929
FXUS65 KTFX 240603
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
1203 AM MDT Mon Aug 24 2026

Aviation Section Updated.

.KEY MESSAGES...

 - Scattered thunderstorms this afternoon capable of strong wind gusts
   up to 80 mph and marginally large hail, mainly east of I-15
   ahead of a cold front.

 - Gusty winds behind a cold front this afternoon, with elevated
   fire weather conditions.

 - Generally near or above average temperatures this week with a few
   days of scattered showers and thunderstorms.

&&

.DISCUSSION...
/Issued 602 PM MDT Sun Aug 23 2026/

 - Meteorological Overview:

Potent upper level troughing moving across the region today will
bring an array of impacts, including strong to severe thunderstorms
and elevated fire weather conditions. A cold front will be moving
through today, which will delineate the transition between a more
thunderstorm focused risk and fire weather risk.

Ahead of the cold front ample moisture looks to coincide with
daytime heating and forcing from the passing upper level disturbance
to result in scattered showers and thunderstorms, mainly east of I-
15. Deep mixing and shear on the order of 30-40kts will support the
risk for large hail with initial storms before the risk transitions
to be more wind focused. Latest mesoanalysis features DCAPE in
excess of 1200 J/Kg over the plains, which would support the risk
for wind gusts approaching 80 mph in the strongest thunderstorms
that form. While PWATs are still elevated, the deep inverted-V
profiles will support a mix of wet and dry thunderstorms.

Behind the cold front a period of breezy west winds is forecast to
develop in most areas. The lowest portion of the atmosphere dries
out quite quickly behind the front, which will allow for relative
humidity to continue falling behind the front, even as temperatures
cool. The combination of the breezy and dry conditions, as well as
the potential for a few dry thunderstorms brings about an elevated
fire weather risk across most of the region.

Heading into Monday the upper system responsible for active weather
today will exit eastward. Weak ridging builds in across the west in
wake of this system, though with some lingering monsoonal moisture
near the Idaho border between Monida and West Yellowstone, a few
thunderstorms cannot be ruled out by late afternoon. The rest of the
region looks dry Monday.

The upper level ridging more or less persists much of the upcoming
week, but as it shifts slowly eastward an upper level trough
approaching the Pacific NW will slowly allow for showers and
thunderstorms to spread further and further northward across the
region each day. -AM

 - Forecast Confidence & Scenarios:

The main source of uncertainty today is with respect to how ongoing
convection over the plains north of Great Falls will modify the
convective environment this afternoon. On one hand this activity may
limit destabilization in some areas where forcing is greatest.
Conversely this activity and associated outflow may serve as a focus
for additional convective initiation mid-afternoon, resulting in
perhaps a greater areal extent of convective activity.
ADditionally, if this activity persists, it could eventually break
the cap and intensify and become the main area of concern across
the Hi-Line. Nonetheless, any thunderstorm that forms this
afternoon will be capable of strong wind gusts, and at least
briefly large hail. -AM

&&

.AVIATION...
24/06Z TAF Period

Wildfire smoke from the Camp Creek Fire will impact portions of
North Central and Central Montana through the overnight hours. For
most locations this will only impact slantwise visibility but
surface-level visibility impacts are possible at KGTF and KLWT.
Once northerly winds start to pick up after sunrise the plume of
smoke is expected to be pushed further south which will help clear
out KGTF/KLWT but may bring some slantwise visibility reductions
towards KHLN. Breezy winds are expected again on Monday afternoon
across the northern plains.

Overnight there is a slight chance for fog developing around KWYS
but confidence was not high enough to include it in the TAF.
Isolated thunderstorms are possible across portions of Southwest
Montana late Monday into early Tuesday but confidence in any
impacts to the terminals is low.

Mountain obscuration will remain a concern where wildfire smoke is
present and around any potential thunderstorm activity.


For KGTF: Calm winds will continue through the night with periods
of MVFR conditions expected through 24/17Z when the latest smoke
models start pushing smoke away from KGTF as more northwesterly
winds start to set up. Crosswinds are expected through the afternoon
but the risk of seeing crosswinds over 15kts is currently at 20%.
While slantwise visibility is expected to improve somewhat after
24/17Z, there is a possibility that smoke aloft may start to
return later in the day depending on how the Camp Creek Fire
behaves. Greater impacts to slantwise visibility may start to
return after 24/22Z and last through the remainder of the evening.
-thor

&&

.FIRE WEATHER...

A surface front will bring gusty westerly winds through the
afternoon hours across the region. Widespread gusts over 35 mph
are possible and will be enhanced by any thunderstorm activity
that develops. Minimum RH values will be most critical in
Southwest Montana where the RFW is currently in effect for Sunday
afternoon and evening. Further north, conditions will be windy but
not quite as dry. Additionally there is some disagreement in the
latest models as to how the thunderstorms will develop and how
widespread they will be. With this uncertainty in place the
decision was made to hold off on issuing a RFW for North-Central
Montana for now. But elevated to near-critical fire weather
conditions will be a concern across the entire region. Where
thunderstorms do develop, the concerns will be frequent lightning
and gusty/erratic winds which may lead to new fire starts and make
new and/or existing fires difficult to contain.  -thor

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  54  80  52  83 /   0   0   0   0
CTB  50  76  48  78 /   0   0   0   0
HLN  50  83  53  85 /   0   0  10  10
BZN  48  82  49  84 /  10   0  10  20
WYS  39  79  40  78 /  20   0  20  30
DLN  47  84  49  84 /   0   0  20  20
HVR  55  82  51  83 /  10   0   0   0
LWT  52  78  48  81 /  30   0   0   0

&&

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

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