382
FXUS65 KBYZ 301148
AFDBYZ

Area Forecast Discussion
National Weather Service Billings MT
548 AM MDT Sat Aug 30 2025

.KEY MESSAGES...

- For today, expect isolated showers and thunderstorms west, and
  scattered showers and thunderstorms east. Locally heavy rain
  possible mainly east of Billings.

- Warmer and dry Sunday, Monday, and most of Tuesday.

- Late Tuesday cold front brings cooler temps Wednesday and
  Thursday, but mostly dry weather continues.

&&

.DISCUSSION...

Through Sunday Night...

Satellite imagery shows a weak shortwave moving thru south central
MT and northwest WY, a feature that in combination with steep mid
level lapse rates has been producing an area of showers and
t-storms over the Beartooth-Absaroka Mountains and adjacent
foothills since late evening. There has been scattered wetting
rains in this area, including 0.34" at Springdale. Radar shows a
decreasing trend now, which makes sense as the wave moves into a
region of less instability. Further east, there remain scattered
showers from northern Rosebud and western Custer into Powder River
Counties. Mid level convergence has nearly stagnated in this area
thus the continued light showers. No sign of fog yet, as of 0730Z,
but dew point depressions are low and winds are light, so could be
localized fog develop between now and sunrise where there are
cloud breaks.

Over time today, trof along the MT/WY state line will move east
and form into a weak mid level low over SD/NE, as heights start
to build over our west. Thus, expect the air mass to become drier
over west/central parts, while convergent easterly winds and
higher pwats remain over our east allowing further development of
showers and embedded weak t-storms. CAMs continue to show at
least isolated activity developing this afternoon west of Rosebud
County, and this seems reasonable given the boundary layer
moisture that has been established from recent precip (model
soundings show achievable convective temps). So in a general
sense, look for isolated (west) to scattered (east) showers and a
few t-storms today into the early evening. If there is an area to
watch for heavy rain it seems to be along the eastern convergent
axis which will continue to evolve slowly. Some showers may linger
in our far east through the night. Fog and stratus are possible
late tonight into early Sunday over Fallon & Carter Counties where
east winds will persist, but mid clouds and precip may be factor.

Sunday will be warmer & drier regionwide, as an upper level ridge
establishes itself. Lingering PV axis over our far east may allow
for a few showers to develop near the Dakotas border in the
afternoon, but there is considerable uncertainty here. Sunday
night will be dry.

Look for temps in the 70s to lower 80s today, rising to the upper
70s to upper 80s Sunday.

JKL

Monday through Saturday...

Monday will remain hot and dry under an upper level ridge, with
high temperatures generally in the mid to upper 80s.

Through the day on Tuesday, upper level flow will shift towards
NW/NNW, bringing a renewed push of moisture into the region, with
PWATs around 110-130% of normal. Coupled with a cold front
dropping through the region, there is a 20-40% chance of showers
and thunderstorms late Tuesday into early Wednesday.

Highs on Wednesday will be around 5-10 degrees cooler than
Monday and Tuesday, in the 70s for most locations. With this
cooling trend, lows Thursday morning may drop below 40 F, with the
best chance (20-40%) near the Dakota border and over Sheridan
County WY.

By Friday, upper level ridging is expected to build back over the
region, leading to warmer and drier conditions to end the week,
with highs again in the 80s for most locations by Saturday. Archer

&&

.AVIATION...

Early morning fog has become less probable at TAF sites, but low
stratus with IFR-LIFR ceilings will affect locations near the
Dakotas border (i.e. near KBHK & K77M) thru ~16z. Isolated morning
showers will increase to isolated (west) to scattered (east)
showers and weak thunderstorms this afternoon/evening. Local MVFR
is possible with the heavier showers, and mountains will be
obscured at times. The probability of a TS impacting a TAF site is
less than 20%. There is a risk (40% chance) of stratus/fog in
Fallon & Carter Counties again late tonight, with IFR-LIFR
possible. The remainder of the region will see clearing skies and
widespread VFR tonight. By early Sunday, lofted wildfire smoke may
reduce slant range visibility over the west. JKL

&&

.PRELIMINARY POINT TEMP/POPS...

    Tdy Sun     Mon     Tue     Wed     Thu     Fri
-------------------------------------------------------
BIL 079 055/088 057/088 057/087 055/078 053/084 053/084
    2/T 00/U    00/U    00/U    11/B    00/U    00/U
LVM 081 048/085 049/086 050/085 050/081 049/084 048/084
    1/U 00/U    00/U    01/U    01/U    00/U    01/U
HDN 079 052/088 054/088 053/087 052/079 049/083 048/085
    3/T 10/U    00/U    00/U    21/B    00/U    00/U
MLS 079 055/085 056/088 056/084 053/074 049/082 050/080
    3/T 10/U    00/U    01/U    20/B    00/U    00/U
4BQ 074 054/080 055/085 055/082 053/073 048/078 050/079
    3/T 20/U    00/U    01/U    21/B    00/U    00/U
BHK 074 052/080 052/085 052/079 047/070 043/077 045/078
    3/T 21/B    00/U    01/U    20/B    00/U    00/U
SHR 075 048/083 049/085 050/085 050/077 047/080 047/081
    5/T 10/U    00/U    01/U    22/T    00/U    00/U

&&

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

&&

$$
weather.gov/billings