Big Sky Resort

000
FXUS65 KTFX 151809
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
1209 PM MDT Tue Sep 15 2026

Aviation Section Updated.

.KEY MESSAGES...

 - Areas of rain near the Canadian border late today into tonight. 

 - Dry Wednesday ahead of showers and thunderstorms Thursday and 
   Friday. 

 - Warmer and drier by the end of the weekend. 

&&

.DISCUSSION...
/Issued 353 AM MDT Tue Sep 15 2026/ 

 - Meteorological Overview:
A fast moving trough within a northwesterly flow aloft along the 
BC/Pac NW coast will slow considerably through the day today as it 
intensifies and eventually splits some of its energy. The weaker 
portion of this troughing skirts across the Canadian border this 
evening and tonight, which will foster some generally light rain 
near and north of Highway 2. 

The stronger portion of the aforementioned trough becomes cutoff 
over northern CA/vicinity Wednesday, leading to a southwesterly flow 
aloft developing across the Northern Rockies. Temperatures look to 
trend warmer as a result of this flow aloft, but given the 
anticyclonic nature of the flow typical afternoon and evening shower 
and thunderstorm activity looks to hold off til Thursday as the core 
of the upper disturbance begins its approach. 

Showers and thunderstorms, a few on the strong side, look to develop 
Thursday afternoon, initially across Southwest Montana. Uncertainty 
increases Thursday night into Friday with respect to the track and 
timing of the upper disturbance, though there will be at least some 
risk for another round of showers and thunderstorms by Friday 
afternoon. 

Looking toward the weekend the upper level disturbance begins to 
exit eastward. A few lingering showers early Saturday morning cannot 
be ruled out ahead of a drying trend through the remainder of the 
weekend into early next week. -AM

 - Forecast Confidence & Scenarios:
The largest source of uncertainty is with respect to the timing
and track of the upper level disturbance Thursday into Friday. A
slower track, or one that keeps the Northern Rockies within a
southwesterly flow aloft longer would foster a second day of
showers and thunderstorms. The track of this disturbance will also
play a large role in how much shear and resulting risk for
organized severe weather will materialize. -AM

&&

.AVIATION...
15/18Z TAF Period 

Generally mild conditions expected through this afternoon. After 00Z 
Wednesday, an upper level disturbance will move along the 
US/Canadian border from west to east and bring the potential for 
showers in north central MT. Showers are expected to move out of the 
region by 09Z Wednesday night. Additionally, lower clouds bases may 
cause mountain obscuration at times in north central and central MT 
after 00Z Wednesday. - ESH

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  64  44  60  42 /   0  10   0   0 
CTB  56  43  57  40 /  10  60  20   0 
HLN  69  45  65  44 /   0   0   0   0 
BZN  71  37  69  39 /   0   0   0   0 
WYS  65  26  72  36 /   0   0   0  30 
DLN  71  36  71  41 /   0   0   0  10 
HVR  65  43  64  41 /   0  40  10   0 
LWT  65  41  61  41 /   0   0   0   0 

&&

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

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