771
FXUS65 KBYZ 031136
AFDBYZ

Area Forecast Discussion
National Weather Service Billings MT
536 AM MDT Wed Sep 3 2025

.KEY MESSAGES...

- Cooler today with areas of smoke.

- Another cold front arrives Thursday bringing stronger northwest
  to north winds, gusting 30-45 mph (strongest east of Billings).

- A more significant surge of Canadian wildfire smoke is possible
  with Thursday`s front; be prepared for reduced visibility and
  poor air quality late Wednesday night and Thursday.

- Seasonably cool Thursday night to Saturday; frost possible in
  eastern sheltered valleys Friday night.

- Warmer with increasing chances of precip this weekend into next
  week.

&&

.DISCUSSION...

Through Thursday Night...

Satellite imagery shows a dry northerly flow over the region as a
Canadian clipper dives into the upper Mississippi Valley. There
were some light showers over our far east last evening but these
have shifted into the Dakotas. Boundary layer is undergoing steady
cold advection as winds have shifted to the NE most places. We`ve
been concerned about near surface smoke behind the fropa, and
while there is definitely some smoke around it is not dense, with
visibilities over the eastern plains ranging from 7-9SM as of 1am.
Do not feel that these visibilities will make a significant drop
through the early morning hours (based on upstream obs) but this
will be monitored. The backdooring winds will bring us cooler
temps today but not significantly so. In fact, our far western
foothills will see little impact with mixed W-NW winds anticipated
this afternoon and temps back to near 90F (and RHs in the teens).
Overall, look for highs today from the upper 60s near the Dakotas
to near 90F along the western foothills.

We will see the onset of pressure falls by this afternoon and this
will translate to lee side troffing tonight in advance of the next
Canadian clipper. In fact, we could see low temps realized in the
evening, before the warm advection and a little downslope wind
kick in. Today and tonight will be dry regionwide.

Next Canadian wave currently up in the Yukon will drop into the
northern plains tomorrow, and an associated cold front will arrive
by morning (cold advection ramps up in the 12-15z time frame).
Post-frontal/mixed NW winds will be gusty on Thursday and they
will begin relatively early in the day. Strongest 700mb winds
(around 50 knots) will exist over our east in the 12-18z time
frame, and we shouldn`t quite mix to that level by then.
Nonetheless we are looking at 30-40 knots in the mixed layer which
should easily translate to 35-45 mph gusts east of Billings.
Strongest winds will be near the Dakotas, perhaps up to 50 mph
from late morning to mid afternoon. Peak gust probabilities are as
follows:
40+ mph: 60-80% Baker-Ekalaka, 40-60% Forsyth-Sheridan-Miles City
50+ mph: 10-30% Baker-Ekalaka, near 0% further west

Not much precip associated with Thursday`s clipper, but model
soundings show a bit of mid level moisture and instability,
perhaps enough to produce light upslope showers along the southern
foothills in the afternoon.

Skies wil clear and winds decrease Thursday night as Canadian
surface high builds in. Temps in the 70s tomorrow will dip to the
upper 30s to mid 40s tomorrow night. If Billings airport reaches
its forecast low of 45F, it will be the coolest night since June.
A taste of fall indeed.

JKL

Friday through Tuesday...

Friday will be a cool and dry post-frontal day with highs in the
60s and 70s. Friday night into Saturday morning, temperatures look
to drop into the 30s and 40s across the area, coolest in far
eastern Montana where there is a 20 to 30 percent chance of seeing
a frost. As far as seeing a freeze goes in far eastern Montana,
probabilities remain low (less than 10 percent).

Saturday into Sunday will see heights gradually rise as low
amplitude ridging builds over the region. This will allow
temperatures to gradually warm back near normal by Sunday (highs
in the upper 70s to lower 80s). While Saturday looks to be a
mostly dry day outside of a slight chance of a weak shower or
thunderstorm over the mountains of south-central Montana, Sunday
will see a bit better chance of a weak shower or thunderstorm over
the mountains and foothills (20 to 65 percent chance) as
increased atmospheric moisture combines with weak energy aloft.
While a few showers or thunderstorms could move out over the
plains towards Billings, instability looks to drop quickly off the
mountains, limiting the activity over the plains. With this
activity on Sunday, precipitation amounts look to remain generally
light with the best chance of a wetting rain (0.10 inches) being
30 to 50 percent over the mountains of south- central Montana.

As we move into next week, a broad trough looks to move over the
west coast of the United States. This will allow winds aloft to
back out of the southwest over our region which will introduce a
daily chance of showers and thunderstorms to portions of the
region, best chances closer to mid-week. While there is no strong
signal for severe weather at this time, increased instability
mostly in eastern Montana Tuesday into mid-week may allow for a
few more robust thunderstorms to develop. Will have to see how
things trend. Temperatures during this time look to remain
seasonal. Arends

&&

.AVIATION...

An area of low stratus and perhaps some embedded fog over far
southeast MT will cause MVFR to local IFR until 15-17z this
morning. KBHK & K97M will be impacted by the lower ceilings.

Smoke concerns: Slight reductions to surface visibility, mainly at
or above 6SM, are expected today as NE winds advect wildfire
smoke over the plains of Montana. While improvements to surface
visibility are likely this afternoon and evening, another push of
more dense wildfire smoke looks to move into the region early
Thursday. This secondary push has a much better chance of reducing
surface visibility below 6SM, possibly to IFR. Just how far
remains uncertain at this time. Will continue to monitor. Other
than smoke, VFR will prevail regionwide through the period. JKL

&&

.PRELIMINARY POINT TEMP/POPS...

    Tdy Thu     Fri     Sat     Sun     Mon     Tue
-------------------------------------------------------
BIL 085 059/078 045/071 044/078 050/084 058/083 054/080
    0/K 00/N    00/U    00/U    01/B    12/T    22/T
LVM 090 053/079 040/074 039/080 049/080 048/078 047/076
    0/U 00/K    00/U    01/U    13/T    33/T    33/T
HDN 083 055/076 041/070 039/080 046/084 053/083 052/082
    0/K 00/N    00/U    00/U    00/B    11/B    22/T
MLS 075 054/074 042/068 039/073 046/083 053/084 054/081
    0/K 00/N    00/U    00/U    00/U    00/B    11/B
4BQ 074 054/074 042/065 038/072 047/081 056/081 054/079
    0/K 00/N    00/U    00/U    00/U    11/B    11/B
BHK 070 048/071 037/064 035/071 042/080 049/081 049/078
    0/K 00/N    00/U    00/U    00/U    00/B    11/B
SHR 082 053/078 038/069 037/077 045/081 050/080 049/079
    0/U 01/N    00/U    00/U    01/B    22/T    22/T

&&

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

&&

$$
weather.gov/billings