120
FXUS65 KTFX 201726
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
1126 AM MDT Sun Sep 20 2026

Aviation Section Updated.

.KEY MESSAGES...

- Rain continues to slowly exit Central MT throughout the morning.

- Dry conditions and warm temperatures settle in for most of the
  week.

- Unsettled weather and a cool down in temperatures possible next
  weekend.

&&

.DISCUSSION...
/Issued 501 AM MDT Sun Sep 20 2026/

 - Meteorological Overview:

The vertically stacked low pressure system will continue to slide
eastwards throughout the day. With it will also pull the
precipitation over Central MT. However, expect light rain to
continue over Central MT through at least the morning hours.
Isolated showers may linger in eastern Fergus County through
Sunday afternoon. As this storm system exits, high pressure moves
into the region, creating low level stability. The calm
conditions with breaking in the clouds overnight tonight will
bring the potential for fog to develop mainly in Southwest MT this
morning. Similar conditions set up Monday morning, with the
potential for fog development to shift into North-Central MT as
well.

A drier weather pattern sets up for most of the week as the current
storm system moves east and another shortwave slides south of
Montana across the Great Basin. As this shortwave slides across the
Great Basin region, areas near the MT/ID border might get clipped
with a few rain showers late Tuesday night. For the second half of
the week, southwest flow dominates as the next incoming trough
builds off of the western U.S. coast. Above normal temperatures
are expected through Friday.

Ensembles hint at this upper-level trough moving through next
weekend, bringing back chances for precipitation. This trough
also pushes temperatures down closer to normal, and may lower
snow levels to the higher mountain peaks. -Wilson

 - Forecast Confidence & Scenarios:

There still remains some uncertainty in fog development across the
Southwest MT valleys this morning. The main uncertainty is forecast
soundings also showing low stratus also developing, which could
prohibit fog potential. The best chances for fog development will be
in the higher Southwest MT valleys. There`s a 10-20% chance for fog
development this morning. Monday morning, hi-res guidance shows
greater probabilities, with a 30-60% chance for fog with less than a
mile of visibility along US Highway 2 from Havre to Cut Bank.
-Wilson

&&

.AVIATION...
20/18Z TAF Period

Scattered to broken MVFR/low-VFR conditions will prevail through
00z Monday along and east of a KWYS, to KLWT, to KHVR line; with
increasing CIGS thereafter. The potential for fog development then
becomes the next concern, most notably over the plains terminals
of KHVR and KCTB where MVFR/low-VFR VIS is expected to develop
between 10-14z Monday. Additional fog development is possible
across Southwest Montana during this timeframe; however,
confidence was not high enough to prevail at this time. - Moldan

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  73  46  79  48 /   0   0   0   0
CTB  73  44  76  45 /   0   0   0   0
HLN  72  44  76  46 /   0   0   0   0
BZN  66  39  73  41 /  10   0   0   0
WYS  62  26  69  29 /  10   0   0   0
DLN  67  38  72  40 /   0   0   0   0
HVR  73  45  78  47 /  10   0   0   0
LWT  65  43  74  46 /  30  10   0   0

&&

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

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