617
FXUS65 KBYZ 122304
AFDBYZ

Area Forecast Discussion
National Weather Service Billings MT
504 PM MDT Sat Sep 12 2026

.KEY MESSAGES...

- Below average temperatures through the middle of next week.

- Occasional chances of showers (mainly light) through Monday.
  Scattered thunderstorms possible in southeast Montana Sunday
  evening/night, some possibly strong.

- Breezy west winds Monday; gusts over 50 mph possible near Big
  Timber and Harlowton.

&&

.DISCUSSION...

Through next Friday...

Zonal to weak cyclonic flow was found over the region today as an
upper low approached the Pac NW, with shortwave ridging ahead of
the low over eastern WA/northern ID. Energy moving from west to
east through the area was producing a few light showers, mainly
over north and northeastern areas. Expect the showers to gradually
shift to the north and east through the afternoon. Easterly
upslope flow should allow stratus to fill back into the foothills
this evening, with patchy fog possible in the upslope area
overnight.

As the low tracks through the Pac NW, then north and east,
clipping NW MT, this will allow ridging to build over the area on
Sunday bringing a warmer and drier day. Breezy pre-frontal southwest
winds will work into the southwest mountains bringing elevated
fire weather conditions. Breezy southeast winds of 20 to 40 mph
can be expected over far southeast MT with lighter easterly winds
elsewhere. Heading into Sunday night, a cold front associated
with the low is progged to drop through the area bringing showers,
and a few thunderstorms to southeast areas. Snow showers are
possible over the highest elevations, though little in the way of
accumulation is expected. PWATs approaching an inch or more and a
very narrow corridor of elevated instability may allow for a
strong storm or two over the far southeast.

Behind the front, Monday will feature dry, cooler and breezy
conditions. Widespread westerly wind gusts of 30 to 50 mph can be
expected, with the greatest wind gusts along the western
foothills. Locations from Big Timber north to Judith Gap have
roughly a 40-60% chance at seeing wind gusts of 50 mph or greater.
Will continue to monitor, but have held off on any wind highlites
at this time as 700 mb winds reach 40 kts. As winds drop and
skies clear out Monday night, frost is possible (20-40% chance)
for some of the colder valley locations.

NW to cyclonic flow behind the departing low will keep temps a
little cooler than normal through midweek. Another shortwave
dropping out of western Canada brings a low chance (20% or less)
of light precip Tuesday night and Wednesday, mainly for the
periphery of the area, though there is uncertainty with the track
of the system. Yet another wave lifting in from the west and
southwest could bring additional chances for precipitation for the
Thursday/Friday timeframe (20-40% chance).

Highs are forecast to range from the 70s to lower 80s Sunday,
dropping into the 60s to lower 70s through Wednesday. Temperatures
in the upper 60s to 70s are progged for Thursday and Friday. Low
temperatures in the 40s to lower 50s can be expected most nights,
with some locations Monday night dropping into the 30s. STP

.AVIATION...

Upslope low clouds along the eastern slopes of the mountains are
expected to redevelop in some capacity tonight. Areas of MVFR
ceilings are possible west of KBIL, potentially impacting KLVM,
K6S0 & KHWQ. There is uncertainty here and this will be monitored.
Otherwise, VFR will prevail across the region through Sunday.
Expect E-SE winds to increase tomorrow with gusts of 25-35 knots
east of KBIL. JKL

&&

.PRELIMINARY POINT TEMP/POPS...

    Sun     Mon     Tue     Wed     Thu     Fri     Sat
-----------------------------------------------------------
BIL 046/077 050/068 044/070 047/068 046/075 050/077 050/079
    00/U    30/N    00/U    00/B    00/U    22/W    22/W
LVM 042/075 042/065 036/069 041/068 040/075 044/076 045/079
    00/N    51/N    00/U    01/B    00/U    22/T    21/U
HDN 042/082 045/071 040/073 041/070 041/076 042/078 042/081
    00/U    41/N    00/U    00/B    01/U    22/W    22/W
MLS 046/074 052/069 044/070 048/071 045/076 048/077 048/079
    00/N    51/N    00/U    20/B    00/U    22/W    22/W
4BQ 048/076 053/071 043/072 048/073 046/076 050/077 048/079
    00/N    31/N    00/U    10/U    01/B    33/W    22/W
BHK 041/071 049/070 039/070 043/073 041/076 045/078 045/079
    00/N    42/W    00/U    22/W    11/U    12/W    22/W
SHR 041/082 045/070 039/072 040/069 041/075 043/075 043/078
    00/U    30/N    00/U    00/U    11/U    33/W    22/W

&&

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

&&

$$
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