551
FXUS65 KTFX 131734
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
1034 AM MST Thu Nov 13 2025

Aviation Section Updated.

.KEY MESSAGES...

 - Breezy in most areas today, with strong gusts developing along the
   Rocky Mountain Front this afternoon into the overnight. Breezy
   winds persist into the day Friday.

 - Mainly light precipitation at times through Saturday, with areas
   in the mountains most favored for the light precipitation.

 - Trending a bit more active early next week.

&&

.UPDATE...
/Issued 853 AM MST Thu Nov 13 2025/

Current forecast remains on track through the day today. Current
mesoscale analysis shows the stronger 700mb winds moving in this
morning along the Rocky Montain Front. Breezy to gusty winds have
already begun to pick up along the immediate northern foothills.
I still anticipate peak winds (75 to 85 mph) to start there with
better vertical mixing this afternoon. Therefore, I kept the same
initial start time of the High Wind Warning at noon. However, we
will still monitor trends this morning as gusty winds begin to
pick up. -Wilson

&&

.DISCUSSION...
/Issued 853 AM MST Thu Nov 13 2025/

 - Meteorological Overview:

Upper level ridging across the interior west is beginning to exit
eastward early this morning as split Pacific troughing approaches
the west coast. The main lobe of vorticity with this trough will cut
off somewhere off the CA coastline through Saturday while the more
progressive, weaker portions of the trough continues eastward,
skirting along the Canadian border through Friday. The result for
today will be for another day of mild temperatures for most, with
precipitation confined to the Continental Divide north of Lincoln.

The higher impact weather for today will stem from a strengthening
pressure gradient and cross barrier flow along the Rocky Mountain
Front, beginning as early as late this morning along the Northern
Rocky Mountain Front. Forecast guidance continues to suggest a
mountain wave will set up along the immediate eastern slopes of the
Rocky Mountain Front this afternoon, bringing another period of very
strong wind gusts before moving off onto the adjacent plains late
afternoon into the evening. Given the combination of the increasing
pressure gradient this afternoon, cross barrier flow increasing
above 60 kts in most guidance through the afternoon, and favorable
mountain wave activity, the High Wind Watch was upgraded to a High
Wind Warning.

Breezy winds look to persist into the day Friday, but there is
uncertainty in how long they last, especially near the Canadian
border. A Canadian cold front dropping south has a non-zero
probability to undercut the warmer airmass and diminish surface
winds/gusts quickly, should it move in. For now the High Wind
Warning goes out through 5 PM Friday, though there is potential for
it to be canceled a bit early in some areas should that Canadian
front move through.

Weak shortwave ridging develops for Saturday, though lingering
moisture in a northwesterly flow will keep light, mainly mountain
precipitation around through the day. Heading into Saturday night
the cutoff low off the CA coast finally begins to lift northeastward
ahead of another Pacific trough well off the Pacific NW coastline.
Uncertainty is high for this timeframe, mainly associated with the
track of this upper level low (Quickly devolves into an open wave by
Sun AM). Should this upper low/open wave take a more easterly track,
the probability for meaningful precipitation would decrease and vice
versa. The key will be just how quickly the troughing across the
Pacific NW moves in and begins to influence the upper low off the CA
coast, which is low confidence at the moment.

Ensembles favor an active pattern next week, with the troughing
across the Pacific Northwest drifting eastward toward the Northern
Rockies into early next week. Confidence wanes in specifics, as
cluster guidance shows little consistency as to where the main
portion of the troughing will be by Tuesday. The common theme though
is that stronger troughs are further south, mainly near southern
CA/southern NV, and suggest another split troughing scenario.
Weaker, more broad troughing remains further north across the
Rockies, though is much quicker to progress eastward and exit. The
main takeaway is that temperatures look to fall at least a bit
closer to average early next week, with non-zero probabilities for
precipitation each day Monday through mid-week. -AM

 - Forecast Confidence & Scenarios:

Zonal to slightly southwesterly mid level flow will be on the
increase today along the Rocky Mountain Front. HREF 50th percentile
H7 flow by 2 PM today is in excess of 65 kts. In addition to the
risk of this mixing to the surface through the afternoon and evening
near the Rocky Mountain Front and adjacent plains, it will also help
in developing strong lee-side troughing through the afternoon and
evening, strengthening the pressure gradient. Add in favorable
thermodynamics later tonight for mountain wave activity and this all
result in a highly favorable situation for strong winds and gusts.

The portion of this forecast that is lower confidence is for a rogue
50+kt surface gust out around Cut Bank as daytime mixing is
maximized early this afternoon. Given this portion is lower
confidence, I held off from beginning the High Wind Warning this
early, but it will warrant monitoring for any late breaking changes
in confidence.

A High Wind Watch was considered for the Great Falls area east to
Geyser for late tonight into Friday morning. High-end guidance,
perhaps 20-30% or so, resulted in a period of stronger wind gusts as
the surface mixes out Friday morning. Given this low share of
guidance that is this aggressive, there was not enough confidence to
support a High Wind Watch at this time for these areas.


Northern Rocky Mountain Front snow tonight into Fri night:

Snow levels begin quite high with this system along the Northern
Rocky Mountain Front tonight, largely at or above 8,000ft. They do
fall through the overnight, but not quick enough to result in
impactful snow at Marias Pass. Hence, no Winter Weather Advisories
are being considered at this time for the overnight tonight into
Friday night. -AM

&&

.AVIATION...
13/18Z TAF Period

Winds will be on the increase across North Central and
Southwestern Montana as an area of increased mid and upper level
winds make their way into the area today. Expect winds to gust to
30 or 40 kts across the plains terminals this afternoon, with
gusts to 20 or 30 kts in the southwestern valleys. After sunset,
expect LLWS to increase in severity and areal coverage as surface
winds weaken (especially in the southwest valleys) even as winds
aloft continue to strengthen. A few light rain showers will be
possible late tonight and tomorrow morning, but VFR conditions
should prevail. Ludwig

The KWYS TAF will not be issued until airport operations resume
next spring.

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  67  52  60  43 /   0  10  30  10
CTB  63  43  52  30 /   0  20  40  20
HLN  65  46  58  40 /   0  30  60  20
BZN  65  41  60  35 /   0  10  50  20
WYS  52  31  46  28 /   0  20  80  30
DLN  61  39  57  32 /   0  30  40   0
HVR  67  46  59  28 /   0  10  30  20
LWT  66  47  60  35 /   0  10  30  20

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
High Wind Warning until 5 PM MST Friday for East Glacier Park
Region-Northern High Plains.

High Wind Warning from 3 PM this afternoon to 5 PM MST Friday
for Southern High Plains-Southern Rocky Mountain Front.

High Wind Warning from 5 PM this afternoon to 5 PM MST Friday
for Eastern Glacier, Western Toole, and Central Pondera.

&&

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