Dillon, Montana 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

782
FXUS65 KTFX 122022
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
222 PM MDT Tue Aug 12 2025

.KEY MESSAGES...

 - Very warm, dry and windy conditions on Wednesday will bring an
   elevated fire weather risk.

 - Isolated thunderstorms with gusty winds and little
   precipitation are expected across primarily southwest Montana
   late today and again Wednesday.

 - Cooler temperatures are expected Thursday with seasonably warm
   conditions prevailing this weekend.

&&

.DISCUSSION...

 - Meteorological Overview:

A fairly zonal west to east flow is in place across the Northern
Rockies and MT through the rest of the work week as upper level
ridging gradually retrogrades westward toward the SW US and upper
troughing lingering off the west coast ejects several waves by to
our north across Canada.

A subtle shortwave/upper jet disturbance embedded within WNW flow
across the Northern Rockies tracks across SW MT late this afternoon
and evening, which may lead to a few thunderstorms across primarily
Madison and Gallatin counties. Cannot completely rule out some
isolated convection further north across central/north-central MT,
but a subsidence inversion around 600MB noted on the 18z KTFX
sounding is likely to provide enough convective inhibition to keep
the risk low and mainly limited to areas near the island ranges
and Little Belts. Main concern with any thunderstorm activity late
this afternoon and evening will be gusty downdraft/outflow winds
due to high cloud-bases and dry low levels.

On Wednesday, larger scale troughing shifting inland across BC/AB
will compress/increase the westerly flow aloft across the Northern
Rockies while also aiding int the development of surface/lee-side
troughing in southern AB. Afternoon mixing will transport these
stronger winds to the surface with widespread gusts exceeding 25-30
mph across the area and gusts in excess of 40 mph likely (>60%
probability) along the Rocky Mtn Front and most of Glacier County.
Temperatures will warm into the 90s across much of the area as well
with low afternoon humidity leading to elevated fire weather
conditions (See fire wx discussion for additional info). The risk
for thunderstorms on Wednesday will mainly be limited to portions of
SW MT along/south of I-90.

A cold front moving south from Canada will spread cooler
temperatures across north-central and central MT Thursday with warm
and breezy conditions persisting in southwest MT still Thursday
afternoon before these areas cool Thursday night. A southwest flow
aloft sets up this weekend into next week as upper level ridging
tries to build westward across the SW US while troughing remains in
place near/off the west coast of Canada. Temperatures will warm back
to near and slightly above seasonal averages this weekend before
warming further early next week. Some moisture is likely to become
entrained into the flow and bring low chances for daily thunderstorm
development as early as Sunday, but there is still considerable
uncertainty at this time with specifics of moisture and
disturbances to move through area Sunday through early next week.

 - Forecast Confidence & Scenarios:

Thunderstorm risk this afternoon/evening ranges from 10-30%
across Madison and Gallatin counties with highest probability
from Yellowstone NP into southern Gallatin county. There is a
10-15% risk of thunderstorms across portions of north-central MT
near the Canadian border and island mountain ranges. Hoenisch

&&

.AVIATION...
12/18Z TAF Period

This afternoon, isolated showers and thunderstorms are expected to
develop in Southwest MT along and south of the I-90 corridor.
Gusty winds will be possible with any shower or thunderstorm.
Other than that, you can expect a few mid level clouds over North-
Central MT through the TAF period. -Wilson

Refer to weather.gov/zlc for more detailed regional aviation
weather and hazard information.

&&

.FIRE WEATHER...

Fire weather concerns will be elevated on Wednesday with very warm
afternoon temperatures and low afternoon humidity combined with
breezy to windy conditions across much of the area. The most
critical conditions are expected across southwest MT where fuels are
drier. Further north across most of central/north-central MT,
fuels/fire danger are not at critical thresholds following recent
precipitation, but the very warm, dry and windy conditions will bring
an elevated risk for fire spread in areas where fuels may be
locally more receptive. Hoenisch

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  60  92  56  79 /  10   0   0   0
CTB  56  87  51  71 /   0   0  10   0
HLN  59  93  57  86 /   0   0   0   0
BZN  55  94  53  89 /  10  10   0   0
WYS  43  84  41  81 /  20  30  10  10
DLN  52  90  49  87 /  10  10   0   0
HVR  59  94  55  76 /  10   0   0   0
LWT  58  89  54  78 /  10   0   0   0

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
&&

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