601
FXUS65 KTFX 012312
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
512 PM MDT Mon Sep 1 2025

Aviation Section Updated.

.KEY MESSAGES...

 - Temperatures will be hot this afternoon and Tuesday before
   cooling Wednesday through Friday.

 - Each day this week there is at least a low chance for isolated
   showers with chances peaking in Southwestern Montana on
   Saturday and Sunday.

 - There will be smoke/haze around North-central, Central, and Southwestern
   Montana for at least the next couple of days due to wildfires
   in the region.

&&

.DISCUSSION...
/Issued 132 PM MDT Mon Sep 1 2025/

 - Meteorological Overview:

This afternoon there is an upper-level ridge over North-central,
Central, and Southwestern Montana. This will allow temperatures to
warm up this afternoon with mostly dry weather. On Tuesday the upper-
level ridge remains over North-central, Central, and Southwestern
Montana with strong northwest flow aloft. Tuesday afternoon/evening
a cold front will move south from Canada. This will cool
temperatures down a few degrees along the Hi-line with above
seasonal average temperatures for the rest of North-central,
Central, and Southwestern Montana. Also due to the northwest flow
aloft there is the potential for very isolated showers Tuesday
afternoon and evening primarily in Hill and Blaine Counties. Due to
the hot temperatures on Tuesday combined with the northwest flow
there is also the potential for isolated thunderstorms primarily
in Hill and Blaine Counties.

Wednesday through Friday the upper-level ridge remains over North-
central, Central, and Southwestern Montana with strong northwest
flow aloft. This combined with the cold front will cool temperatures
down but they will remain above seasonal averages each day Wednesday
through Friday. Due to the northwest flow aloft there will be
isolated showers each day Wednesday through Friday. On Saturday the
upper-level ridge remains over North-central, Central, and
Southwestern Montana with weak upper-level flow. However, there is
an upper-level trough approaching the area. This will keep warm
temperatures around with showers and thunderstorms in Southwestern
Montana. On Sunday the upper-level trough remains over North-
central, Central, and Southwestern Montana which brings showers and
thunderstorms primarily to Southwestern Montana.

 - Forecast Confidence & Scenarios:

On Tuesday there is a 20 - 50% chance for a high of 90 degrees or
greater for the lower elevations near and along I-15 from Great
Falls through the Helena Valley and in the Gallatin Valley. On
Tuesday there is less than a 20% chance for thunderstorms across
North-central, Central, and Southwestern Montana. However due to
there being northwest flow aloft those probabilities are too low.
The greatest risk for thunderstorms on Tuesday is in Hill and Blaine
County. -IG

&&

.AVIATION...
02/00Z TAF Period.

Isolated shower and thunderstorm activity along the Rocky
Mountain Front and over the central island ranges will slowly
diminish through 02/04Z. Otherwise, light winds and VFR conditions
are expected tonight under hazy skies aloft. A cold front will
move southward through Central and North-central Montana on
Tuesday and bring a northerly wind shift and scattered mid- to
higher level cloudiness. A few afternoon widely scattered showers
or storms can also be expected, mostly for locations north and
east of a KCTB to KLWT line. - RCG

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

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  56  88  54  85 /  10   0   0   0
CTB  53  83  50  84 /  10   0   0   0
HLN  58  89  56  88 /   0   0   0   0
BZN  51  88  51  86 /   0   0   0   0
WYS  39  81  39  79 /   0  10   0   0
DLN  49  85  49  85 /   0   0   0   0
HVR  55  83  50  78 /   0  10   0   0
LWT  56  85  51  78 /   0   0   0   0

&&

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

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