhance the precipitation as some deterministic models are 
now highlighting. 

Ensembles then favor ridging aloft to bring drier conditions and 
near average temperatures for much of the upcoming workweek. 
Westerly flow does increase some, but surface winds dont look to 
be much of a concern other than some breeziness along the Rocky 
Mountain Front and the nearby plains. - RCG

 - Forecast Confidence & Scenarios:

...Periods of dense fog through at least Saturday morning...

The cool and damp low level easterly flow will maintain nearly 
saturated surface conditions over central and north-central MT for
the next 24 to 36 hours. The dense fog advisory was expanded to 
include the lower elevations of Judith Basin county and all of 
Fergus, with visibilities trending below the half mile mark. 
Conditions will marginally improve during the day today, but 
continued moist easterly flow looks to bring another round of fog 
tonight into Saturday morning. Most hires models highlight even 
more widespread fog than the previous couple of nights. Again 
central and north-central locations will see the worst conditions,
but some southwest valleys also look to see more instances of fog
tonight into Saturday morning. Impacts will mostly be directly 
related from the reduced visibility, but frost deposition and even
some freezing drizzle may cause some slippery spots to develop on
area roadways, particularly the more susceptible bridges and 
elevated surfaces. 

...Light mountain snow and lower elevation rain, snow, and some 
mixed precipitation Saturday night through Monday morning...

The main trough moves through Saturday night through early Monday
and brings widespread precipitation to much of the forecast area.
The overall pattern and NBM probabilities favor the southwest 
mountains south of I90 for the best chance (60 to 80%) for 
snowfall amounts in excess of 3 inches. The higher terrain along 
the Continental Divide and the central island ranges will see some
snow, but higher totals will be contingent on local vorticity 
maximums and northerly flow enhancing the precipitation, which is 
not looking to be fully aligned with the moisture. A thin cold 
layer may also encourage some spotty freezing drizzle to develop 
along the Hi-Line and over some of the higher valleys along the 
MT/ID/WY borders Saturday night into Sunday morning, but impacts 
appear to be limited at this time. - RCG 

&&

.AVIATION...
30/18Z TAF Period 

Continued LIFR and IFR conditions for the northern tier terminals
as well as KBZN with low stratus, patchy fog, and mist. Localized
areas of freezing drizzle is possible today and into tomorrow 
morning for Central MT north of KLWT and North Central MT along 
the Rocky Mountain Front. Primary hazards will be moderate icing 
and widespead visibility restricitons and mountain obscurations.
MVFR to VFR conditions are expected to return tomorrow after 18Z
for most terminals. - Akins

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  30  52  35  46 /  10  20  20  70 
CTB  26  50  29  44 /  20  10  10  60 
HLN  31  50  34  46 /  10  30  20  80 
BZN  30  48  32  45 /  10  20  10  50 
WYS  26  45  26  44 /  50  70  60  90 
DLN  33  48  34  43 /  20  30  40  90 
HVR  26  50  29  52 /   0  10  10  40 
LWT  29  53  33  53 /  10  20   0  30 

&&

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

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