041
FXUS65 KTFX 162338
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
538 PM MDT Sun Aug 16 2026

Aviation Section Updated.

.KEY MESSAGES...

 - Shower and thunderstorms chances continue through Tuesday, with
   some of the stronger storms producing gusty outflow winds and
   heavy downpours.

 - Temperatures near normal through much of the upcoming week.

 - Gusty winds return from the middle of the work week through the
   upcoming weekend, which combined with dry conditions will lead
   to elevated fire weather conditions.

&&

.DISCUSSION...
/Issued 1151 AM MDT Sun Aug 16 2026/

 - Meteorological Overview:

Monsoonal moistures lifting north and east around upper level
ridging centered over the Central Rockies through the Desert
Southwest will support another day of scattered to numerous showers
and thunderstorms across Southwest Montana, with isolated to widely
scattered showers and storms over Central and North Central Montana.
While showers and thunderstorms will decrease in coverage through
the late evening hours tonight an isolated shower or storm can`t be
ruled out into the early morning hours on Monday, most notably over
the plains of Central and North Central Montana where weak low level
frontogenetic forcing will reside throughout the overnight hours.
Partly clearing skies beyond midnight tonight combined with recent
precipitation and light winds will support another opportunity for
patchy fog across the Northern Rockies; most notably in the prone
valleys of Central and Southwest Montana. - Moldan

By Monday evening the upper-level ridge begins to break down and an
upper-level trough begins to move over the area. This will bring
breezy conditions to the area with showers and thunderstorms Monday
afternoon and evening. Temperatures will remain near seasonal
averages on Monday.

On Tuesday there will be zonal flow (west - east) over North-
central, Central, and Southwestern. This will allow temperatures to
remain near seasonal averages with breezy conditions. There will
also be showers and thunderstorms across North-central, Central, and
Southwestern Montana on Tuesday. On Wednesday and Thursday an upper-
level ridge begins to build back in across North-central, Central,
and Southwestern Montana. On Wednesday and Thursday temperatures
will remain around seasonal averages. On Wednesday and Thursday it
will be mostly dry across the area. On Friday the upper-level ridge
is over North-central, Central, and Southwestern Montana. This will
bring hot and dry weather to the area. On Saturday an upper-level
trough begins to move over North-central, Central, and Southwestern
Montana. This will bring showers and thunderstorms back to the area.
Due to strong low-level and mid- level winds it will be breezy on
Saturday. -IG

 - Forecast Confidence & Scenarios:

Showers and Thunderstorms through Tuesday...

Sufficient shear, but marginal instability, will help to support
continued chances for convection through the first half of the
upcoming work week as monsoonal moisture continues to lift north and
east around broad ridging centered over the Central Rockies and
Desert Southwest. Inverted-V soundings and and tall skinny CAPE
profiles support the potential for gusty outflow winds and the
potential for periods of heavy rainfall, especially across Southwest
Montana.

Gusty Winds from Wednesday through next Sunday...

Increasing zonal to southwesterly flow aloft will support gusty
winds, most notably during the afternoon and evening hours, from the
middle to the work week through next weekend with the exception of
Thursday. These gusty southwest to west surface winds will initially
occur along the Rocky Mountain Front on Wednesday, with a 20-30%
chance that gusts exceed 35 mph. By Friday NBM5.0 probabilities for
wind gusts exceeding 35 mph expand to all areas, with probabilities
increasing to between a 20-60% chance for the upcoming weekend.
While 35 mph wind gusts are not unusual, let alone noteworthy during
the windy season, moderating temperatures and dry conditions will
lead to increasing fire weather concerns given these speeds. - Moldan

&&

.AVIATION...
17/00Z TAF Period

Scattered showers and thunderstorms across the whole region are
moving eastward producing brief strong, gusty winds, cloud to
ground lightning, and localized moderate to heavy rain. Most
convection will end by 04Z tonight then overnight there is a 40%
chance for patchy fog and mist to set up again between 17/09 and
17/16Z in the KWYS area with MVFR to IFR ceilings and visibility
most likely. VFR conditions are expected throughout the rest of
the terminals tonight into the morning. Tomorrow afternoon will
see more isolated coverage for thunderstorms mainly for the
Northern and Southwestern terminals.

For KGTF: Prevailing winds tonight will be light and variable
with VFR conditions. Winds will shift to the Northwest after
17/21Z at around 9 KT predominantly. Currently there is only a 10%
chance for isolated showers and thunderstorms tomorrow afternoon.
- Akins

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  52  83  54  84 /  20  20  10  20
CTB  48  77  48  79 /  20  20  20  10
HLN  51  84  55  83 /  20  20  20  20
BZN  48  81  50  81 /  50  10  30  20
WYS  35  77  39  76 /  30  30  40  40
DLN  47  80  50  79 /  30  20  30  30
HVR  52  83  51  85 /  20  20  20  10
LWT  50  79  52  79 /  20  20  10  40

&&

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

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