184
FXUS65 KBYZ 182034
AFDBYZ

Area Forecast Discussion...Updated
National Weather Service Billings MT
234 PM MDT Tue Aug 18 2026

.KEY MESSAGES...

- Scattered showers and thunderstorms expected again today. A few
  storms could be strong to severe.

- Drier conditions Wednesday through Friday.

- Seasonal temps in the 80s through midweek, pushing into the
  lower 90s by late week. Increasing chance of precipitation over
  the weekend.

&&

.UPDATE...

A Severe Thunderstorm Watch has been issued for areas of
Musselshell, Yellowstone and Carbon counties eastward through 9 pm
MDT this evening. Wind gusts to 65 mph, half dollar (1.25") and
brief heavy rain are possible with stronger storms.

.DISCUSSION...

Today through Monday...

A shortwave under northwest flow is expected to bring scattered
showers and thunderstorms to the region this afternoon and
evening. Looking at moisture/dewpoints across the region compared
to models, it appears that there is more moisture than models are
showing. This would indicate that instability/CAPE values may be
slightly underdone. Models are currently showing MUCAPE values of
800-1200 J/kg and 30-40 kts of bulk shear. This, along with
precipitable water values near an inch, the main risks with any
strong to severe thunderstorm will be heavy rain, large hail and
strong winds. Short term ensembles are in good agreement that
thunderstorms will initiate of the Little Belt and Snowy mountains
and the Beartooth/Absaroka mountains early afternoon tracking
east/southeast, similar to previous days. One limiting factor to
thunderstorm initiation off the Beartooth/Absarokas will likely
be from the line of persistent showers along the foothills that`s
been present through the morning.

The transition into a more westerly flow aloft is expected to
bring smoke and hazy conditions to the region Wednesday. Subsidence
and ridging behind the shortwave will transition the region into
a warmer and dryer pattern for the end of the week. Looks towards
the weekend, ensembles are hinting at a shortwave moving through
the northern portion of the state, but there is still uncertainty
on the timing. If this scenario were to play out, there would be a
concern for breezy conditions creating fire weather concerns
given the already warm and dry conditions. This will be something
to watch through the week. In the meantime, be careful not to
cause a spark.

High temperatures will be in the 80s to low 90s through the
period. TS


.AVIATION...

Isolated to scattered showers and thunderstorms are forecast to
develop and move eastward through the area this afternoon and
evening. The main threats with the convection today are strong
wind gusts of 40 to 50+ knots, hail, and brief heavy rain
temporarily reducing visibility to MVFR or IFR. These showers and
thunderstorms are expected to come to an end across the area late
this evening into tonight.

Hazy skies will likely return to the area Wednesday as wildfire
smoke from distant wildfires moves over the region. Late
Wednesday, surface smoke concentrations may increase enough to
cause surface visibility reductions over portions of the plains
as well, though confidence is low on this at this time. LA

&&

.PRELIMINARY POINT TEMP/POPS...

    Tdy Wed     Thu     Fri     Sat     Sun     Mon
-------------------------------------------------------
BIL 087 059/088 059/093 063/091 065/090 064/089 062/087
    4/T 30/U    00/U    00/B    13/W    32/W    21/U
LVM 085 048/085 050/092 055/091 057/087 053/086 051/085
    3/T 20/U    00/U    00/B    24/T    42/T    21/U
HDN 090 054/090 054/094 059/093 063/092 061/091 059/090
    3/T 20/U    00/U    00/U    12/W    21/B    21/U
MLS 085 058/089 059/092 062/091 064/091 065/090 062/089
    3/T 30/K    00/U    00/U    02/W    31/B    10/U
4BQ 085 059/088 059/092 062/092 065/091 065/090 063/088
    2/T 60/U    00/U    00/U    02/T    32/T    21/U
BHK 083 054/088 056/091 057/089 057/088 059/090 058/089
    2/T 20/U    00/U    00/U    01/N    41/B    21/U
SHR 083 051/086 053/091 057/092 059/090 059/088 056/086
    6/T 30/U    00/U    00/U    02/T    22/T    21/U

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...Severe Thunderstorm Watch 596 in effect until 9 PM MDT this
      evening FOR ZONES
      29>33-36-37-56>58-67-138-139-169>171-173-235.
WY...Severe Thunderstorm Watch 596 in effect until 9 PM MDT this
      evening FOR ZONES 198-199.

&&

$$
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