A thunderstorm occurred over Carbon County, producing damages indicative of a microburst. No weather stations were able to record the wind speeds.
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Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS BYZ wrote it up.
A thunderstorm occurred over Carbon County, producing damages indicative of a microburst. No weather stations were able to record the wind speeds.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Billings, MT wrote its last area forecast discussion before the first event at Aug 12, 1:13 AM MST, 4 hours 32 minutes earlier. Its key messages:
Area Forecast Discussion
National Weather Service Billings MT
213 AM MDT Tue Aug 12 2025
.KEY MESSAGES...
- Warmer (90s) with isolated late day thunderstorms today. Any
storms could produce locally strong wind gusts.
- Hot Wednesday with a few triple digit readings possible.
Isolated late day thunderstorms with strong wind gusts possible.
- Elevated Fire Weather conditions Wednesday over the western
foothills (Harlowton, Livingston, Big Timber). Low Relative
Humidities and westerly winds gusting 20 to 30 mph.
- Slightly cooler and mainly dry for the end of the week.
&&
.DISCUSSION...
Through Wednesday night...
Typical Summer pattern over the next few days. Northerly flow
aloft this morning gets replaced by westerly flow this afternoon
through Wednesday. This transition will allow much warmer mid
level air to move into the area, boosting surface temperatures
with afternoon mixing. Expect highs in the lower 90s over central
and western portions of the forecast area this afternoon, with mid
80s holding on along the eastern state line for one more day.
Models have increased their convective potential for this
afternoon as a 50kt westerly jet streak arrives in the area late
afternoon into this evening. Convection is going to be working
against very warm mid level temperatures with 700mb temps
approaching +15C over the southwest mountains. The +12C line (the
normal delineation for significant convective potential) is
oriented from Ryegate to Billings to east of Sheridan by 6pm this
evening and continuing to spread eastward during the evening
hours. Given this less favorable environment for convection will
be keeping convection isolated in the forecast for now,
especially to the west of the above +12C line. Any thunderstorm
that do manage to hold together will be high based with strong
Inverted V soundings suggesting strong wind gust potential. HREF
is suggesting gusts 50+ mph are possible near storms.
Elevated convection may continue into SE Montana overnight tonight
as the upper level dynamics and any ongoing convection interacts
with the nocturnal Low Level Jet in this area. Again this
convection should be weak but something to be aware of overnight.
Wednesday will be warmer than today, and the warmest period of the
7 day forecast, with highs in the mid to upper 90s. A few
locations reaching the triple digits can't be ruled out. Mid level
temperatures are warmer tomorrow as well, though ensembles
continue to develop at least a few cells off the western mountains
and drift them eastward into the lower elevations. Once again
these will produce little precipitation but could put down some
strong wind gusts.
Wednesday will see enhanced fire weather conditions for the
western foothills, as mixed winds produce gusts 20 to 30 mph and
RH values drop into the teens. At this point fuels don't
necessitate Red Flag highlites on this side of the divide,
especially given the expected short duration of the hot/dry/breezy
conditions, with temperatures dropping 10 degrees and less gusty
winds forecast for Thursday. That said be very careful with any
activities that could spark a fire tomorrow. Chambers
Thursday through Monday...
A low pressure system moving through Canada will lower heights
and push a cold front through the region on Thursday. While this
frontal passage looks to be mostly dry, it will bring slightly
cooler, near-normal temperatures back to the region after a hot
day on Wednesday. Along with the slightly cooler temperatures,
breezy conditions look to occur with gusts in the teens and 20s
common across the area.
Friday into the weekend will see temperatures remaining near
normal as the flow aloft slowly backs to the southwest. At the
surface, winds looks to turn out of the east to south-east over
the plains, allowing some atmospheric moisture to move back into
the region. While there are daily, low chances of precipitation
for portions of the region with this flow regime (10 to 25
percent), the lack of any major wave / jet moving into our region
looks to keep things relatively benign through the period.
By the beginning of next week, cluster analysis suggests there is
good agreement on upper level ridging building into the region.
This would favor warmer and drier conditions across the region.
Arends
&&
.AVIATION...
Wildfire smoke will filter back into far eastern Montana this
morning. With this, slant range visibility will be reduced at
times. Otherwise, VFR conditions will prevail through today. This
afternoon and evening, isolated showers and weak thunderstorms are
possible along the Montana-Wyoming state line (10 to 20 percent
chance). With this, KSHR could see TS impacts this evening, but
confidence remains low at this time. Arends
&&
.PRELIMINARY POINT TEMP/POPS...
Tdy Wed Thu Fri Sat Sun Mon
-------------------------------------------------------
BIL 092 063/096 063/089 059/089 061/093 063/091 062/094
0/U 11/U 10/U 00/U 00/U 11/U 11/U
LVM 092 055/093 054/089 050/089 052/089 054/089 054/089
1/U 11/U 11/U 00/U 11/U 12/T 21/U
HDN 092 060/097 062/089 058/090 059/093 060/092 059/094
0/U 10/U 10/U 10/U 00/U 11/U 11/U
MLS 087 063/096 065/087 060/086 063/092 066/091 064/092
0/U 10/U 10/U 10/U 11/U 11/U 21/U
4BQ 087 063/093 065/089 061/089 064/091 065/090 064/091
0/U 10/U 10/U 10/U 11/U 21/U 21/U
BHK 082 058/093 060/087 057/085 059/086 061/087 059/086
0/U 10/U 10/U 11/U 11/U 22/T 21/U
SHR 089 058/092 059/090 056/088 058/091 058/088 057/090
1/U 21/U 10/U 11/U 11/U 12/T 11/U
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...None.
WY...None.
&&
weather.gov/billingsThe Billings radar (KBLX), 66 km away, was scanning. The volume nearest the first event began at 12:46 UTC.
1 thunderstorm wind. Local standard time, as filed.
Tree damage, 2 large trees uprooted, grain silo destroyed. Very localized damage suggestive of a microburst. Gust estimated via damage information provided.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Montana in 2025Every state in 2025This day in weather historyWarnings in Montana, August 2025
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 1293318.