208
FXUS65 KTFX 180736
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
136 AM MDT Tue Aug 18 2026

.KEY MESSAGES...

 - Showers and thunderstorms will affect the area this
   afternoon/evening.

 - Temperatures will be around seasonal averages throughout this
   week.

 - It will be dry Wednesday through Friday with thunderstorms
   returning this weekend with breezy conditions.

&&

.DISCUSSION...

 - Meteorological Overview:

Today there will be zonal flow (west - east) over North-central,
Central, and Southwestern Montana. This will allow temperatures
to remain near seasonal averages with breezy conditions due to
modestly strong low and mid-level winds. There will also be
showers and thunderstorms across North-central, Central, and
Southwestern Montana this afternoon/evening. On Wednesday an
upper-level ridge begins to build back in across North-central,
Central, and Southwestern Montana. On Wednesday temperatures will
be around seasonal averages with dry weather. On Thursday the
upper-level ridge remains over North-central, Central, and
Southwestern Montana. This will keep warm and dry conditions for
the area on Thursday. On Wednesday and Thursday upper-level
shortwaves will move through the upper-level flow and bring breezy
conditions to North-central, Central, and Southwestern Montana.

On Friday the upper-level ridge remains over North-central,
Central, and Southwestern Montana. This will bring hot and dry
weather to the area. An upper-level shortwave will move through
the upper-level flow and bring breezy conditions to North-
central, Central, and Southwestern Montana. 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 modestly strong low-level and mid-level
winds it will be breezy on Saturday. On Sunday the upper-level
trough is over North-central, Central, and Southwestern Montana.
This will cool down temperatures slightly and bring another round
of showers and thunderstorms to the area. On Sunday due to
modestly strong low and mid-level winds it will be breezy across
North-central, Central, and Southwestern Montana. On Monday an
upper-level ridge moves over North-central, Central, and
Southwestern Montana. This will bring warm and mostly dry weather
to the area on Monday. -IG

 - Forecast Confidence & Scenarios:

Today the Storm Prediction Center (SPC) issued a Marginal Risk (5%
chance for wind gusts of 58 mph or greater within 25 miles of a
point) for Choteau, Judith Basin, Fergus, and Southern Blaine
Counties. Today there is a 20 - 35% chance for thunderstorms
across North-central, Central, and Southwestern Montana.

Winds will increase and relative humidity will decrease Wednesday
through Sunday which will lead to elevated fire weather conditions.
Saturday evening through Sunday is the time period when the winds
increase the most and so Sunday afternoon currently has the greatest
risk for near critical fire weather conditions. This risk is
contingent on the track of the upper-level trough that moves through
Saturday evening into Sunday. -IG


&&

.AVIATION...
18/06Z TAF Period

VFR conditions prevail through the period for most terminals with
a few showers moving through Southwest MT from 08Z to 12Z this
morning. Some mountain obscuration and reduced visibility in the
rain is possible. There is a 10% chance for MVFR visibility and
ceilings in the vicinity of KWYS from 18/09Z to 13Z. Scattered
thunderstorms and showers are expected to develop throughout the
region from 18/21Z to 19/01Z impacting most terminals. The primary
hazards with these storms will be brief, gusty winds, cloud-to-
ground lightning, localized heavy rain, and small hail. Light
smoke could slightly reduce visibility for KCTB and KVHR tomorrow
afternoon as well.


For KGTF: Winds will be light and variable tonight shifting to a
prevailing westerly at 10G15 KT after 18/19Z. There is a 20%
chance for thunderstorm activity in the terminal area from 18/21Z
to 19/00Z which could briefly create outflows that exceed
crosswind thresholds. - Akins

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  83  53  86  54 /  20  10   0   0
CTB  77  51  82  51 /  20  10   0   0
HLN  83  51  85  54 /  20  10   0   0
BZN  80  49  84  51 /  30  30   0   0
WYS  75  36  79  39 /  30  30   0   0
DLN  80  47  83  49 /  20  20   0   0
HVR  84  54  86  54 /  20  20   0   0
LWT  79  51  82  52 /  30  20   0   0

&&

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

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