337
FXUS65 KTFX 161126
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
526 AM MDT Sun Aug 16 2026

Aviation Section Updated.

.KEY MESSAGES...

 - It will gradually warm up through the end of the work week.

 - Showers and thunderstorms will linger through early next week
   with Monday and Tuesday having the most widespread showers and
   thunderstorms.

 - Thunderstorms will return next weekend with breezy conditions.


&&

.DISCUSSION...
/Issued 112 AM MDT Sun Aug 16 2026/

 - Meteorological Overview:

Today an upper-level ridge with southwest flow aloft is over North-
central, Central, and Southwestern Montana. This will allow
temperatures to warm up a few more degrees to be around seasonal
averages. An upper-level shortwave will move through the flow and
bring isolated showers and thunderstorms to North-central, Central,
and Southwestern Montana this afternoon/evening. On Monday the upper-
level ridge with southwest flow aloft remains over North-central,
Central, and Southwestern Montana. 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:

This morning in any areas that clear fog has a high chance to
form. The areas that have the greatest risk for fog forming this
morning are the valleys of Southwestern Montana and along the
river valleys of North-central Montana. On Sunday there is a 20 -
35% chance for thunderstorms across North-central, Central, and
Southwestern Montana.

Monday afternoon/evening into Tuesday the track and timing of the
upper-level ridge breakdown/upper-level trough moving through the
area will affect the strength of thunderstorms Monday afternoon
through Tuesday. On Monday there is a 15 - 25% chance for
thunderstorms across North-central and Central Montana. On Monday
there is a 25 - 35% chance for thunderstorms in Southwestern
Montana. On Tuesday there is a 30 - 40% chance for thunderstorms
across Central and Southwestern Montana. On Tuesday there is a 15
- 25% chance for thunderstorms across North-central Montana. -IG

&&

.AVIATION...
16/12Z TAF Period

VFR conditions will prevail across all terminals during this TAF
Period outside of during any thunderstorms. Between 16/18Z and
17/06Z isolated showers and thunderstorms will affect all of the
terminals. All thunderstorms will produce frequent lightning, a
brief heavy downpour, and gusty, erratic winds. During any
thunderstorms there will be a brief period of mountain
obscuration. -IG

For KGTF: There will be light winds during this TAF Period with a
very low chance for exceeding a 15 kt crosswind. However there is
around a 20% chance for thunderstorms to affect KGTF between
16/21Z and 17/03Z. The primary risks from any thunderstorms will
be gusty, erratic winds up to 35 kts and lightning. -IG

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  83  52  81  52 /  40  40  10  20
CTB  75  47  74  47 /  20  20  10  20
HLN  82  51  81  55 /  30  40  10  10
BZN  80  48  80  50 /  40  50  10  40
WYS  75  36  76  39 /  30  30  20  40
DLN  77  46  79  49 /  40  40  10  40
HVR  84  51  81  50 /  30  30  30  20
LWT  79  50  77  49 /  30  30  20  30

&&

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

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