921
FXUS65 KTFX 041121
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
Issued by National Weather Service Glasgow MT
421 AM MST Wed Nov 4 2026

Aviation Section Updated.

.KEY MESSAGES...

- A weak front will bring slightly cooler temperatures today,
  otherwise, generally milder and drier conditions prevail for
  much of the week.

- There may also be some patchy fog development tonight, mostly
  for the river valleys and higher southwest basins.

- Fast moving weather systems will bring periods of breezy to
  windy conditions and spotty mountain precipitation Thursday
  through early next week.

&&

.DISCUSSION...
/Issued Issued by National Weather Service Glasgow MT/

 - Meteorological Overview:

Ridging aloft will remain over the Northern Rockies for the next 24
hours, while a weak mid-level circulation moves eastward through
the Great Basin. A weak frontal passage will cool todays highs by
a few degrees and will bring some nighttime and early morning
patchy fog development, mostly over the north-central river
valleys and the higher southwest basins along the MT/ID/WY
borders.

An initial trough passage will bring increased westerly winds and spotty
mountain precipitation on Thursday. This will usher in an
extended period of strong westerly flow aloft that will persist
into early next week despite dominant ridging building for the
first half of the weekend. The trend of the strongest winds aloft
staying north of the Canadian border on Friday continues to gain
traction, but a tightening surface pressure gradient and mountain
wave activity still looks to enhance stronger winds along the
Rocky Mountain Front Friday into early Saturday.

Ensembles are favoring the ridge flattening and sending a fast
moving trough into the forecast area Sunday into Monday. This
will bring another round of winds, strongest along the Rocky
Mountain Front, and some more light precipitation along the
northern divide. Temperatures look to remain above average this
weekend into early next week, with only a slight cool down
following any shortwave passages. - RCG


 - Forecast Confidence & Scenarios:

Periods of stronger westerly winds Thursday through early next week

NBM probabilistic guidance continues to highlight Friday into
Saturday  for the strongest winds, with probabilities for 55 mph
wind gusts running 70 to 90% along the Rocky Mountain Front and
the plains along and west of highway 89 and along and west of I15
over Glacier County. The 40 to 60% chance for 75 mph wind gusts
remains confined to the immediate eastern slopes of the Northern
Rocky Mountain Front and will be heavily reliant on mountain wave
activity. The plains east of I15 also look windy during this time
as well, especially the central MT highway 87/200 corridor where
30 to 50 mph gusts will be common. The winds for Sunday into
Monday have slightly lower probabilities despite stronger winds
aloft, this looks to be mostly a trough timing issue. - RCG


&&

.AVIATION...
04/12Z TAF Period

Ridging aloft will maintain a light wind regime and primarily VFR
conditions; however, low status and patchy fog looks to bring
periods of MVFR/IFR/LIFR degradations at KWYS and to a lesser
degree KHVR. These conditions will be most prevalent during the 10
to 15Z period today and again on Thursday. - RCG

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  49  31  54  35 /   0   0   0   0
CTB  48  29  50  34 /   0   0   0   0
HLN  48  28  48  29 /   0   0   0   0
BZN  44  27  46  28 /   0   0   0  20
WYS  50  20  41  22 /   0   0   0  20
DLN  45  25  43  24 /   0   0   0  10
HVR  44  27  51  33 /   0   0   0   0
LWT  48  30  54  31 /   0   0   0   0

&&

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

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