286
FXUS65 KBYZ 042045
AFDBYZ

Area Forecast Discussion
National Weather Service Billings MT
145 PM MST Thu Dec 4 2025

.KEY MESSAGES...

- Gusty to locally strong winds (35-50mph) over the foothills west
  of Billings continue into tonight (Livingston, Nye, Big Timber,
  Harlowton).

- Periods of moderate to heavy snow in the mountains continue
  through Saturday. Total accumulations over a foot forecast,
  greatest on west and northwest facing slopes.

- Light precipitation possible (20-40% chance) tonight through
  Friday morning lower elevations. Mainly snow but could mix with
  rain through early this evening.

- Better precipitation chances (30-60%) arrive late Friday through
  Saturday. Increasing chances for mixed precipitation during
  this period has lowered potential snow accumulations, but could
  still make travel difficult in a few locations.

- Confidence is above average for warm and potentially very windy
  weather pattern for early next week.

&&

.DISCUSSION...

This afternoon through Wednesday...

No changes planned to current winter weather highlites for area
mountains with this forecast package.

Active weather pattern through the weekend as the area remains in
northwesterly flow on the western edge of a persistent trof. Waves
of energy dropping southwest into this trof are bringing glancing
blows of cold air into the area while aloft a fairly constant
stream of Pacific moisture provides moisture for precipitation
when these disturbances move through. One disturbance is beginning
to impact the area now and will bring a chance for mainly light
snow to the area tonight into tomorrow morning. Initially snow
potential will be more widespread from west to east as the system
moves through the area, but will subside southward into primarily
the Bighorn mountains and foothills going into tomorrow morning.
Probabilities for an inch or more of precipitation over the lower
elevations tonight into Friday morning are less than 10% for most
locations, but in those favored Bighorn foothills locations
probabilities increase to around 40% for the Wolf mountains and
the Aberdeen hill area. Mountains will see persistent light to
moderate snowfall through Friday with periods of heavier snow on
west facing slopes.

Tonights system exits the area tomorrow morning with a break in
precipitation chances for the lower elevations. The next
disturbance arrives by late afternoon/early evening, and this
system has stronger forcing associated with it. Yesterdays model
runs sagged the cold front this system pulls down from Canada
further south into our area than the current model runs do. As a
result the latest guidance is suggesting less snowfall for the
lower elevations. In fact, Friday night may see temperatures rise
above freezing in the middle of the night as an area of warmer air
pushes through in the low-mid levels. NBM shows snow Friday
evening turning to a mix of rain/snow and possibly some pockets of
freezing rain/sleet in the middle of the night before
transitioning back to snow around sunrise. This warm advection
scenario is dampening snow ratios and cutting snow accumulations
down significantly from yesterdays runs over central and eastern
areas, from 2 to 4 inches down to a Trace to 2 inches for areas
along and east of a Harlowton to Billings to Crow Agency line,
with probabilities for 2+ inches below 30%. Given this change not
planning on any winter highlites for the lower elevations for
Friday night-Saturday at this point, but will have to watch how
the mixed precipitation potential evolves over the next 24 hours.
For the mountains periods of moderate to heavy snow will continue
with probabilities of over a foot sitting at 60 to 80 percent in
the higher elevations of the Beartooth/Absaroka/Crazy mountains.
The heaviest accumulations will be on west and northwest facing
slopes.

Winds through the weekend...Gusty conditions have been ongoing
along the western foothills since sunrise this morning with a few
gusts over 50 mph being reported, and gusts as high as 40 mph
spreading as far east as eastern Golden Valley and Stillwater
counties. Expect winds to remain gusty over the western foothills
through the night tonight, with peak gusts dropping about 10 mph
from current peak values, closer to 40 mph. Another period of
gusts in the 50 mph range arrives Friday night as the stronger mid
level flow/warm advection pushes over the divide and strengthens
the gap wind ingredients there. The strength of the winds looks to
stay below wind highlite thresholds, but that will depend on the
disturbance and how far west the cold front makes it. If the front
drops further southwest than currently forecast winds could be
weaker, if it stays further northeast than currently forecast
winds could get closer to needing wind highlites. Winds should
weaken and become less impactful Saturday afternoon.

Extended forecast continues to trend warmer and mainly dry for
the lower elevations Sunday through Wednesday as a ridge develops
along the Pacific coast and pushes over the Northern Rockies.
Pacific moisture will continue to flow over the mountains through
this period producing fairly continuous but mainly light snowfall
for west facing mountain slopes, along with a good amount of daily
cloud cover. Downslope winds will push temperatures well above
average for much of the area by Tuesday with forecast highs in the
mid to upper 40s, a few lower 50s possible. Ridge flattens on
Wednesday with falling heights aloft and a more direct flow of
Pacific moisture flowing over the area, taking the edge off of
temperatures though still staying above normal for this time of
year. The potential exists for a prolonged period of strong winds
along the western foothills from late Sunday through Tuesday
night, which may push into the plains during the afternoon hours
Monday and Tuesday. Chambers

.AVIATION...

18z Discussion...

Strong west/southwest winds are forecast for KLVM/K6so through
the daytime hours today (through 00z). Gusts up to 45kts should be
expected. Winds at KBIL are forecast to be sustained around 15kts
out of the WSW with gusts up to 25-30kts.

The next round of wintry precipitation enters between 22-02z (NW-
SE) which will start as mixed precip and then transition to snow.
KBIL may be on the very edge of this rain/snow line and thus
frequent transitions back and forth after 06z should be expected.
Also note that if the wind direction changes a little off of the
forecast, the showers at KBIL may start as early as 00z.

VFR conditions wil prevail through 06z when lower VIS and CIGs are
possible. While most sites will likely prevail MVFR conditions,
IFR and LIFR conditions at any site could briefly occur. Mountains
will be partially to fully obscured for the entire period. WMR

&&

.PRELIMINARY POINT TEMP/POPS...

    Fri     Sat     Sun     Mon     Tue     Wed     Thu
-----------------------------------------------------------
BIL 027/037 026/037 022/040 030/043 032/047 031/041 031/043
    34/S    65/S    20/B    10/B    14/R    54/O    43/O
LVM 026/039 030/040 027/041 028/043 032/048 031/044 031/047
    78/S    85/S    21/B    20/N    25/R    55/O    43/O
HDN 026/037 022/035 017/040 024/043 027/046 027/040 026/043
    62/S    77/S    40/B    10/B    14/R    65/O    43/O
MLS 025/032 017/025 009/031 020/039 028/043 024/036 023/038
    41/E    64/S    40/B    10/B    24/R    43/O    42/O
4BQ 028/033 020/033 015/037 024/042 028/046 027/039 026/041
    42/S    33/S    31/B    00/B    13/O    53/O    32/O
BHK 021/031 010/025 003/030 017/038 023/040 019/032 017/033
    54/S    44/S    41/E    10/N    24/O    32/S    32/S
SHR 023/036 018/038 019/041 022/045 024/050 025/041 023/044
    65/S    55/S    30/B    10/B    13/R    64/O    43/O

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...Winter Storm Warning in effect until 2 PM MST Saturday FOR
      ZONES 67-68.
     Winter Weather Advisory in effect from 5 PM this afternoon to
      2 PM MST Friday FOR ZONE 171.
WY...None.

&&

$$
weather.gov/billings