059
FXUS65 KTFX 070537
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
1037 PM MST Sat Dec 6 2025

Aviation Section Updated.

.KEY MESSAGES...

 - Areas of snow or snow showers decrease this evening.

 - Temperatures warm above seasonal averages Monday and Tuesday.

 - Very windy conditions are likely Monday and Tuesday.

 - Mountain snow redevelops Monday and Tuesday with additional
   opportunities for mountain and lower elevation snow late next
   week.

&&

.UPDATE...
/Issued 815 PM MST Sat Dec 6 2025/

A warm front is slowly progressing northeastward through the
plains this evening. Once the front passes, the patchy fog and low
stratus clouds will dissipate in favor of warming temperatures
and increasing west/southwesterly winds. There will be some light
snow over the eastern portions of central/north- central MT this
evening before the warmer conditions move in later tonight into
Sunday morning. The winter weather advisories along the Rocky
Mountain Front and the Madison/Gallatin ranges will be allowed to
expire at 9 pm. - RCG

&&

.DISCUSSION...
/Issued 815 PM MST Sat Dec 6 2025/

 - Meteorological Overview:

Fast and moist west-northweerly flow from the Pacific continues
across the Northern Rockies and MT, maintaining a very active
weather pattern for the region through much of the week ahead. A
few areas of mainly light snow across eastern portions of north-
central MT should decrease through the rest of this afternoon but
may redevelop this evening, mainly along and east of a Havre to
Lewistown line as another wave of moisture overruns the deeper
cold airmass situated there. Orographically driven snow showers
continue to affect the mountains through this evening with areas
along the continental divide north of Lincoln and the Madison/Gallatin
ranges most likely to see additional accumulations of 2 to 4
inches while most other mountain areas can expect around 1 inch or
less from additional snow showers through this evening.
Temperatures will be tricky tonight across the north-central MT
plains as the low level cold airmass that moved in this morning
retreats back to the northeast overnight. Minimum temps are likely
to occur early this evening before rising overnight for areas
adjacent to the Rocky Mtn Front and east across Great Falls to
Lewistown.

A relative lull in between disturbances embedded within the fast
WNW flow aloft will bring mainly dry conditions with seasonal to
somewhat above average temperatures across the entire forecast
area Sunday. Mild and increasingly windy conditions are expected
Sunday night through Tuesday as upper ridging attempts to build to
our southwest with a stronger mid level shortwave and potent
upper level jet streaking east along the US/Canadian border late
Monday through Tuesday. This results very strong mid level flow of
70kts or higher above 10000ft which looks to peak early Tuesday
morning as surface low pressure tracks east across southern AB and
SK. Temperatures will warm to upper 40s to around 50 for most
lower elevation locations Monday and Tuesday with windier
locations seeing overnight temps remain above freezing.
Precipitation redevelops along the continental divide Sunday night
and will likely intensify Monday night as the upper level wave
passes. Snow levels initially around 5000ft look to rise to around
6500 ft Monday and Monday night before lowering again on Tuesday.

Additional disturbances move through the fast flow aloft Wed/Thu
with decreasing confidence in timing and details. Models ensembles
are increasingly supporting the idea that the upper level jet
sinks south with these features allowing a colder airmass to move
back southward by Thursday or Friday. Embedded moisture with these
disturbances could bring a period of prolonged mountain snowfall
as well as some opportunities for lower elevation snow. Hoenisch

 - Forecast Confidence & Scenarios:

The risk for a widespread wind event late Monday through early
Tuesday has increased with most deterministic models showing 700 MB
flow of 75-85kts with the passage of the wave early Tuesday morning.
Timing of the peak mid level wind speeds is not optimal for surfacing
strong winds and temperature profiles will be key to assessing the
potential for mountain wave enhancement, but probabilities for gusts
of 60 mph or more are better than 50-60% for areas along the Rocky
Mtn Front and adjacent plains as well as across portions of Cascade
and Judith Basin counties.

Snow with the Mon/Tues system is focused across areas near the
continental divide with rising snow levels likely to keep significant
accumulation above most mountain passes. Hoenisch

&&

.AVIATION...
07/06Z TAF Period

Initial concern this TAF period will be for some lingering fog
around Cut Bank as well as some light snow in the Havre area. Both
of these should diminish later tonight. Additional snow showers are
attempting to cross the Continental Divide this evening, but have
found little success thus far. Otherwise the primary concern through
the rest of the night and into the day Sunday will be for increasing
surface winds. Some LLWS will be around in areas over the plains
where surface winds are slow to increase tonight. -AM

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  21  41  36  47 /  20  10   0  10
CTB  11  37  28  41 /  10   0   0  10
HLN  29  41  32  46 /  30  20  20  20
BZN  23  39  27  45 /  40  10  10  10
WYS  14  30  21  34 /  50  60  70  60
DLN  25  39  28  44 /  10  10  10  10
HVR   6  36  24  41 /  80   0  10   0
LWT  18  38  27  43 /  60   0  10   0

&&

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

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