515
FXUS65 KBYZ 131143
AFDBYZ

Area Forecast Discussion...Updated
National Weather Service Billings MT
543 AM MDT Sun Sep 13 2026

.KEY MESSAGES...

- Below average temperatures through the middle of next week.

- Chance of showers (mainly light) through Monday. Isolated
  thunderstorms possible in southeast Montana this evening and
  overnight, possibly strong.

- Brisk west winds Monday; gusts over 50 mph possible from Big
  Timber to Harlowton.

&&

.UPDATE...

Breezy conditions are still expected today across southeast MT
with the strongest southeast wind gusts reaching 35 to 45 mph this
evening. Some hi-res models are showing mountain wave activity
across the Beartooth foothills overnight tonight from around
midnight to 6 am MDT. There is some uncertainty on if stronger
winds just above the surface will make it down the mountain. At
this time, there is about a 30% chance for gusts to 50 mph in Red
Lodge.

&&

.DISCUSSION...

Next 7 days (Through Saturday)...

Short wave ridging today ahead of an approaching upper low over
the Pacific NW will lead to warmer and mainly dry conditions
across our CWA today. Highs will range from lower 70s to lower
80s. The pattern will also induce brisk southeast winds across our
eastern border counties with gusts 25 to 40 mph by the afternoon.
Models track the Pacific low eastward into the inter mountain
Rockies by evening with mid level flow backing strongly to the
southwest over our region.

As the low tracks across the region Sunday night into Monday, and
associated cold front pushes through our area, we should see
isolated to scattered showers and a few thunderstorms develop.
However, the best upper dynamics are progged to track north of our
CWA limiting potential rainfall. That said, there is a brief
window of decent CAPE and shear in our southeast corner (Carter
County) where CAMs are suggesting some convection. Instability is
limited, but we could see a strong cell or two in that area toward
mid to late evening. Snow showers are possible over the highest
elevations, though little in the way of accumulation is expected.

Behind the front, Monday will feature dry, cooler and breezy
conditions. Highs will be range from 60s west to around 70 east.
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
40-70% chance at seeing wind gusts of 50 mph or greater. Models
seems to be flip flopping on the strength of 700 mb winds, so have
held off on any wind highlites at this time, but will continue to
monitor the US-191 corridor (Big Timber to Judith Gap) for
Monday. As winds drop and skies clear out Monday night, frost is
possible (20-40% chance) for some of the colder valley locations.

Ensembles still signal NW to cyclonic flow behind the departing
upper low will keep temps a little cooler than normal through
midweek. Occasional shortwaves may bring a chance of light showers
to the area at times, most notably in the Thursday/Friday time
frame according to the ECMWF. However, ensembles are not in
agreement with this, so a good deal of uncertainty for now. Highs
are forecast to range from 60s to lower 70s through Wednesday.
Temperatures in the upper 60s to 70s are progged for Thursday and
Friday. We may see lows in the 30s for Monday night/Tuesday
morning with a slight chance of frost possible in the south
central MT foothills. Otherwise, lows will be mainly 40s to lower
50s this week. BT



.AVIATION...


A small chance for low clouds along the foothills remains through
around 15Z this morning. Breezy conditions are still expected for
locations east of Billings with southeast winds gusting 25-40 kts
(strongest this evening). Isolated thunderstorms are also possible
across southeast MT this evening likely producing gusty and
erratic winds and moderate rainfall. A cold front is expected to
move through the region this evening through the overnight hours
shifting winds to become northwesterly and bringing light
precipitation. Mountain wave activity can also be expected
overnight tonight between 06 and 12Z along the Beartooth
foothills. Currently, there is around a 30% chance for gusts to
50 mph at KRED during this time. TS


&&

.PRELIMINARY POINT TEMP/POPS...

    Tdy Mon     Tue     Wed     Thu     Fri     Sat
-------------------------------------------------------
BIL 079 050/067 042/071 047/068 045/075 049/075 048/080
    0/U 41/N    00/U    00/B    10/U    33/W    11/U
LVM 077 041/064 034/070 039/068 038/074 042/075 042/080
    0/N 41/N    00/U    01/U    11/U    33/W    11/U
HDN 083 045/070 038/074 041/071 040/076 043/077 042/081
    0/U 51/N    00/U    00/U    01/U    33/W    11/U
MLS 075 051/068 042/069 048/072 044/075 048/076 046/079
    0/N 24/W    00/U    10/B    01/U    23/W    32/W
4BQ 077 052/070 042/072 048/075 045/076 048/077 046/080
    0/U 23/W    00/U    00/U    12/W    43/W    32/W
BHK 073 048/069 038/069 042/075 041/075 044/077 042/079
    0/N 33/W    00/U    21/B    11/U    34/W    31/U
SHR 084 044/070 036/073 041/070 040/074 043/075 041/079
    0/B 21/N    00/U    00/U    12/W    33/W    22/W

&&

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

&&

$$
weather.gov/billings