251
FXUS65 KBYZ 060644
AFDBYZ

Area Forecast Discussion
National Weather Service Billings MT
1244 AM MDT Sun Sep 6 2026

.KEY MESSAGES...

- Increasing chance for showers and thundersorms this evening into
  Monday. Thunderstorms will be capable of producing heavy rain
  and gusty winds. Cannot rule out hail with discrete
  thunderstorms Today as well.

- Windy conditions are expected Monday into Tuesday (wind gusts of
  25 to 50 mph, strongest in south-central MT Monday and eastern
  MT Tuesday). This will cause elevated fire weather conditions.

- Drier and warmer conditions are likely during the middle of next
  week ahead of another potential weather system next weekend.

&&

.DISCUSSION...

Today through Saturday...

Isolated showers and a few rumbles of thunder are ongoing this
morning, mainly over southeastern Montana. The only concern with
this activity are brief wind gusts and a few lightning strikes.
Otherwise, patchy fog may develop in the lower valleys north and
east of Billings this morning, including locations near the
Dakotas Border.

An upper low continues to dig through the Pacific Northwest
today. Later this afternoon and evening, as this low moves
eastward the left exit region of the trough could bring isolated
to scattered shower and thunderstorm development to south and
central Montana. The Storm Prediction Center has a Marginal Risk
(level 1 out of 5) across much of Montana, for a few strong to
severe thunderstorms. The primary concerns are strong wind gusts,
heavy rainfall, and hail. Capping looks to be a problem though,
with HiRes models depicting a strong enough cap that hinders
convective development. The exception is far southeast Montana
where a surface low will exist and provide a forcing mechanism.

The low continues moving through Idaho this evening,
bringing a shortwave ahead of it. This wave will bring ample
forcing and a better chance of precipitation (up to 70 percent)
to south- central Montana into Monday. Look for showers and weak
thunderstorms overnight, before the chance for precipitation
generally comes to an end through Monday morning. Lingering
activity may still exist over the mountains and foothills west of
Billings as well as along the Dakotas Border.

The aforementioned low pressure system will move northeastward
through Montana on Monday. Isolated shower and thunderstorm
activity looks to accompany this during the day. The threat for
strong to severe thunderstorms will be very low. The main hazard
looks to be the synoptic winds associated with the low pressure
system. At this time, widespread wind gusts in the 20s to 40s mph
are forecast, strongest over the foothills west of Billings. Areas
around Livingston to Big Timber and Harlowton may even see a few
50 mph wind gusts late Monday (50 to 70 percent chance).

Tuesday, windy conditions look to continue across much of the
area, though the strongest winds will shift to be over far eastern
Montana. Again, wind gusts in the 20s to 40s mph are forecast to
be common, strongest to the north and east, with a few 50 mph wind
gusts possible around Baker, Montana (25 to 40 percent chance).

Wednesday into Friday are forecast to be mostly dry days as low
amplitude ridging nudges into the region aloft. By late Friday
into the weekend, the chance of precipitation returns, but
uncertainty remains regarding the upper level weather pattern.

LA/PM

.AVIATION...

06z TAF/Aviation Discussion...Elevated instability will exist
across the forecast area overnight through tomorrow. CAPE values
are over 1000 J/KG for areas east of Billings at 06z with steep
mid level lapse rates. The limiting factor for convection becoming
more widespread overnight into tomorrow is stable and fairly dry
lower levels (below 8-10kft AGL) and a lack of stronger forcing
mechanisms. The result is likely to be isolated high based
showers, maybe a tstm or two, spontaneously developing over the
eastern half of the forecast area through the morning hours.

Expect any convection to be light but there is really no focus for
this activity so be alert for development. Fog is also a
possibility overnight along the Lower Yellowstone and Tongue
river valleys (Forsyth/Miles City) and along the eastern state
line (Baker/Ekalaka) from 09z through 15z. Expect local IFR or
lower conditions where fog does manage to get established.

Outside of the above expect a mainly quiet weather period lasting
through the daytime hours tomorrow. Cold front and more widespread
convection, some strong, is forecast for tomorrow evening, lasting
overnight into Monday morning. Chambers
&&

.PRELIMINARY POINT TEMP/POPS...

    Tdy Mon     Tue     Wed     Thu     Fri     Sat
-------------------------------------------------------
BIL 086 061/080 054/075 049/081 053/087 055/079 051/066
    0/U 53/W    00/N    00/U    00/U    01/B    43/W
LVM 084 050/071 042/071 040/080 047/084 048/079 044/066
    0/U 64/T    10/N    00/U    00/N    12/T    44/W
HDN 089 058/085 050/077 045/082 046/088 049/081 047/068
    0/U 43/T    00/N    00/U    00/U    01/U    33/W
MLS 092 065/085 054/075 048/079 051/086 053/079 049/067
    1/U 43/W    10/N    00/U    00/U    01/U    42/W
4BQ 094 068/087 054/078 048/081 052/087 054/082 050/071
    0/U 52/T    30/U    00/U    00/U    00/U    32/W
BHK 096 063/088 050/077 044/080 047/087 050/081 045/070
    2/W 73/N    10/N    10/U    00/U    00/U    42/W
SHR 090 057/083 045/076 042/078 046/085 048/081 045/070
    0/U 31/B    00/U    00/U    00/U    00/U    33/W

&&

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

&&

$$
weather.gov/billings