378
FXUS65 KTFX 301115
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
515 AM MDT Sun Aug 30 2026

Aviation Section Updated.

.KEY MESSAGES...

 - Gusty west winds develop from the late morning through evening
   hours.

 - Some minor snow accumulations are expected above 6500 feet
   across Glacier National Park.

 - High temperatures today will be 10 to 15 degrees below normal.

&&

.DISCUSSION...
/Issued 1203 AM MDT Sun Aug 30 2026/

 - Meteorological Overview:

Showers and thunderstorms will gradually exit to the east of the
Northern Rockies through the late morning and afternoon hours, with
increasing westerly winds replacing the departing precipitation for
the remainder of the day. High temperatures in wake a Pacific cold
front will only rise into the mid-50s to near 70 degrees today,
which is 10 to 15 degrees below normal. Falling snow levels along
the Continental Divide, specifically the Glacier National Park
region, is expected to lead to some minor snowfall accumulations
prior to precipitation ending.

Quasi-zonal flow to begin the work week will back to the southwest
through the day on Tuesday as upper level troughing digs south along
the western seaboard. This trough will deepen through the middle of
the work week while slowly drifting east over the Western CONUS,
which will place the Northern Rockies beneath southwest to southerly
flow through the remainder of the forecast period. Pacific moisture
streaming northeast to north within this flow will support daily
chances for showers and storms from Tuesday through the upcoming
week, especially over the mountains of Southwest Montana and along
the Continental Divide. Temperatures will see-saw between 5 degrees
above to below normal through the upcoming work week within this
pattern, with periods of gusty south winds developing in the north-
south orientated valleys of Southwest Montana as the upper level
flow becomes more southerly in nature. - Moldan

- Forecast Confidence & Scenarios:

Gusty Winds through the day today...

Confidence remains high that gusty west winds will develop across
all of Southwest through North Central Montana today, most notably
from the late morning through evening hours. There is high
confidence that frequent wind gusts of between 30-40 mph will occur
across the region through this timeframe, with the strongest winds
occurring along the Rocky Mountain Front west of the I-15 corridor
and along the Montana Hwy 200/US Hwy 87 corridors between Great
Falls and Lewistown. One notable change from the past 48 hours has
been a northward shift in the strongest H850-700 winds, which are
now prog`d to reside between the Montana Hwy 200 and US Hwy 2
corridors. This northward shift from the past 48 hours, which had
been showing the core of strongest winds residing over the Montana
Hwy 200 corridor, has resulted in an increase (albeit still low) in
probabilities for wind gusts to exceed 55 mph along the US Hwy 2
corridor. It is not out of the realm of possibility that a few wind
prone locations across Glacier County and in lee of the Sweet Grass
Hills will reach or exceed High Wind criteria today; however, given
that these occurrences will be far and few between we will continue
to hold off on issuing any High Wind Warnings. None-the-less, those
traveling in high profile vehicles should be prepared for strong
cross winds.

Listed below are the NBM5.0 probabilities for wind gusts to exceed
35, 45, and 55 mph for select locations across North Central,
Central, and Southwest Montana.

                     Sunday`s Wind Gusts Probabilities
LOCATION               > 35 mph | > 45 mph | > 55 mph
Browning                 100%   |    85%   |    20%
Cut Bank                 100%   |    85%   |    25%
Havre                     95%   |    50%   |    10%
Great Falls               95%   |    50%   |    <5%
Lewistown                 65%   |     5%   |     0%
Helena                    80%   |    15%   |    <5%
Bozeman                   40%   |     5%   |    <5%
Dillon                    60%   |     5%   |     0%
Ennis                     50%   |     5%   |     0%
West Yellowstone          75%   |    <5%   |     0%


Accumulating Snow in the Mountains of Glacier National Park...

Confidence in minor snowfall accumulations has increased for the
mountains of Glacier National Park, mainly for those elevations
above 6500ft. Model guidance has settled in on better timing of
precipitation moving across the park as snow level fall, with this
overlap between both precipitation and "low" snow levels promoting
some minor accumulations of up to 1-2" for the higher peaks. Those
looking to recreate in the backcountry of Glacier National Park above
6500ft should be prepared for wet and raw conditions, along with the
potential for slippery trail conditions. - Moldan

&&

.AVIATION...
30/12Z TAF Period

Showers and isolated thunderstorms will gradually push east of all
terminals through 21-24z this afternoon, with increasing west
winds from between 15-21z persisting through 00-06z Monday.
Predominately low-VFR conditions through 21z will improve to VFR
conditions thereafter. Mountain obscuration along the Continental
Divide, especially over the Glacier National Park region, will
improve through 00-03z Monday.

For KGTF: Southwest winds will begin to turn to the west through
the late morning hours, with 15kt crosswinds being achieved
by as early as 16-18z this morning and then persisting through
02-04z Monday. Peak crosswinds are expected to occur between
21z-24z as west winds gust near 35kts. - Moldan


&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  67  47  78  49 /  30   0   0   0
CTB  61  45  74  47 /  20  10   0   0
HLN  69  44  78  49 /  30   0   0   0
BZN  70  40  77  45 /  70   0   0   0
WYS  62  30  70  35 /  70   0   0  20
DLN  70  39  79  44 /  30   0   0   0
HVR  69  49  77  50 /  50  10   0   0
LWT  66  44  75  48 /  70   0   0   0

&&

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

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