204
FXUS65 KBYZ 142008
AFDBYZ

Area Forecast Discussion
National Weather Service Billings MT
108 PM MST Thu Nov 14 2024

.KEY MESSAGES...

- Potential weather systems bring cooler and wetter conditions
  for Friday/Saturday and Monday/Tuesday.

- Strong winds look to return over the western mountains and
  foothills late Saturday into Sunday.

&&

.DISCUSSION...
Through Saturday...

Well-mixed westerly winds have become gusty across the lower
elevations, with gusts of 30-40 mph common as far east as the
Dakotas border. Steep low level lapse rates and 40 knots of mid
level wind support these winds continuing through mid afternoon,
but by sunset we should see speeds decreasing rapidly. Expect
light winds across the region by 03z (foothills breezes may
persist a bit longer).

Anticyclonic SW flow aloft between shortwaves will bring us dry
weather tonight through most of Friday, as a Pacific trof deepens
along the coast. A shortwave will emerge from this trof and lift
thru the great basin tomorrow, introducing a chance of light
precip in our west between 21-00z. This wave is our main feature
of interest for the remainder of the short-term period. Temps
Friday will be cooler than today, maxing out in the 40s to mid
50s.

Track of a mid level low (whether or not there will be a closed
circulation is of some uncertainty) thru northwest WY and into
southeast MT supports strongest ascent w/ upslope easterly winds
over our west, while there is dry-slotting from Sheridan through
far southeast MT initially (we would be talking about t-storms in
southeast MT if it was two months ago). As the low lifts into MT
and tracks to the northeast, precip associated with a weak trowal
will wrap into our central and eastern parts late tonight and
Saturday. Given this track, although the foothills/mountains will
see greatest precip amounts, our north/east will see some as well.
The EC and its ensembles continue to be a bit wetter than the GFS,
especially in the north, likely due to it supporting a bit
stronger and slower-moving low.

Mountains (esp. the Beartooth-Absarokas) should see on the order
of 4-8" of snow. The big issue for lower elevations is surface
temps as this is not a cold system. Precip should change to wet
snow by Friday evening in our west, and early Saturday in our
east. Western foothills should see a 1-3" snowfall (think
Melville, Emigrant, McLeod and Red Lodge). Remaining lower
elevations should see less than an inch, with the exception of the
higher hills (i.e. Bull Mountains, Hysham Hills, Wolf Mountains)
where amounts could reach 1-2". For Billings, it is going to snow
but will be tough to accumulate in the city (0.5" or less), while
the surrounding hills could see around an inch and at most two.

Look for drying from west to east across the area on Saturday as
heights build from the west. Any snow accumulation that falls
across west/central areas will likely melt quickly as temps warm
to the upper 30s and lower 40s.

A few notable probabilities:
0.25"+ of precip over western mountains & foothills:  70%
0.10"+ of precip:  60-90% from Rosebud Co westward
0.05" of precip from Sheridan to Alzada:  20-30%
6"+ of snow over the Beartooth-Absarokas:  50-70%
2"+ of snow at Red Lodge:  60%

JKL

Sunday through Thursday...

Monday through Tuesday will bring the first chance for
precipitation over the long term. Models are indicating a couple
troughs and associated low pressure systems that will impact the
region. The first, more northerly trough, will create a low
pressure system over Alberta and Saskatchewan that will bring a
cold front across the region. The second, potentially more
impactful trough, will dig down into Mexico before moving
northerly through the Great Plains. Some ensemble systems,
particularly the ENS and GEPS, are showing the potential for
precipitation from this system to wrap around and impact eastern
locations of the CWA along the Dakotas border. WPC clusters are
currently showing little agreement in how this system will play
out at the moment but it is something to keep an eye on.
Precipitation from these systems would likely start out as rain
for lower elevations and snow for higher elevations on Monday
before switching over to all snow Monday night after the passage
of the cold front. At this time precipitation from this event
looks to remain light with NBM giving the lower elevations a
30-50% chance of getting greater than 0.1 inches.

Temperatures Sunday will be in the high 40s to low 50s before
cooling into the 30s by Wednesday. By the middle of next week,
there is good agreement that some kind of upper ridging will make
its way into the region lifting temperatures into the 40s.

Winds will start to pick up in the western foothills and gap areas
Saturday night lasting through Sunday. Ensembles and
deterministic models are showing the potential for a Idaho Falls
to Lewistown pressure gradient in the 15-20mb range with 700mb
winds in the 25-30kt range. Given that this wind appears to be
mostly pressure gradient driven, local wind guidance is giving
Livingston significantly higher chances (85%) for strong winds
exceeding 58 mph than other locations. Strong winds will come to
an end Monday as the cold front passes through weakening the
pressure gradient. Torgerson

&&

.AVIATION...

Westerly wind gusts of 20-35 knots will decrease significantly by
sunset. Winds will be much lighter tonight and Friday. VFR will
prevail regionwide over the next 24 hours. By around mid afternoon
tomorrow, light rain/snow will begin to spread into the western
mountains, which will become obscured. JKL

&&

.PRELIMINARY POINT TEMP/POPS...

    Fri     Sat     Sun     Mon     Tue     Wed     Thu
-----------------------------------------------------------
BIL 028/046 032/043 027/048 032/044 025/039 019/039 022/046
    01/E    97/O    00/N    24/W    32/J    11/U    11/U
LVM 025/044 028/041 023/046 026/040 017/035 012/039 021/050
    04/O    +6/S    01/N    56/J    41/B    11/U    11/U
HDN 025/049 029/043 023/051 028/045 024/039 017/039 018/045
    00/E    8+/O    00/U    26/W    43/J    11/U    11/B
MLS 026/051 029/039 023/050 028/045 025/037 018/035 015/040
    00/E    3+/O    10/U    13/W    33/J    21/B    11/B
4BQ 028/052 028/039 023/053 027/045 025/036 019/033 016/040
    00/B    18/O    10/U    03/W    43/J    21/B    11/B
BHK 024/054 024/039 022/050 024/045 022/035 015/031 012/036
    00/E    18/O    30/U    02/W    33/J    21/B    11/B
SHR 024/050 028/043 019/055 026/045 020/036 017/039 015/048
    00/B    49/S    10/U    16/W    54/J    21/B    11/B

&&

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

&&

$$
weather.gov/billings