Comanche, Montana Weather Forecast Discussion

569
FXUS65 KBYZ 041742
AFDBYZ
Area Forecast Discussion
National Weather Service Billings MT
1142 AM MDT Sat Oct 4 2025
.KEY MESSAGES...
- Strong weather system continues to impact region thru the
  weekend.
- Widespread precipitation thru Sunday, with significant mountain
  snowfall.
- High probability of a frost or freeze Sunday night.
- Dry with a warming trend next week.
&&
.DISCUSSION...
Through next Saturday...
Satellite imagery shows upper low in western WY with associated
deformation zones pushing into south central MT and NW WY. Strong
divergent flow was evident from east central WY into southern MT.
This was all indicative of the strong synoptic ascent across the
region as the upper low system pushed through the Rockies with
radar showing widespread precipitation over our CWA.
As the upper low to the south tracks across Wyoming and into
North Dakota tonight we will see strong deep N/NE upslope develop
over our area enhancing precipitation potential over and near north
facing slopes. In the meantime, additional energy drops south out
of Canada into western MT and Idaho. This feature bring us colder
air Sunday, lowering snow levels with some gusty NW winds
developing.
Much of the synoptic ascent will focus across our eastern zones
Sunday, while the other energy dropping through western MT and
Idaho produces additional ascent and reinforces upslope
precipitation across our western mountains and foothills. Snow
levels drop to near 5500 ft which should result in some snow in
the Beartooth and Red Lodge foothills. How much is still
uncertain, but an inch or two of wet snow cannot be ruled out for
the Red Lodge vicinity, though it would likely accumulate on
grassy surfaces and not impact roads much. Currently the chance
of at an inch or more in the Red Lodge vicinity is around 40%.
By Sunday evening, much of the precipitation tapers down as a
surface high settles over eastern Montana.
Overall, total precip of 0.50-1.50" are still expected for many
locations, with up to 2" in some southern upslope areas. The
probability of a half inch or more is 65-95% (lowest north), and
there is still a reasonable 20-50% chance of exceeding 1.50"
(greatest along southern foothills). This event should put an end
to our wildfire season.
Snowfall Totals...Mountain snowfall will be heaviest above 8kft,
but accumulations will drop to near 6kft. The probability of at
least 12" above 8kft is 60-80% over north aspects of the
Beartooth-Absarokas, and 30-50% over the Crazy, Pryor and Bighorn
Mountains. Foothills snow down to 5-6kft is a possibility, but
as already mentioned this is much more uncertain. We still do not
anticipate snow levels falling lower than 5kft, so places like
Livingston and Sheridan should not be impacted (though snow could
affect I-90 over Bozeman Pass tonight into Sunday).
Many locations could see a frost or freeze Sunday night,
especially over our western foothills and nearby lower elevations
and river valleys. However, the chance of a freeze/frost has
decreased a bit for areas east and south where cloud cover could
linger. Be sure to play it safe if you have sensitive outdoor
plants. Billings has a 30% chance of reaching 32F Sunday night,
but surrounding notoriously colder spots have better potential
(40% or higher).
Monday through Saturday: Ensembles and cluster analysis lends
strong confidence to a ridge building over the region for the
early part of the work week. The ridge axis slides east after
midweek with upper flow backing to the southwest as the next upper
trough drops into the Pacific NW. This should mean a generally
dry period and warming trend through the week. Look for temps in
the 50s Monday, 60s Tuesday, and mid 60s to mid 70s for the
remainder of the week. There could be a shortwave moving across
southern Canada that brings a bit of cooling by Thursday or
Friday, but ensembles indicate quite a bit of uncertainty
pertaining to this. Overall, the next best chance of measurable
precipitation looks like next weekend as the upper trough settles
over the western CONUS and intermountain region pushing Pacific
moisture into our area...and possibly some moisture associated
with a tropical storm which is expected to form off the SW coast
of Mexico over the next couple days. BT
.AVIATION...
18z Discussion...
Widespread rain is expected for most of the forecast period with
snow in the mountains. While CIGs and VIS are VFR at the current
time, expect both to lower to MVFR this afternoon across the
entire forecast area. Brief dips to IFR cannot be ruled out
through 12z as well. On the backside of this system, around 15z
KLVM may see some snow mix in with rain before tapering off
quickly after; all other sites will see no frozen precipitation.
Winds will turn gusty after 02z at KSHR gusting out of the NW up
to 30kts in the precipitation. Mountains will be obscured for the
entire period. WMR
&&
.PRELIMINARY POINT TEMP/POPS...
Tdy Sun     Mon     Tue     Wed     Thu     Fri
-------------------------------------------------------
BIL 054 042/050 034/057 037/065 041/071 044/070 041/071
    +/T +8/W    31/U    00/U    00/U    00/U    00/U
LVM 051 035/046 025/056 027/065 033/070 036/068 036/071
    +/R 89/W    30/U    00/U    00/U    00/U    11/U
HDN 057 041/052 032/057 031/066 034/072 038/070 036/071
    +/T +8/W    31/U    00/U    00/U    00/U    00/U
MLS 062 044/056 032/059 033/066 040/073 042/071 039/071
    9/T +5/W    10/U    00/U    00/U    00/U    00/U
4BQ 064 042/052 034/055 034/063 042/072 043/069 039/070
    6/T +9/W    21/B    00/U    00/U    00/U    00/U
BHK 066 041/055 030/057 032/065 039/072 041/071 037/069
    5/T +5/W    10/U    00/U    00/U    00/U    00/U
SHR 058 041/047 033/054 027/064 032/071 038/069 036/071
    9/T +9/W    61/B    00/U    00/U    00/U    00/U
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...Winter Storm Warning in effect until 6 PM MDT Sunday FOR
      ZONES 67-68.
     Winter Weather Advisory in effect from 6 PM this evening to
      midnight MDT Sunday night FOR ZONE 171.
WY...Winter Weather Advisory in effect from 6 PM this evening to
      midnight MDT Sunday night FOR ZONE 198.
&&
$$
weather.gov/billings

NWS BYZ Office Area Forecast Discussion