640
FXUS65 KBYZ 242331
AFDBYZ

Area Forecast Discussion...Updated
National Weather Service Billings MT
431 PM MST Sun Nov 24 2024

.KEY MESSAGES...

- Mostly dry Monday through Wednesday.

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

&&

.DISCUSSION...
Tonight through Monday night...

All winter weather highlights have been cancelled.

Positively tilted upper trough axis has shifted across much of
the area and weakened. Radar and surface observations indicate
only some lingering light snow from Sheridan County to southeast
MT. Snowfall occurred pretty much as expected with 1-2 inches
common along I-90 and southward to the foothills. The highest
amounts reported were near Big Timber (3.9 ins). We recorded 1.5
ins here at our office on southwest side of Billings, with a few
reports in Billings Heights and airport up to 3 inches.

Surface high will settle over eastern MT tonight with decreasing
clouds. Overnight lows will likely be the coldest of the season so
far with readings in the single digits to lower teens. We adjusted
guidance down where we have fresh snow cover.

Building ridge will bring dry and modestly warmer conditions
Monday. Westerly flow in mid levels will induce lee side
pressure falls over eastern MT leading to elevated winds along
the foothills (Livingston gusts 30-40 mph). Look for highs in the
mid 20s in our northeast (Baker) to lower 40s along the foothills
(Livingston). BT



Tuesday through Sunday...

The extended forecast period looks to have generally unsettled
weather with cooler temperatures. Models continue to disagree on
much of the details, though they are in better agreement that cool
temperatures with periods of light snow showers into Friday.

A brief ridge will build over the region Tuesday into Wednesday
resulting in high temps in the 30s to low 40s. A weak trough will
drop into the region, Wednesday, bringing NW flow and potentially
unsettled weather into the weekend. The chance for precipitation
is low to moderate (15-70%) Tuesday into Friday, with the best
chance in the central and western areas. Light snow showers will
bring the minor accumulations across the area, with lower
elevations seeing less than an inch during the week. The
probability of an inch Wednesday through Thanksgiving is less than
25% for the central part of the forecast area, though there is a
30-40% for much of Big Horn County.

Models diverge going into the weekend, with the GFS depicting a
developing trough over the Northern Plains. The ECMWF shows more
of NW flow with moisture running through it. There is still too
much uncertainty at this time with regards to this portion of the
forecast, though it will be worth monitoring.

The current forecast has high temperatures in the 20s to low 30s,
Thanksgiving Day through the weekend. Overnight temperatures will
drop into the single digits and teens as well.

Matos
&&

.AVIATION...

00Z TAF Update...Snow has ended and clouds are clearing from
west to east, with mainly SE MT continuing to see any MVFR
ceilings. Expect VFR conditions this evening. After 05-06z models
are suggesting fog development under a fairly deep boundary layer.
That said with clearing skies and fresh snow in many areas any
available moisture may deposit on the snow limiting fog potential.
TAFs all have VCFG in with a non-ceiling stratus deck associated.
If fog develops it could be locally dense (IFR/LIFR) so will be
monitoring this closely. Models also suggest that winds will
increase over the western foothills around sunrise with gusts
strong enough(gusts 20 to 30Kts) to blow snow around. Have an
initial blowing snow group in for KLVM starting at 14z. If blowing
snow does develop it will likely be confined to the morning hours
as temperatures should rise above freezing by mid day. Chambers
&&

.PRELIMINARY POINT TEMP/POPS...

    Mon     Tue     Wed     Thu     Fri     Sat     Sun
-----------------------------------------------------------
BIL 009/035 021/041 023/039 017/028 015/033 015/030 012/033
    00/U    01/B    21/B    33/S    23/S    32/S    01/B
LVM 012/042 023/043 022/038 018/036 018/038 016/037 017/042
    00/U    02/S    21/B    22/S    22/S    31/B    00/B
HDN 009/034 015/042 019/038 014/027 011/031 011/028 007/031
    00/U    01/B    31/B    44/S    23/S    43/S    11/B
MLS 007/028 011/038 014/031 010/022 007/025 007/022 001/024
    00/U    00/B    10/B    32/S    12/S    21/B    01/B
4BQ 009/034 014/043 019/035 014/025 010/030 011/026 006/031
    00/U    00/B    10/B    22/S    01/B    21/B    00/B
BHK 002/027 007/036 010/030 005/020 000/024 003/022 902/025
    00/U    00/B    20/B    12/S    02/S    21/B    00/B
SHR 008/038 014/044 019/039 014/031 010/036 011/032 009/037
    10/U    01/B    41/B    33/S    12/S    42/S    01/B

&&

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

&&

$$
weather.gov/billings