361
FXUS65 KTFX 310300
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
900 PM MDT Fri Oct 30 2026

.KEY MESSAGES...

- Areas of fog will redevelop across north-central MT tonight and
  may be locally dense with low visibility and some patchy icing
  of elevated surfaces.

- A Pacific weather system brings more widespread precipitation by
  Sunday with initially high snow levels eventually lowering to
  mountain passes late Sunday and Sunday night.

- Temperatures trend closer to average early next week.

&&

.UPDATE...

A Dense Fog Advisory has been issued for along the Rocky Mountain
Front as well as Judith Basin and Fergus county below 4.5kft
through 11 AM on Saturday. Widespread areas of patchy fog will
continue to develop and expand as weak southerly flow continues
to pump in moisture keeping the fog threat through early Saturday
morning. With temperatures near freezing, isolated slick spots are
possible especially along bridges. In addition to the fog, patchy
areas of drizzle will persist across the area, with more
persistent drizzle pushing through RMF and Hi-Line. Conditions
improve as we warm up Saturday especially as we move into the
afternoon hours.

&&

.DISCUSSION...
/Issued 522 PM MDT Fri Oct 30 2026/

 - Meteorological Overview:

Low clouds/stratus have spread into some SW MT valleys including
areas as far south as the Gallatin Valley and Norris Hill. These
areas may see some improvement through the rest of this afternoon
while light easterly surface winds across the north-central MT
plains will maintain widespread low clouds/stratus along with some
lingering areas of fog. Areas of fog will redevelop/expand again
tonight across the plains while increasing mid-high level clouds may
prevent widespread fog development overnight across southwest MT. A
more southerly flow aloft develops tonight ahead of an upper level
trough offshore of the Pacific NW with a few light showers
potentially tracking north into portions of SW MT and along the
Continental Divide after midnight.

Additional showers track northward into primarily areas near the ID
border through much of the day tomorrow as the offshore trough
elongates and shifts inland. More widespread precipitation develops
late Saturday night through Sunday as the trough axis shifts east
across the Rockies. The bulk of the energy tracks south of the area
with highest precip amounts expected across eastern portions of
southwest MT while a more brief period of precipitation shifts across
central/north-central MT, mainly late Sunday, before the trough
and associated precipitation shift east of the area on Monday.
Snow levels are initially above 7000 ft with models continuing to
trend slower with the arrival of cooling aloft and lowering snow
levels on Sunday, limiting impactful snowfall to areas mainly
above passes through much of the weekend.

Upper level ridging rebuilds early next week, but may be transient
with most model ensembles showing some form of undercutting energy
tracking east from the Pacific and inland by Wednesday.
Temperatures should rebound to closer to average for at least the
first part of next week. Hoenisch

 - Forecast Confidence & Scenarios:

Areas of dense fog are likely again tonight with with the
easterly/light-upslope flow supporting the highest risk (60-80%) for
visibility of 1/4 mile or less along areas adjacent to the east
slopes of the Rocky Mtn Front and Judith/Snowy Ranges. The influx
of mid-high level cloud cover from The south later tonight may
help mitigate a greater coverage of dense fog across north-central
MT.

Temperatures in the mid-upper 30s across the north-central MT
plains will fall to near or slightly below freezing again tonight,
bringing some risk for localized icing of elevated surfaces,
especially in areas where fog is most dense and may support
freezing drizzle. The shallow cool airmass continues to erode
Saturday and Sunday, but a few isolated locations may hold onto the
colder air as precipitation arrives Saturday night Sunday creating
some potential for light freezing rain/drizzle.

The risk for snow accumulation in excess of 2 inches late this
weekend is highest at elevations above 7000 ft but only around 20%
or less for most passes at or below 7000 ft. Hoenisch

&&

.AVIATION...
31/00Z TAF Period

IFR to LIFR conditions will continues across north and central
Montana through the night into Saturday morning. Widespread low
stratus deck with patchy drizzle will persist across much of the
area. Areas of dense fog are likely through the night, especially
across the northern Terminals. Temperatures will be hovering near
freezing, so localized freezing fog is possible. Mountain
obscuration will persist through the morning hours, improving
towards the end of the TAF period across all terminals.
Precipitation chances increased across Southwest Montana as an
upper-level trough pushes our next system in. -JR

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  30  50  35  44 /   0  20  10  70
CTB  27  50  29  45 /  20   0  20  60
HLN  31  50  35  45 /   0  20  20  80
BZN  31  47  33  43 /  10  40  10  60
WYS  28  43  28  40 /  70  80  70 100
DLN  35  48  37  42 /  20  60  60  90
HVR  26  47  29  50 /   0  10  10  10
LWT  27  48  33  52 /   0  20   0  20

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
Dense Fog Advisory until 11 AM MDT Saturday for Eastern Glacier,
Western Toole, and Central Pondera-Fergus County below 4500ft-
Judith Basin County and Judith Gap-Northern High Plains-Southern
High Plains.

&&

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