797
FXUS65 KTFX 042005
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
205 PM MDT Sat Oct 4 2025

.KEY MESSAGES...

 - A low pressure system moves through the region this weekend
   and brings progressively cooler temperatures and lowering snow
   levels.

 - Impactful snowfall will remain mostly in the mountains tonight
   into Sunday with some brief wet snow at lower elevations
   Sunday morning.

 - Gusty northerly winds and much colder temperatures Sunday will
   be followed by a widespread hard freeze at many locations
   Sunday night.

 - Milder and drier conditions return early next week.

&&

.DISCUSSION...

 - Meteorological Overview:

Showers and mountain snow are continuing to increase this
afternoon before a quick moving trough and attendant cold front
brings gusty northerly winds, much cooler temperatures, and the
first widespread mountain snowfall of this young fall season.
Multiple circulations will be either splitting off or merging with
the main trough as it dives southeastward, adding some
uncertainty to some of specific evolution of the heaviest
rain/snow, though the general expectations have not changed much
over the last 24 hours.

Cold north to northeasterly upslope flow moves into the Northern
Rocky Mountain Front area tonight with H700 temperatures falling
to as low as -20C. Snow will increase in the Glacier National Park
area by midnight before sliding southward and impacting the
Southern Rocky Mountain Front, the adjacent plains west of I15,
and the central island ranges and their northerly upslope areas by
Sunday morning. The core of the rain and snow then moves into the
southwest later Sunday morning and afternoon. The snow will be
wet and may become heavy for a period, especially along the Rocky
Mountain Front and nearby high plains. Northerly winds generally
gusting in the 15 to 30 mph range will accompany the snow while
temperatures dip into the upper 20s to middle 30s.

Precipitation ends from north to south during the day on Sunday
as the trough quickly exits the region. Partial clearing of skies
and light winds will result in the first widespread lower
elevation freeze of the season Sunday night into Monday morning.
After some moderation in temperatures Monday afternoon, another
cold night is expected for most locations Monday night into
Tuesday.

Most ensembles favor ridging aloft to bring a return to above
average temperatures and drier conditions for much of next week,
despite a weak closed low brushing southwest MT Tuesday into
Wednesday and a southeasterly moving shortwave and weak cold front
passing through the plains Wednesday into Thursday. Another
trough is then expected to bring more unsettled conditions
sometime next weekend, though there are plenty of disagreements
among ensembles to sort out. - RCG

 - Forecast Confidence & Scenarios:

Snow and gusty northerly winds along the Rocky Mountain Front and
North-central Montana tonight and Sunday...

The greatest impacts are expected over the north to northeasterly
upslope areas along the Rocky Mountain Front and the adjacent
high plains followed by areas along and north of the central
island ranges. There will be sufficient saturation in the
dendritic growth zone to support a 3 to 6 hour opportunity for
snowfall rates to exceed 1 inch per hour in the Glacier National
Park area and foothills to the east. H700 temperatures bottoming
out near -20C will ensure snow levels drop to the surface of the
plains, bringing at least some accumulating snow to the plains
west of I15 and areas from along the highway 200/87 from Rogers
pass to around the Geyser area. The probabilities for snowfall
totals over 3 inches have increased to over 90% for most of the
higher terrain the Rocky Mountain Front with around a 60% chance
for Marias Pass. There is also a 60% chance for 3 inches of snow
or more for Roger`s Pass and King`s Hill Pass. Most plains
locations have less than a 20% chance for 3 inches of snow or more
with the exception of areas along Duck Lake Rd north of browning
where there is around a 50% chance.

Northerly winds gusting over 30 mph at times will combine with
the wet snow and create dangerous outdoor conditions for those
outdoors in the backcountry, including increased risk for
hypothermia and frost bite. Forest roads may become very difficult
to travel or impassible. Areas that receive heavy wet snow will
be susceptible to power outages and other infrastructure
disruptions. Peak timing for impacts will be from midnight to 8 am
along the Rocky Mountain Front and between 4 AM and noon for the
Southern Rocky Mountain Front and the central island ranges. The
only change to the winter products was to add the southern high
plains zone to the winter weather advisory.

Snow and gusty northerly winds over Central and Southwest Montana
tonight and Sunday...

The heaviest snowfall for central and southwestern areas will be
Sunday morning morning and afternoon. The Madison and Gallatin
mountain ranges are still expected to see the most snowfall and
impacts, but deterministic guidance has have recently increased
snowfall for areas along the Continental Divide as well. The
probability for 3 inches of snow or more remain around 60 to 80%
for areas above 7,000 feet in the Gallatin/Madison mountains.
Lower elevation snow can also be expected down here as well, but
accumulations should be negligible, especially with much of the
snow falling during the day. Northerly winds will gust over 30 mph
at times here, mostly for the north to south oriented valleys.
Impacts will mostly be limited to outdoor recreationists where
there will be a hypothermia risk to those not properly dressed and
difficult to impassible travel conditions on area forest roads. A
winter winter advisory was added for the Big Hole and Chief
Joseph Pass areas; otherwise, no changes were made to the current
winter weather highlights already in place. - RCG

&&

.AVIATION...
04/18Z TAF Period

VFR conditions will prevail across the KHVR terminal during this TAF
Period. During the majority of this TAF Period rain will affect all
of the terminals except for KHVR terminal. This rain will reduce
visibility and ceilings to a least MVFR levels during a portion of
this TAF Period. During the last 6 hours at all terminals except for
the KBZN and KHVR terminals snow will mix in with the rain with no
runway accumulation expected. There will be gusty winds at all
terminals towards the end of this TAF Period. There will be mountain
obscuration during the duration of this TAF Period. -IG


&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  32  46  27  60 /  90  90   0   0
CTB  30  44  22  58 /  90  70   0   0
HLN  35  45  27  58 /  90  90   0   0
BZN  35  46  26  54 /  80  90  10   0
WYS  27  45  18  52 /  80  80  30   0
DLN  33  46  24  54 /  60  60   0   0
HVR  34  51  26  62 /  30  20   0   0
LWT  34  45  24  57 /  80  50  10   0

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning from midnight tonight to noon MDT Sunday
for East Glacier Park Region.

Winter Weather Advisory from midnight tonight to noon MDT Sunday
for Little Belt and Highwood Mountains-Northern High Plains-
Snowy and Judith Mountains-Southern High Plains-Southern Rocky
Mountain Front.

Winter Weather Advisory from 6 PM this evening to 6 PM MDT
Sunday for Gallatin and Madison County Mountains and Centennial
Mountains.

&&

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