448
FXUS65 KTFX 150651
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
1251 AM MDT Tue Sep 15 2026

.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...

 - 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...
15/06Z TAF Period

Fairly quiet conditions expected overnight and through this
afternoon, other than some passing clouds. An upper level
disturbance will move from west to east along the US/Canadian
border after 00z Wed, which will bring in some lower clouds and a
chance for showers near the US/Canadian border, mostly after 00z
Wed. Brusda

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  64  44  60  42 /   0  10  10   0
CTB  56  43  57  40 /  10  80  10   0
HLN  69  45  65  44 /   0   0  10   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  70  20   0
LWT  65  41  61  41 /   0   0   0   0

&&

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

&&

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