193
FXUS65 KBYZ 062039
AFDBYZ

Area Forecast Discussion
National Weather Service Billings MT
239 PM MDT Sun Sep 6 2026

.KEY MESSAGES...

- A weather system will bring periods of isolated to scattered
  showers and thunderstorms to region today into Monday.

- Thunderstorms today and Monday will be capable of producing
  localized heavy rain, gusty winds, and hail. The risk of strong
  to severe thunderstorms is greatest today into tonight.

- 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.

- After a mostly dry mid-week, a weather system looks to bring
  cooler temperatures and the chance of precipitation back to the
  area Friday into the weekend. However, uncertainty remains.

&&

.DISCUSSION...

Today through Saturday...

Mainly dry conditions under mostly sunny to partly cloudy skies
exist early this afternoon. While there is instability aloft (CAPE
values around 1000 to 3000 J/kg), a low level cap is inhibiting
convection at the moment, and modeled atmospheric soundings
suggest this cap will persist through much of the day for most
areas. However, over far eastern Montana (mainly Fallon and Carter
Counties), surface temperatures warming into the low to mid 90s
may be enough for isolated thunderstorm development late this
afternoon into this evening. With good instability and shear, any
thunderstorm that develops in this region today may quickly become
strong to severe, with gusty winds, heavy rain, and hail being
the main threats. Currently, the Storm Prediction Center (SPC) is
advertising a Marginal Risk (Level 1 out of 5) for severe
thunderstorms in this area. The other area to watch during the day
today is the mountains, which may provide enough orographic lift
for convention to overcome the cap. Should this occur, high- based
thunderstorms moving over the plains of south- central Montana
cannot be ruled out. However, the chance remains low at this point
(around a 15 percent chance). As you move west over western
Montana, the chance does increase, and this is where the SPC has a
Slight Risk (Level 2 out of 5) for severe thunderstorms later
today.

This evening into tonight, a shortwave trough ahead of an
approaching low pressure system is expected to pass through the
region. As this occurs, this shortwave is expected to provide
enough lift to overcome the deepening low level inversion and
subsequent cap, allowing scattered showers and thunderstorms to
develop and move north to northeastward through much of the area.
With this, the chance of precipitation is greatest over south-
central Montana (where there is up to a 70 percent chance of
precipitation), but recent model runs suggest the chance of
precipitation has also increased over south-eastern Montana and
north-eastern Wyoming (Sheridan County) where there is now a 25 to
40 percent chance of precipitation. As previously mentioned,
there is instability aloft today, and this is expected to stick
around into tonight. Therefore, a few strong to severe
thunderstorms are possible late this evening into tonight, mainly
over south- central Montana. With this, the main threats are heavy
rain, gusty winds, and hail. Currently, the SPC has a Marginal
Risk (Level 1 out of 5) of severe thunderstorms for this area as
well. By early Monday morning, expect the scattered showers and
thunderstorms to decrease in coverage across the area. The risk of
severe thunderstorms will be much lower by this time.

The break in precipitation is not expected to last long before
another round of isolated showers and thunderstorms develop later
Monday morning into Monday afternoon over south- central Montana.
While this convection will be supported by the approaching low
pressure system, developing westerly winds will work to dry out
the lower atmosphere, potentially limiting convection. Any showers
or thunderstorms that do develop will gradually move eastward
into eastern Montana by Monday evening. With this, cannot rule out
localized strong winds under thunderstorms, but the risk of
severe thunderstorms remains low overall. The main hazard on
Monday instead 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 to develop Monday afternoon, with the
strongest gusts existing 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 afternoon into Monday evening
(60 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, with a few 50 mph wind gusts possible around Baker,
Montana (40 percent chance).

Wednesday into Thursday look to be mostly dry days as
temperatures warm back above normal behind the early week weather
system. Friday into the weekend, there are signs that another
weather system will bring precipitation and much cooler
temperatures to the area, however, uncertainty remains. LA

.AVIATION...

Multiple rounds of scattered showers and thunderstorms are
expected this evening into Monday. The main concern with these
thunderstorms will be heavy rain, gusty winds 40-50kts and
localized large hail up to an inch. There is a moderate chance
for areas of low stratus to form again Monday morning for KMLS
with less confidence for KBIL and KLVM. MVFR conditions will be
likely with any heavy rain/low stratus. TS

&&

.PRELIMINARY POINT TEMP/POPS...

    Mon     Tue     Wed     Thu     Fri     Sat     Sun
-----------------------------------------------------------
BIL 061/080 052/075 050/081 054/087 055/074 048/065 045/067
    52/T    00/U    00/U    00/U    01/B    33/W    33/W
LVM 051/071 041/071 040/079 046/084 048/075 041/065 038/067
    44/T    00/N    00/U    00/N    12/T    44/T    43/W
HDN 058/085 046/078 045/082 045/089 049/077 045/068 041/069
    32/T    10/U    00/U    00/U    01/B    33/W    32/W
MLS 065/084 053/076 049/079 050/086 053/074 046/067 043/068
    43/T    20/N    10/U    00/U    11/B    43/W    32/W
4BQ 069/087 052/079 050/080 051/088 055/078 048/069 045/069
    42/T    20/U    00/U    00/U    00/U    33/W    32/W
BHK 063/087 050/078 044/079 047/087 049/077 042/068 039/068
    43/W    20/N    10/U    00/U    01/U    43/W    32/W
SHR 057/083 044/077 043/078 045/086 050/079 043/067 039/068
    22/T    00/U    00/U    00/U    01/U    34/W    42/W

&&

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

&&

$$
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