750
FXUS65 KTFX 122318
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
518 PM MDT Sat Sep 12 2026

Aviation Section Updated.

.KEY MESSAGES...

 - This afternoon it will be cool with isolated showers along the
   Hi-Line.

 - On Sunday there will be snow along the Rocky Mountain Front
   with isolated rain showers/thunderstorms across the rest of
   North-central Montana.

 - On Sunday it will be windy across the north-south orientated
   valleys of Southwestern Montana.

 - On Monday precipitation will linger with windy conditions
   across the plains of North-central Montana.

&&

.DISCUSSION...
/Issued 230 PM MDT Sat Sep 12 2026/

 - Meteorological Overview:

This afternoon an upper-level ridge builds in briefly over North-
central, Central, and Southwestern Montana. This will bring mostly
dry weather with status quo temperatures to the area. Along the
Rocky Mountain Front this afternoon there will be snow mixed with
rain at times and primarily all rain at lower elevations. This
afternoon/evening there will be isolated rain showers along the Hi-
Line. On Sunday a closed upper-level low will move over North-
central, Central, and Southwestern Montana with a 700mb low moving
over southern Alberta. This will bring strong southerly flow aloft
which will bring strong winds to north-south orientated valleys
of Southwestern Montana. On Sunday along the higher peaks of the
Rocky Mountain Front there will be snow with the rest of the
Rocky Mountain Front seeing rain and/or a rain/snow mix. On Sunday
across the rest of North-central Montana a frontal boundary will
move from west to east and bring rain showers with embedded
thunderstorms. Some of these rain showers/any thunderstorms have
the potential to produce gusty winds. See the Forecast Confidence
& Scenarios section for details. On Sunday warm air advection will
bring seasonable temperatures to Southwestern Montana with near
normal temperatures north of the I-90 corridor.

On Monday the upper-level low exits North-central, Central, and
Southwestern Montana. Precipitation will linger across North-central
Montana on Monday. On Monday low-level winds will increase which
will bring at least breezy conditions to North-central Montana. On
Monday temperatures will remain cool. Tuesday through Thursday
zonal flow with shortwave troughs moving through will affect
North-central, Central, and Southwestern Montana. This will allow
temperatures to be slightly below seasonal averages with isolated
showers around. On Friday an upper-level ridge moves over North-
central, Central, and Southwestern Montana. This will bring above
normal temperatures with dry weather to the area. -IG

 - Forecast Confidence & Scenarios:

On Sunday there is a 40 - 60% chance for sustained winds of 40 mph
or greater and a 20 to 50% chance for wind gusts of 55 mph or
greater in the Madison River Valley. As a result a High Wind Watch
remains in effect for the Madison River Valley from 12 PM to 9
PM. On Sunday there is greater than a 50% chance for 55 mph wind
gusts along the ridgetops of the Madison and Gallatin Mountains.
On Monday there is around a 50% chance for wind gusts of 55 mph
or greater across Judith Basin and Fergus Counties. Due to a lack
of 700 mb support for strong winds for Judith Basin County, a
High Wind Watch was only issued for Fergus County from 9 AM to 6
PM on Monday.

There is a 50 - 80% chance for a tenth of an inch of snow or
greater along the majority of the Rocky Mountain Front Sunday into
Monday. There is currently a low chance that isolated mountain
peaks will receive in excess of 3 inches of snowfall. Sunday into
Monday there is a 30 - 60% chance for a quarter inch of
precipitation or greater across North-central Montana. Sunday
evening a line of showers will move through North-central Montana.
As this line moves east of US Highway 87 between Great Falls and
Havre there is a low chance for an embedded thunderstorm to
produce gusty to strong winds. If temperatures continue to trend
upward on Sunday that will increase the instability and lead to a
greater risk for a thunderstorm to produce gusty to strong winds.
On Tuesday morning there is a 30 - 60% chance for low temperatures
of 36 degrees or colder across the valleys of Southwestern
Montana. -IG

&&

.AVIATION...
13/00Z TAF Period.

The primary concern tonight through Sunday morning will be low
stratus and even some patchy fog along the Rocky Mountain Front and
over/near the central island ranges. Other than KCTB being impacted
with a period of degraded cigs Sunday morning, mountain obscuration
over the aforementioned areas will be the primary impact. Then a mid
level closed low pressure system approaches the Northern Rockies on
Sunday and brings gusty south/southwesterly winds to southwest MT.
Farther north, easterly winds will gust over 25 kts at times at
KHVR. There will also be scattered showers and a few thunderstorms
on Sunday, mainly over central/North-central MT between 13/20 and
14/06Z. Low VFR/MVFR conditions and localized wind gusts over 35 kts
will be the primary concerns. - RCG

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  42  68  46  63 /   0  20  50  10
CTB  38  57  41  57 /   0  40  30  30
HLN  43  71  44  63 /   0  30  40   0
BZN  41  78  40  64 /   0   0  50  10
WYS  36  70  26  60 /   0   0   0   0
DLN  41  76  37  65 /   0   0   0   0
HVR  38  71  45  62 /   0   0  90  50
LWT  39  72  43  59 /   0   0  60  20

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
High Wind Watch from Monday morning through Monday afternoon for
Fergus County below 4500ft-Snowy and Judith Mountains.

High Wind Watch from Sunday afternoon through Sunday evening for
Madison River Valley.

&&

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