231
FXUS65 KTFX 090547
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
1047 PM MST Mon Dec 8 2025

Aviation Section Updated.

.KEY MESSAGES...

 - Strong winds develop and become widespread across much of
   north-central and southwest Montana tonight through Tuesday
   morning.

 - Widespread above normal temperatures continue through Wednesday.

 - Precipitation is mainly focused along the continental divide through
   Tuesday where snow levels fluctuate at or above 6000 ft.

 - Precipitation and the potential for accumulating snowfall
   becomes more widespread across north-central Montana later
   this week as a colder airmass also moves back south into the
   region.

&&

.UPDATE...
/Issued 850 PM MST Mon Dec 8 2025/

Cross barrier H700 flow in excess of 75 kts will continue to move
through the Northern Rockies tonight into Tuesday. After a brief
lull, winds along the Rocky Mountain Front and adjacent plains
west of I15 have increased significantly over the last hour.
Winds will continue increasing and will move eastward and deeper
into the plains by Tuesday morning. Wind gusts will mostly remain
in the 50 to 75 mph range with gusts over 80 mph at times along
the Rocky Mountain Front and the plains west of I15. Those
traveling with high profile vehicles or towing light weight
trailers in and near the areas with gusts exceeding 75 mph should
consider delaying travel. This includes highway 287 north of
Bowman`s Corner, highway 89 along the Rocky Mountain Front, and
the stretch of highway 191 near Judith Gap. No updating is
necessary this evening, but the high wind warning statements were
freshened per current trends. - RCG

&&

.DISCUSSION...
/Issued 850 PM MST Mon Dec 8 2025/

 - Meteorological Overview:

A very active weather pattern continues through the week as a strong
westerly flow and plume of deep Pacific moisture remains oriented
across the Northern Rockies and MT with embedded disturbances
bringing multiple rounds of precipitation, initially focused along the
continental divide, but expanding further east across central and
north-central MT later this week. Meanwhile, mild Pacific air will
maintain above average temperatures and relatively high snow-levels
through the next few days before a much colder airmass surges back
south into north-central MT later this week.

Mid-level westerly flow increases further tonight as a shortwave
disturbance rapidly translates east from BC to AB with surface low
pressure emerging in southern AB and tracking across southern SK
Tuesday morning. Strong winds re-intensify this evening along the
Rocky Mtn Front with the arrival of 70-80kt 700mb winds and spread
east across north-central and central MT overnight tonight through
Tuesday morning. Temperatures will remain mild tonight with many
lower elevation areas seeing steady temperatures in the 40s as winds
increase and thick cloud-cover persists. Precipitation remains mainly
confined to areas along the continental divide through Tuesday
morning where snow levels currently around 6000 ft rise to 7000 ft
or more overnight, limiting any impactful snowfall to the highest
terrain above passes.

Winds shift more northwesterly on Tuesday behind the surface low
across eastern portions portions of north-central MT with enough
cooling aloft and weak instability present to support some
convective shower development, mainly across Hill/Blaine/Fergus
counties. Temperatures cool just enough in these areas Tuesday
afternoon to support snow or a mix of rain/snow with main impact
being brief visibility reduction in these showers.

Another embedded shortwave moves across the Northern Rockies
Wednesday with snow levels remaining high along the continental
divide where the bulk of the precipitation occurs, while a period
of lighter rain/snow shifts across the plains early Wednesday
before westerly flow spreads mild but windy conditions back east
across the area.

A colder airmass begins to spread back south into north-central MT
Wednesday night through Thursday with the colder air lingering
through at least Saturday morning before retreating back north.
Meanwhile, additional shortwave disturbance move across the region
with an east west frontal zone aloft becoming a focus for
precipitation Thursday and Friday. Latest model guidance trends
are supporting the potential for several inches of snow
accumulation across portions of north-central and central MT
Thursday and Friday with still a fair amount of uncertainty in
specific amounts. Hoenisch

 - Forecast Confidence & Scenarios:

Ingredients for mountain wave enhancement are focused mainly along
the Rocky Mountain Front this evening, shifting to areas adjacent to
the Little Belts across Judith Basin county late tonight through
Tuesday morning. Wind gusts in excess of 75 mph are likely along the
Rocky Mtn Front with a 30-40% chance of wind gusts reaching this
magnitude across Judith Basin County, where winds of this magnitude
are not as frequent and may be more impactful than those along the
Rocky Mtn Front.

The arrival of colder air later this week has seen some fluctuations
in timing with still considerable uncertainty in how far south the
cold air will penetrate beyond central MT. Most model guidance keeps
the colder airmass limited to the plains. By Friday it is
possible that locations on the plains see afternoon temperatures
in the single digits while southwest MT valley locations remain
above average with afternoon temperatures in the 40s. Hoenisch

&&

.AVIATION...
09/06Z TAF Period

The primary concern this TAF period will be for strong surface winds
and gusts across the region. In areas where surface winds are
lighter, low-level wind shear will be a concern. Widespread mountain
wave turbulence is forecast, especially through the overnight.

Ample moisture streaming in across the Continental Divide will at
the very least obscure mountains, and may result in precipitation
further east at times. VFR conditions are favored overall, with
brief instances of MVFR not out of the question. -AM

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  42  50  33  54 /  20  50  60  70
CTB  38  43  25  44 /  30  40  30  40
HLN  40  48  33  52 /  50  70  80  80
BZN  36  47  30  54 /  20  50  70  80
WYS  25  39  26  41 /  80  90  90  90
DLN  38  48  33  53 /  30  50  70  50
HVR  31  45  20  41 /  40  70  20  80
LWT  34  46  24  48 /  30  70  40  90

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
High Wind Warning until 10 AM MST Tuesday for Cascade County
below 5000ft-East Glacier Park Region-Eastern Glacier, Western
Toole, and Central Pondera-Eastern Pondera and Eastern Teton-
Eastern Toole and Liberty-Gates of the Mountains-Madison River
Valley-Northern High Plains-Southern High Plains-Southern Rocky
Mountain Front-Upper Blackfoot and MacDonald Pass.

High Wind Warning until 3 PM MST Tuesday for Bears Paw Mountains
and Southern Blaine-Big Belt, Bridger and Castle Mountains-
Fergus County below 4500ft-Hill County-Judith Basin County and
Judith Gap-Little Belt and Highwood Mountains-Meagher County
Valleys-Northern Blaine County-Snowy and Judith Mountains-
Western and Central Chouteau County.

&&

$$
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