288
FXUS65 KBYZ 250806
AFDBYZ

Area Forecast Discussion
National Weather Service Billings MT
106 AM MST Mon Nov 25 2024

.KEY MESSAGES...

- Mostly dry today through Wednesday (a few light snow showers
  possible Tuesday).

- Occasional periods of light snow and colder air possible into
  the holiday weekend, but details are very uncertain at this
  time; monitor the forecast if you have travel plans!

&&

.DISCUSSION...

Today through Tuesday...

Building ridge from the west will bring dry conditions today and
tonight, but there are short-term impacts in the form of low
clouds and fog as cool surface high remains east of the mountains.
Temps have fallen to the single digits to mid teens, as expected,
but the boundary layer is moist and thus we are seeing pockets of
stratus and fog, especially west of Billings as noted on
satellite imagery. Livingston, Big Timber and Harlowton are
observing either low clouds or fog at 08z. Lee side pressures will
begin falling slowly before daybreak, resulting in developing SW
winds along the foothills. In fact, we are already seeing gusts
near 30 mph at Nye. Livingston will be trickier as the Yellowstone
valley is cold, colder than YNP, which will delay the onset of
downslope winds. When that does happen (should be early this
morning ~12z), there will be a short risk of blowing snow after a
couple inches fell yesterday. Gusts should exceed 30 mph (80%
chance). Temps will rise above freezing pretty fast along the
foothills, ending the BLSN risk.

Today will be warmer, but the snow cover and lack of a strong push
of downslope winds will keep locations east of the foothills slow
to moderate. High temps should range from the mid 20s in our
northeast (i.e. Baker & Miles City) to lower 40s along the
foothills. Billings will struggle to get to freezing.

Gusty SW winds will continue at the gap locations tonight into
Tuesday w/ persistent lee side trof and SW-W mid level winds of
25-30 knots. Gusts could reach 50 mph (50% chance) but should stay
below advisory criteria (10% chance of reaching 60 mph). Something
to watch.

Height falls associated with a shortwave dropping out of southern
BC will bring a low (15-30%) chance of light snow showers to our
west and north by Tuesday afternoon. Mid level lapse rates are
expected to be fairly steep (~7.5C/km) and surface temps should
warm to the mid 30s to mid 40s across the area. Western mountains
will see a little snow accumulation (around an inch). Gap winds
will diminish on Tuesday as the shortwave and cool advection
arrive.

JKL

Tuesday night through Monday...

Brief ridging through early Wednesday will give way to an
unsettled pattern with a cooling trend into the weekend. High
temperatures Wednesday will be in the upper 20s over the east to
upper 30s from Billings west. Then, highs on Thanksgiving are
expected in the low 20s over the east to low 30s over the west.
Highs on Friday look to be a couple degrees warmer than
Thanksgiving. For the weekend into early next week, models
diverge, although there is an increasing chance for Saturday to be
the coldest day of the week. Currently, there is a 30-60% chance
of highs below 20 from Billings east (best chance near the Dakota
border) on Saturday.

Late Wednesday into Thanksgiving morning has one of the best
chances for snow, with the highest chance (40-60%) from
Musselshell to Rosebud county. At this time, any accumulations are
expected to remain light, with only a 10-30% chance of more than
1 inch of snow. Then, early Friday through Saturday morning, there
is a 15-40% (lowest over the east) chance of at least an inch of
snow for most of the region. At this time, the rest of the weekend
into Monday look to remain mostly dry. Archer

&&

.AVIATION...

Complex flight category picture across the region through early
this morning. VFR exists most places, but localized IFR to VLIFR
in stratus/fog is impacting parts of the west...and this will
continue til 15-18z, with potential impacts west of Rosebud
County. Expect winds along the immediate foothills of the
Beartooth-Absarokas to pick up early this morning, resulting in a
risk of BLSN at KLVM beginning around 13z and persisting until
noon when temps rise above freezing. Expect 30-40 knot gusts at
KLVM today and tonight. Otherwise, VFR will prevail regionwide
this afternoon thru tonight. JKL

&&

.PRELIMINARY POINT TEMP/POPS...

    Tdy Tue     Wed     Thu     Fri     Sat     Sun
-------------------------------------------------------
BIL 032 021/042 021/038 018/029 015/030 010/021 007/026
    0/U 02/J    20/U    33/S    23/S    31/E    00/B
LVM 041 028/042 022/038 019/038 021/037 015/033 015/039
    0/Q 02/J    20/B    12/S    12/S    31/E    10/B
HDN 032 016/042 019/037 015/029 012/029 007/021 003/025
    0/U 01/B    31/B    44/S    23/S    43/S    11/B
MLS 026 011/037 013/030 011/022 006/022 003/016 903/017
    0/U 00/B    10/B    42/S    13/S    21/B    00/B
4BQ 033 014/043 019/033 016/028 011/029 007/020 003/024
    0/U 00/B    10/B    32/S    12/S    21/B    00/B
BHK 023 008/037 009/027 006/021 000/021 901/016 905/019
    0/U 00/B    10/B    21/B    12/S    21/B    00/B
SHR 038 014/042 018/038 013/033 011/035 008/026 005/032
    0/U 01/B    31/B    33/S    12/S    32/S    10/B

&&

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

&&

$$
weather.gov/billings