093
FXUS65 KBYZ 091047
AFDBYZ

Area Forecast Discussion
National Weather Service Billings MT
347 AM MST Thu Jan 9 2025

.KEY MESSAGES...

- Strong wind in the foothills Friday into Friday night (Chance
  of gusts over 50 mph near 100%). Impacts over I-90 Livingston -
  Big Timber, US-191 Big Timber - Judith Gap.

- Above normal temps through Friday, slowly cooling some over the
  weekend.

- Active weather pattern this weekend. Periods of snow showers
  with significant snow possibly piling up east/southeast of
  Billings through the weekend (Chance of 8+ inches 60-80% area
  between Aberdeen and Lame Deer).

&&

.DISCUSSION...
Today through Friday Night...

A shortwave trough is exiting to the southeast in the early
morning hours. Snow showers on radar are slowly winding down, but
will likely linger over the higher north facing mountain slopes
through early morning. Surface winds are still brisk, but there
is little indication of reduced visibility anywhere. Therefore,
the winter weather advisories have been cancelled. However, brisk
NW winds will continue along the eastern borders today as well as
Sheridan County with gusts 30-40 mph at times. Wind chills may be
in the single digits this morning in the far eastern zones.

Look for drier air and slowly building 500 mb heights from the
west today. Highs will range from mid 30s west to upper 20s east.

The next weather feature of concern is another round of wind for
the foothills and nearby plains. As high pressure aloft builds in
and lee-side surface pressure falls occur with some warming
(chinook pattern) we will see pressure gradients tighten over our
western foothills. This pattern favors the Big Timber vicinity the
most and the US-191 corridor to Judith Gap, but as usual,
Livingston will also see strong W/SW winds. We anticipate winds
picking up tonight into Friday, and continuing strong through at
least Friday evening. The chance of gusts above 50 mph is nearly
100% at Livingston, Big Timber, and Harlowton Friday into Friday
evening. Westerly gusts 30-40 mph may also affect areas as far
east as Billings by Friday afternoon as well. Windy conditions may
continue into Saturday from Big Timber to Harlowton.

Look for the downslope winds to warm temps into the lower 40s in
the foothills to 30s elsewhere for Friday. This will alleviate any
risk of blowing snow this time around.

Another short wave trough then drops into the area from the
north/northwest later Friday night, which will weaken winds and
bring a chance of snow showers as it moves through. Best chance of
accumulating snow Friday night is over the mountains, but
additional snow showers will affect the lower elevations this
weekend with a series of short waves moving through (see long term
discussion). BT


Saturday through Thursday...

Saturday into Sunday will be our next impactful system as a trough
moves in from our NW. While areas to the NW of Billings will not
see more than an inch total, areas towards Lodge Grass and the
Wolf Mountains could pick up a decent amount of snow by Monday.
The latest model runs are fairly similar, if not trending upwards,
compared to the last runs when it comes to the total
accumulations. The latest NBM is giving the US-212 corridor from
Crow Agency to just west of Broadus nearly a 75% chance of at
least 5" of snow throughout the weekend. These accumulations will
have a fairly sharp gradient as we look back towards Billings
where we only have a 40% chance of greater than an inch total.
Gusty winds are expected to spread across the entire CWA on
Saturday with widespread gusts to 25mph. Gap areas could push a
little higher. It will likely be more of a Big Timber / Harlowton
event as both 700mb and SFC winds will be out of the WNW during
the day Saturday. Additionally, 700mb winds are forecast to be
around 50-60kts with fairly steep low level lapse rates, so I
would not be surprised to have a gust that overachieves the
current forecast.

Looking ahead to next week, some of models have a little piece of
energy quickly rotating around a parent low centered in western
ON midday Monday. If this materializes, all it would likely do
would be enhance the exiting weekend system for a few hours in our
SE and provide an additional inch of snow. We then get put under
positively tilted ridge thanks to a cutoff low setting up over
the SW CONUS which should bring us relatively quiet weather mid-
week, with the exception of maybe some gap winds. Towards the end
of next week we may see a small disturbance riding along the
ridge Thursday before our next big weather maker moves in next
Friday.
WMR


&&

.AVIATION...

All precipitation has largely exited southeast Montana and
northern Wyoming with the exception of the mountains. Widespread
VFR conditions are expected throughout the period with gusty
winds (up to 30kts) from the west. Areas in the foothills,
including KLVM could see gusts to 40kts towards the very end of
the TAF period. Mountains will be obscured through 20z due to
lingering snow showers. WMR

&&

.PRELIMINARY POINT TEMP/POPS...

    Tdy Fri     Sat     Sun     Mon     Tue     Wed
-------------------------------------------------------
BIL 035 018/036 030/036 026/033 021/032 017/033 022/038
    0/U 00/N    25/J    66/J    52/J    10/B    00/U
LVM 034 021/041 027/033 022/032 018/032 016/037 025/044
    0/B 01/N    37/J    43/J    21/B    00/U    00/B
HDN 035 011/038 029/037 026/032 019/033 014/035 018/037
    1/U 01/B    58/J    99/J    74/S    11/B    01/B
MLS 030 011/036 029/033 017/023 009/025 012/031 019/033
    0/U 00/B    49/J    96/J    42/J    11/B    00/B
4BQ 031 013/037 030/034 021/027 014/028 015/033 021/036
    0/B 00/B    39/J    +8/J    63/S    11/B    00/U
BHK 028 009/034 026/033 009/017 902/021 010/029 016/033
    0/N 00/B    58/J    93/J    21/B    00/Q    00/Q
SHR 034 011/043 025/034 021/031 016/031 011/038 019/043
    1/N 00/B    68/J    98/J    74/S    11/B    00/U

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...None.
WY...None.

&&

$$
weather.gov/billings