Severe Thunderstorm Warning 21, NWS Billings, MT

Area Forecast Discussion
National Weather Service Billings MT
1257 PM MDT Fri Jun 13 2025

.KEY MESSAGES...

- Enhanced risk (3/5) of severe thunderstorms today. Main threats
  are strong winds, large hail, and heavy rain. A small chance for
  tornadoes.

- There is daily potential for thunderstorms through the coming
  weekend; some severe thunderstorms are possible. Monitor the
  forecast.

- High elevation snowmelt will allow flows on rivers and streams
  to increase into the second half of this week. No flooding is
  expected at this time.

&&

.DISCUSSION...

Through Saturday night...

Patchy fog will be possible across much of southeast Montana
Saturday morning as a moist airmass remains in the area.
Locations near the Dakotas border will have the best chance at
seeing fog development. Prepare for localized reductions in
visibility on roadways.

A similar setup to today will bring the potential for strong
thunderstorms Saturday. A moist airmass will stay in place with
dewpoint values in the mid 50s to low 60s F. This will act to
increase convective potential with CAPE values nearing 2,000 J/kg
across much of the region. The upper level jet will lift to the
north slightly, reducing 0-6 km bulk shear into the 40-50 kt
range. This is still adequate to sustain severe storms. Hodographs
will be 'shorter' than today indicating weaker upper level winds.
The main threat for Saturday will be hail greater than 1 inch and
winds in excess of 60 mph. The moist airmass will also act to
decrease dewpoint depressions and LCLs increasing tornado
potential (2%). The Storm Prediction Center has issued a level 2
of 5 threat for severe thunderstorms for locations east of
Billings and a level 1 threat for locations elsewhere. Timing of
these storms will generally be between 3 pm and 11 pm. Torgerson

Sunday through Thursday...

The active pattern with near daily chances of afternoon
thunderstorms will persist through mid next week. Repeated
shortwave troughs / vorticity maximums will move through the
region providing a lifting mechanism for these storms.
Additionally, good WAA and moisture advection will continue with
an easterly surface wind across the CWA and veering winds with
height through the mid-levels.

On Sunday, shear values are forecast to be similar to
Friday & Saturday. SB CAPE values are actually forecast to be a
little higher with widespread values between 2000-3000 J/kg. A
decently strong shortwave trough will move up through ID into
western MT that will provide broad scale ascent and should be the
catalyst for these stronger storms. A lot of Sunday's setup looks
similar to that of Today's setup so future model runs and outlooks
will need to be monitored closely. A couple of storms could pack
quite a punch with all severe hazards possible.

Little change is likely heading into next week as all models are
in good agreement that no big disturbance in the jet stream is
forecast. Zonal flow with repeated shower chances appear likely to
stick around. Also expect slightly above average temperatures and
high humidity through mid-next week.

WMR

&&

.AVIATION...

Showers and thunderstorms will decrease overnight. See below for
thunderstorm timing. Fog and low cloud will affect much of
southeast Montana Saturday morning. This will lead to a 20-50%
chance of seeing MVFR conditions with the highest risk being near
the Dakotas border. Showers and thunderstorms will affect the
region again Saturday with thunderstorms starting around 21Z.
These thunderstorms will bring the potential for strong winds in
excess of 50 kts and large hail. Archer/Torgerson

Location |  Timing
---------------------
KLVM      Through 04z
KBIL      Through 05Z
KSHR      Through 05Z
KMLS      Through 05Z

&&

.PRELIMINARY POINT TEMP/POPS...

    Sat     Sun     Mon     Tue     Wed     Thu     Fri
-----------------------------------------------------------
BIL 058/083 059/082 058/077 056/074 054/081 056/086 057/084
    42/T    33/T    65/T    66/T    21/U    11/U    11/U
LVM 051/083 051/080 052/077 049/072 046/079 048/084 050/081
    23/T    34/T    46/T    65/T    21/U    11/U    21/U
HDN 058/085 058/084 057/079 055/073 052/080 054/087 056/086
    62/T    43/T    74/T    77/T    31/U    10/U    11/U
MLS 058/085 060/086 060/080 057/074 053/078 056/086 058/083
    51/U    54/T    83/T    66/T    41/U    10/U    21/U
4BQ 059/084 060/087 060/079 057/073 054/076 055/085 059/084
    52/T    43/T    72/T    77/T    41/U    10/U    11/U
BHK 054/081 056/082 056/077 054/073 051/075 051/083 056/082
    61/B    44/T    83/T    56/T    42/T    11/U    21/U
SHR 054/085 054/084 054/078 052/071 049/077 051/085 054/084
    34/T    34/T    44/T    78/T    31/U    01/U    11/U

&&

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

&&

weather.gov/billings