998
FXUS65 KTFX 051538
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
938 AM MDT Sun Oct 5 2025

.KEY MESSAGES...

 - Much colder air surges south across the area today behind an
   early morning cold front with gusty north winds.

 - Accumulating snowfall will primarily occur in the mountains but
   some lower elevations areas will see a mix or change to snow
   this morning before precipitation ends from north to south this
   afternoon.

 - The first widespread hard freeze is expected tonight.

 - Warmer and drier conditions return for the week ahead.

&&

.UPDATE...

930AM: No significant changes were needed with the update this
morning. Winter Weather Advisories will remain in effect for the
time being, though some may ultimately be canceled early given
diminishing impacts.


645AM: Given impactful snow has subsided in northern areas, the
Winter Storm Warning for eastern Glacier NP region and Winter
Weather Advisory for the Northern High Plains has been canceled
early.

&&

.DISCUSSION...
/Issued 650 AM MDT Sun Oct 5 2025/

 - Meteorological Overview:

A fairly potent shortwave continues to drop south through the
Northern Rockies early this morning within the broader upper level
trough situated across the region. Height falls and cooling aloft
have already lowered snow levels across much of the area to
5500-6500 ft overnight with a significant push of lower level
cooling occurring as colder air surges south along the high plains
east of the Rockies in tandem with the shortwave dropping south
through western MT. Widespread precipitation occurring across
western portions of north-central and central MT early this
morning will shift southward through mid-day as the shortwave
rotates through the broader upper trough with precipitation ending
from north to south this afternoon. Heaviest snowfall will occur
across the mountains near the Rocky Mtn Front early this morning,
shifting south and east across the central and southwest MT
mountains later this morning with decreasing intensity.

Surface high pressure and the associated cold airmass slide south
across the area tonight behind the departing upper level trough.
Clearing skies, drier conditions and generally light winds will
set the stage for the coldest night of the season so far with most
locations expected to see temperatures fall to the mid-upper 20s
by early Monday morning. Temperatures rebound fairly quickly as
upper level ridding develops across the interior western US
through the first half of the upcoming week and potentially
amplifies later this week for additional warming. Confidence in
the overall pattern evolution decreases later this week into next
weekend as the next upper level approaches from the west.

 - Forecast Confidence & Scenarios:

The only change to ongoing winter weather statements was to add a
Winter Weather Advisory for the Upper Blackfoot/Macdonald pass
zone. Snow developed overnight at Flesher pass where road surface
data would support some slush accumulation possible. Areas from
Rogers Pass south through Flesher Pass and adjacent portions of
central/southern Lewis and Clark county will be in a favorable
position for enhanced snowfall in northerly upslope flow for
several hours early this morning. Similar conditions but less
intense snowfall is expected over MacDonald pass.

Snow levels fall to as low as around 3500 ft across western
portions of north-central MT early this morning with a mix or
change to wet snow likely across many areas along the I15
corridor, primarily north of Helena. While snow will likely not
impact roads or accumulate at elevations this low, it may bring a
period of lower visibility. Hoenisch

&&

.AVIATION...
05/12Z TAF Period

Widespread precipitation across western portions of north-
central/central MT early this morning will shift southward across
southwest MT before ending from north to south this afternoon.
MVFR/IFR conditions accompany the precipitation this morning with
low clouds maintaining some MVFR ceilings into early this
afternoon before clouds begin to clear from north to south later
this afternoon and evening. Snow levels lower enough to mix or
change precipitation to snow this morning, resulting in lower
visibility but unlikely to affect runway surfaces. Gusty north
winds continue through early this afternoon before diminishing
from north to south later this afternoon and evening. Hoenisch

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  44  27  59  33 /  90   0   0   0
CTB  43  23  58  31 /  40   0   0   0
HLN  44  27  58  32 /  90   0   0   0
BZN  44  26  55  26 /  80  10   0   0
WYS  44  17  51  16 /  70  20   0   0
DLN  47  25  55  28 /  60   0   0   0
HVR  51  26  62  32 /  30   0   0   0
LWT  43  26  58  31 /  70   0   0   0

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until noon MDT today for Little Belt and
Highwood Mountains-Northwest Beaverhead County-Snowy and Judith
Mountains-Southern High Plains-Southern Rocky Mountain Front-
Upper Blackfoot and MacDonald Pass.

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

&&

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