953
FXUS65 KBYZ 280026
AFDBYZ

Area Forecast Discussion...Updated
National Weather Service Billings MT
626 PM MDT Sun Sep 27 2026

.KEY MESSAGES...

- Isolated showers and a few strong thunderstorms are possible
  this evening and overnight. Best chance for precipitation will
  be over the Beartooth/Absaroka mountains and SE Montana.

- Mild and dry pattern prevails Tuesday into next weekend.

&&

.UPDATE...

Quick update for latest precipitation potential and trends through
the day on Monday. A conditional threat for a strong thunderstorm
or two remains in place over the areas from Rosebud county east
into the Dakotas from around 9pm through sunrise tomorrow morning
based on elevated CAPE/Shear values. Storms will have to contend
with a significant overnight cap though, so this threat is low
(10% chance). Otherwise isolated to scattered showers and a few
embedded thunderstorms can be expected across the area over the
next 24 hours, with generally light precipitation accumulations
expected. Best area for precipitation will be over SE Montana.
Chambers

&&

.DISCUSSION...

Today through Saturday...

Current upper level pattern shows southwest flow with troughing
over the west coast. Multiple rounds of energy will work their way
through the region as troughing moves south and east.
Precipitation amounts continue the downward trend for this evening
and overnight. Areas along the MT/Dakotas border have about a
20-40% chance for at least a quarter inch of precipitation, with
the Beartooth/Absarokas having similar chances for a half an
inch Sunday night into Monday. With precipitable water values
continuing to be elevated across SE MT, locally higher rainfall
amounts are possible with any stronger thunderstorms that form.
One limiting factor for thunderstorm development continues to be a
cap/inversion in model soundings for this area. Hi-res ensembles
and models continue to show MUCAPE values of 500-1000 J/kg and
35-45 kts of bulk shear. If storms are able to tap into the energy
available, heavy rain, small hail and gusty winds are likely. The
best timeframe for storms this evening and overnight looks to be
9pm-6am MDT Monday morning. There is then about a 20% chance for
low stratus/fog to develop Monday morning for SE MT as well.
Additional scattered showers and isolated thunderstorms are
possible into Monday afternoon mainly across the higher terrain
and southeast MT. Low clouds may limit thunderstorm development as
dryer air and clearing does not move in until the evening. Timing
for potential thunderstorms Monday looks to be mainly during the
afternoon hours. Dryer air moves in Tuesday as west to northwest
flow moves in and persists through the week. High temperatures
will remain seasonable in the 60s to low 70s, with Tuesday
trending warmer in the upper 70s. TS

.AVIATION...

00z TAF/Aviation Discussion...Upper level system over the area
tonight through tomorrow will produce isolated to scattered
showers and a few embedded thunderstorms. There is a conditional
threat for a few strong thunderstorms late this evening into
tomorrow morning from Rosebud county east into the Dakotas and NE
Wyoming. Stratus and localized fog are a possibility over SE
Montana after about 09z lasting into the late morning hours
Monday, with MVFR to IFR flight categories possible including
KMLS/KBHK/K4BQ. Winds will become light overnight at the surface,
but near showers/thundestorms gusts 20 to 30kts are possible.
Chambers

&&

.PRELIMINARY POINT TEMP/POPS...

    Mon     Tue     Wed     Thu     Fri     Sat     Sun
-----------------------------------------------------------
BIL 045/070 046/077 051/071 044/067 045/073 049/067 045/068
    31/B    10/U    00/U    00/U    00/U    11/B    10/U
LVM 041/070 039/075 044/071 038/070 041/075 044/069 039/071
    12/T    10/U    00/U    00/U    00/U    11/U    10/U
HDN 044/070 043/078 047/071 042/069 042/074 046/068 042/069
    21/B    00/U    00/U    00/U    00/U    11/B    10/U
MLS 051/070 046/077 050/069 043/065 045/071 048/067 044/066
    21/E    10/U    00/U    01/U    00/U    11/B    10/U
4BQ 052/070 048/077 050/070 045/066 046/073 049/068 045/066
    32/W    20/U    00/U    01/U    00/U    10/B    10/U
BHK 052/071 046/077 048/070 040/064 041/071 044/067 040/064
    52/T    20/U    00/U    01/U    00/U    01/B    10/U
SHR 048/068 042/075 043/070 040/067 040/073 045/068 040/068
    33/W    10/U    00/U    11/U    00/U    11/B    10/U

&&

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

&&

$$
weather.gov/billings