Big Sky Resort

000
FXUS65 KTFX 281119
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
519 AM MDT Tue Jul 28 2026

Aviation Section Updated.

.KEY MESSAGES...

 - Remaining hot through the rest of the work week, with the
   hottest day of the upcoming week occurring on Saturday.

 - Winds increase late Saturday and last into Sunday, with the
   strongest winds occurring along the Rocky Mountain Front.

 - Brief reprieve from the heat early next week.

&&

.DISCUSSION...
/Issued 1205 AM MDT Tue Jul 28 2026/ 

 - Meteorological Overview:

Upper level ridging will dominate through much of the forecast 
period, with the ridge bringing continued hot temperatures to most 
locations from Southwest through North Central Montana until 
Saturday. By Sunday a potent longwave trough will breakdown the 
ridge and bring increasing winds and slightly cooler temperatures to 
the Northern Rockies, with temperatures falling below normal into 
the day on Monday in wake of a cold front. Monsoonal moisture 
lifting up and around the ridge will provide daily chances for 
isolated showers and storms; however, most locations will remain dry 
over the next week. - Moldan

 - Forecast Confidence & Scenarios:

Return of Extreme Temperatures by Saturday...

While temperatures will remain hot through the remainder of the work 
week climate anomaly indicators have honed in on Saturday being the 
hottest day of the upcoming week, with values becoming unusual to 
very unusual with respect to late July/early August climatology. The 
fact that these climate anomaly indicators are suggesting another 
period of hot temperatures is remarkable considering that August 1st 
is (at most locations) only one day past 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     |     98
Cut Bank                  95   |     100     |    104
Havre                    103   |     108     |    111
Great Falls              102   |     105     |    107
Lewistown                 98   |     101     |    104
Helena                    97   |     100     |    104
White Sulphur Springs     95   |     102     |    101       
Bozeman                   98   |      98     |    105
Dillon                    95   |      98     |    100
Ennis                     94   |      98     |    100
West Yellowstone          89   |      93     |     96

Given the presence of regional wildfires across the Northern Rockies 
the "High End" scenario will be tough to reach due to decreased 
solar insolation from the smoke, with dense smoke having the ability 
to hold temperatures back some 5 to 10 degrees.

Strong Winds from Saturday night through Sunday...

Confidence is increasing that a period of strong, nearing high, 
winds will impact the Rocky Mountain Front from Saturday night 
through the day on Sunday due to the combination of mountain wave 
activity (from the late evening hours on Saturday through Sunday 
morning) and deep mixing (during the daylight hourS on Sunday). H700 
winds per NAEFS analysis are prog'd to reach 40-50kts from Saturday 
evening through Sunday morning across the aforementioned area, which 
is 2 to nearly 3 standard deviations above normal. The table below 
are the NBM5.0 probabilities for wind gusts to exceed 45 mph, 55 
mph, and 65 mph for select locations along the Rocky Mountain Front 
for the previously mentioned timeframe.

                    Probabilities for Wind Gusts to Exceed
LOCATION               >45 mph |   >55 mph   |  >65 mph
Many Glacier Valley      55%   |     15%     |    <5%
Logan Pass               50%   |     10%     |     0%
St Mary                  80%   |     40%     |    10%
Two Medicine Valley      70%   |     30%     |    10%
East Glacier             75%   |     25%     |    10%
Browning                 70%   |     25%     |     5%
Cut Bank                 75%   |     20%     |     5%
Heart Butte              80%   |     30%     |    20%
Choteau                   5%   |      0%     |     0%       
Augusta                  20%   |     <5%     |     0%

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. - Moldan

&&

.AVIATION...
28/12Z TAF Period 

Regional wildfire smoke will continue to bring MVFR/low-VFR 
conditions to terminals at times through the TAF period, with 
additional impacts to slantwise visibility upon ascent/descent. 
Isolated to widely scattered showers and thunderstorms developing 
across across Northeast Idaho and Southwest Montana this afternoon 
will lift northeast and across the remainder of Southwest and into 
portions of Central Montana through the evening hours tonight; with 
the KEKS and KBZN terminals having the "highest", albeit a 30% 
chance, of seeing activity.

For KGTF: Light southwest winds through 15-16z this morning will 
becoming increasingly variable throughout the remainder of the 
morning and early afternoon hours. By 21z this afternoon winds will 
begin to turn more to the west, with the probabilities for this west 
wind exceeding a 15kt crosswind being 10% from 28/23z to 29/02z. - 
Moldan

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  95  61  94  60 /   0   0   0   0 
CTB  91  56  89  55 /   0   0   0   0 
HLN  94  59  93  59 /  10   0  10  10 
BZN  94  58  92  57 /  20   0  20  10 
WYS  88  49  85  47 /  10   0  30  20 
DLN  91  55  88  54 /  10   0  20  10 
HVR  98  60  95  59 /   0   0   0   0 
LWT  93  58  90  57 /  20  20  10  20 

&&

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

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