415
FXUS65 KBYZ 300226
AFDBYZ

Area Forecast Discussion...Updated
National Weather Service Billings MT
826 PM MDT Fri Aug 29 2025

.KEY MESSAGES...

- Scattered showers and thunderstorms continue across the region
  through Saturday, with locally heavy rainfall possible. Greatest
  potential for heavy rain will be east of the western foothills.

- There is a low risk of flash flooding in and near area burn
  scars today.

- Warmer and dry Sunday and Monday.

- Trending cooler and mainly dry Tuesday into Thursday.

&&

.UPDATE...

Minor update to the forecast to capture latest model
precipitation trends. Continue to see scattered showers and
isolated thunderstorms in the area. This activity, and the
associated monsoonal moisture, is trapped in a weakness in the
upper level flow and is just meandering around the area. So, will
keep at least low precipitation chances going overnight into
tomorrow for most locations. Radar showing a decrease in intensity
of convection as the sun sets. This should bring an end to
locally heavy rainfall under the stronger cells from earlier this
evening. Expect some fog development overnight with the light
winds and residual low level moisture in the area. Rest of the
forecast is in good shape. Chambers

&&

.DISCUSSION...

Through Saturday Night...

A low situated in Northern MT / Southern AB is forecast to linger
before slowly moving northwards into the prairie provinces. The
associated weak moisture return coming in off of the plains and
downslope flow from the higher elevation has set up a convergent
boundary across Eastern Montana. This boundary is forecast to
linger oriented KBIL/KSHR for the rest of the day today with the
potential for some lightning this afternoon and evening. There are
also convective cells popping along and east of this boundary
which could help to increase the coverage in storms this
afternoon. With the mean wind at roughly 20kts across the CWA,
PWATS around 1", and training storms, the potential for localized
flooding will need to be monitored for the rest of the day today.

As the low slowly drifts out of the area chances for precip will
slowly decrease from west to east during the day Saturday.
Tomorrow morning could also come with the potential for fog
across the region as well. With the recent precip over the past
several days there is ample surface moisture as as the low exits,
winds will become very light. Areas west of the CWA saw dense fog
for several hours this morning under similar conditions. The main
limiting factor seems to be that there is still a potential that
some precip could be falling during the morning hours.
Additionally, while winds are forecast to be under 5mph, the wind
direction does appear to be downslope which could limit fog
development. All this to say that there could be fog tomorrow
morning, however, the chance is highly conditional.

Some mid-range models show a weak vort max zip through the area
Saturday night into early Sunday which could being widely isolated
showers early Sunday. WMR

Sunday through Friday...

Sunday and Monday will feature increasing temperatures and drier
conditions as ridging moves in from the west keeping us in
northwest flow. Temperatures are expected to be in the 80s F both
days. The rest of the long term forecast will be dominated by a
large 500 mb trough that will descend from Canada and settle in
over the Great Lakes. This is expected to drop a cold front
through the northern plains next Tuesday. The highest confidence
in a cool down is for locations near the Dakotas border such as
Baker where the NBM is giving a reasonable temperature range of
59-70 F for Wednesday, while the same for Livingston is 69-83 F.
Looking at WPC clusters, there is high confidence in the overall
pattern, but significant uncertainty in how far west the impacts
will reach. The coldest morning looks to be Thursday morning with
locations near the Dakotas border and Sheridan County Wyoming
having a 20-40% chance of getting below 40 F with 0-20% chances
elsewhere. There is good agreement that by Friday the upper level
trough will begin to move to the east bringing increasing heights
and temperatures to Montana. Overall, a dry next 7 days is
expected. Torgerson

&&

.AVIATION...

Isolated showers and thunderstorms will continue through Saturday,
increasing to scattered for Saturday afternoon and evening. There
is a low chance (20%) of fog near all TAF sites through 14Z, which
may occasionally cause localized visibility reductions to IFR.
Expect mountain obscuration at times. Archer

&&

.PRELIMINARY POINT TEMP/POPS...

    Sat     Sun     Mon     Tue     Wed     Thu     Fri
-----------------------------------------------------------
BIL 057/081 057/088 057/087 057/086 054/079 052/082 053/085
    42/T    00/U    00/U    01/U    21/U    00/U    00/U
LVM 048/081 049/085 049/086 050/085 049/081 048/083 048/084
    31/U    00/U    00/U    01/U    11/U    01/U    11/B
HDN 056/080 051/088 053/087 053/086 051/078 048/082 048/084
    43/T    10/U    00/U    01/U    20/U    00/U    00/U
MLS 059/077 055/086 057/087 055/083 051/073 047/079 050/081
    33/T    20/U    00/U    01/B    20/U    00/U    00/U
4BQ 057/074 054/082 056/084 055/082 052/072 048/077 050/079
    33/T    20/U    00/U    01/U    30/B    00/U    00/U
BHK 054/073 051/082 052/085 052/078 045/068 041/074 044/077
    23/T    21/U    10/U    01/B    20/B    00/U    00/U
SHR 050/077 049/083 051/084 050/083 049/076 046/079 047/081
    24/T    11/U    00/U    01/U    31/B    11/U    00/U

&&

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

&&

$$
weather.gov/billings