786
FXUS65 KTFX 302300
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
500 PM MDT Thu Jul 30 2026

Aviation Section Updated.

.KEY MESSAGES...

 - Scattered thunderstorms are possible across Southwest and
   Central Montana through the evening hours with lightning and
   gusty winds the main concerns.

 - Wildfire smoke will bring hazy skies or smoky conditions to the
   Northern Rockies, with air quality degradation through the
   week.

 - Hot temperatures will continue through Saturday, with Saturday
   being the hottest day.

 - High Winds are possible along the Rocky Mountain Front Saturday
   night through Sunday morning, with gusty winds expanding to all
   areas on Sunday.

&&

.DISCUSSION...
/Issued 257 PM MDT Thu Jul 30 2026/

 - Meteorological Overview:

Upper level ridging through the day on Saturday will help to
maintain well above normal temperatures across all of the Northern
Rockies, with high temperatures peaking on Saturday as increasing
flow and strong warm air advection brings readings into the mid-90s
to near 110 degrees. While overall dry conditions will persist
beneath this ridge there remains enough monsoonal moisture spreading
north and east across portions of Southwest and into Central Montana
to support isolated to widely scattered showers and thunderstorms
during the afternoon and evening hours through Friday. Biggest
impact from the showers and thunderstorms will be gusty and erratic
outflow winds. By Saturday night the upper level ridge will be
broken down by a potent upper level trough sliding east across
Southern Canada, with this trough and attendant (dry) cold front
brining gusty winds to all areas for the day on Sunday and below
temperatures for the day on Monday. - Moldan


 - Forecast Confidence & Scenarios:

Thunderstorms Today...

Isolated showers have already started popping up across portions
of Central and Southwest Montana. In general most of these
thunderstorms are expected to be on the drier side which means
cloud to ground lightning and gusty, erratic winds will be a
concern for potential new fire starts through this evening. While
the threat for severe weather remains a bit marginal there is
still a concern for some strong gusts, especially east of a line
between Havre and Lewistown where isolated gusts up to 70 mph are
possible with any stronger thunderstorm that is able to develop.
After today the chance for precipitation is near zero through at
least early next week.  -thor


Return of Extreme Temperatures by Saturday...

Climate anomaly indicators remain honed in on Saturday being the
hottest day of the upcoming week, with ECMWF EFI values peaking
between 0.75 and 0.9 across Southwest through North Central Montana;
which continues to suggest unusual to very unusual hot temperatures
with respect to early August climatology. This is remarkable
considering that August 1st is only one day removed from the
climatological peak for average high temperatures across Southwest
through North Central Montana.

The table below represents the potential high temperature scenarios
for select cities across Southwest through North Central Montana,
with the "Low End" scenario being the NBM10Pct (10% chance that
temperatures are lower than the listed value), "Most Likely"
scenario being the NBM50Pct, and the "High End" scenario being the
NBM90Pct (10% chance that temperatures exceed the listed value).

                    Saturday`s High Temperature Scenarios
LOCATION               Low End | Most Likely | High End
Browning                  88   |      93     |     95
Cut Bank                  95   |     100     |    102
Havre                    104   |     108     |    110
Great Falls              102   |     103     |    105
Lewistown                 98   |     101     |    103
Helena                    98   |     100     |    104
White Sulphur Springs     94   |      97     |     99
Bozeman                   99   |     103     |    105
Dillon                    94   |      97     |     98
Ennis                     93   |      97     |     99
West Yellowstone          89   |      91     |     93

While wildfire smoke can significantly influence high temperatures
by limit heating...the past few days have only seen minor impacts to
forecasted highs. Therefore the earlier (in the week) concerns that
I had on forecasted highs being held below the 50Pct, or "Most
Likely" scenario, on Saturday have decreased. Given this increased
confidence in hot temperatures occurring on Saturday, most notably
over portions of the Central and North Central Montana plains, an
Extreme Heat Watch has been issued from 18z Saturday through 18z
Sunday due to the hot daytime temperatures and limited cooling (as
compared to climatology) during the overnight hours.

High Winds from Saturday night through Sunday morning...

H700 winds of 40-60kts, which is an impressive 3 to nearly 4
standard deviations above normal per NAEFS analysis, are prog`d to
overspread the Rocky Mountain Front from 00z Sunday through 18z
Sunday. BUFKIT soundings support ideal thermal profiles, especially
between 06z and 14z Sunday, for mountain wave activity across the
Eastern Glacier Park Region out to Cut Bank. This anomalous cross
barrier flow combined with the potential for mountain wave activity
has increased concerns that High Winds could materialize across all
of Glacier County and portions of western Toole and central Pondera
Counties. For this reason a High Wind Watch has been issued from 03z
Sunday through 18z Sunday for these areas, with the most concerning
timeframe being between 06-14z Sunday. Those looking to travel or
recreate along the Rocky Mountain Front should be prepared for
strong winds; which could make driving and hiking difficult, lead to
falling trees in the backcountry, and/or lead to the spread of
existing/new wildfires.

The table below represents the potential wind gust scenarios for
select locations along the Rocky Mountain Front, with the "Low End"
scenario being the NBM10Pct (10% chance that gusts are lower than
the listed value), "Most Likely" scenario being the NBM50Pct, and
the "High End" scenario being the NBM90Pct (10% chance that gusts
exceed the listed value).

                Saturday Night/Sunday Wind Gust Scenarios
LOCATION               Low End | Most Likely | High End
Many Glacier Valley    35 mph  |    50 mph   |  60 mph
Logan Pass             35 mph  |    45 mph   |  55 mph
St Mary                40 mph  |    55 mph   |  65 mph
Two Medicine Valley    40 mph  |    60 mph   |  70 mph
Marias Pass            35 mph  |    40 mph   |  50 mph
East Glacier           45 mph  |    55 mph   |  65 mph
Browning               40 mph  |    45 mph   |  60 mph
Cut Bank               40 mph  |    45 mph   |  55 mph
Heart Butte            40 mph  |    50 mph   |  65 mph

- Moldan


&&

.AVIATION...
30/18Z TAF Period

VFR conditions will prevail across all terminals during this TAF
Period. Between now and 31/04Z there is a 15% chance for
thunderstorms at the KBZN, KEKS, KWYS, and KHLN terminals. Any
thunderstorms will produce heavy rainfall, small hail, frequent
lightning, and gusty, erratic winds. Across most of the TAF sites
smoke from wildfires will reduce slantwise visibility.

For KGTF: Light and variable winds will persist through this
forecast period. As a result there is a very low chance of
exceeding a 15kt crosswind during this forecast period. -IG

&&

.FIRE WEATHER...

Elevated to critical fire weather conditions is expected Saturday
afternoon through Sunday evening across North-Central, Central,
and Southwest Montana. On Saturday, hot temperatures in the upper
90s to near 110 degrees will combine with minimum RH values as
low as 8% and gusts up to 50 mph with stronger gusts expected
along the Rocky Mountain Front to create the potential for
critical fire weather conditions. Sunday will be cooler but low RH
values and strong winds are still expected which will still pose
a significant concern not only for ongoing fires but any potential
new starts that occur. A Fire Weather Watch remains in effect from
Saturday afternoon through Sunday evening across all of North-
Central, Central, and Southwest Montana.  -thor

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  60  97  59 103 /  10   0   0   0
CTB  54  91  54  96 /   0   0   0   0
HLN  59  95  59 100 /  40   0   0   0
BZN  56  94  57 101 /  20   0   0   0
WYS  45  87  46  91 /  20   0   0   0
DLN  53  89  55  95 /  20   0   0   0
HVR  58  97  57 106 /  10   0   0   0
LWT  58  92  58 100 /  20   0   0   0

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
Extreme Heat Watch from Saturday afternoon through late Saturday
night for Cascade County below 5000ft-Eastern Pondera and
Eastern Teton-Judith Basin County and Judith Gap.

Fire Weather Watch from Saturday afternoon through Sunday
evening for Central and Eastern Lewis and Clark National Forest
Areas-Chouteau and Fergus Counties-Eastern
Glacier/Toole/Central/Eastern Pondera/Liberty-Helena and
Townsend Ranger Districts of the Helena National Forest-Hill and
Blaine Counties-Lewis and Clark National Forest Rocky Mountain
District-Rocky Mountain Front-Lincoln Ranger District of the
Helena National Forest.

High Wind Watch from Saturday evening through Sunday morning for
East Glacier Park Region-Eastern Glacier, Western Toole, and
Central Pondera-Northern High Plains.

Extreme Heat Watch from Saturday afternoon through Sunday
morning for Bears Paw Mountains and Southern Blaine-Fergus
County below 4500ft-Western and Central Chouteau County.

&&

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