High Wind gusts occurred along the Beartooth Foothills during the early evening on the 28th.
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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.
High Wind gusts occurred along the Beartooth Foothills during the early evening on the 28th.
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 Sep 28, 1:39 PM MST, 5 hours 6 minutes earlier.
Area Forecast Discussion...CORRECTED
National Weather Service Billings MT
239 PM MDT Tue Sep 28 2021
.DISCUSSION...
Rest of Today through Wednesday Night...
Persistent flow of gravity waves off the northern edge of the
Pryor Mountains have kept Billings temperatures at a mild 70
degrees as of 1 PM, and show no sign of stopping until the front
reaches the area. To the west, sharp pressure rises are observed
behind the cold front. We are starting to see northwest winds in
central Montana with gusts up to 32 mph, and these wind speeds
will increase as an 850 jet maxima begins to form over the next
few hours, and spread into eastern Montana. In southeast Montana,
deepening of the surface low over south-central Montana has
sharpened the pressure gradient out there and brought about gusts
to 35 mph in Carter County.
Frontal timing is delayed by 1-2 hours, but otherwise stays on
track. The strongest winds look to not occur until the evening
when those 850 winds are expected to max out, so expect initial
gusts to 35 mph immediately behind the front, with an increase to
gusts up to 45 mph this evening. Winds will remain strong
overnight and slowly decrease throughout Wednesday.
Some water vapor exists on satellite imagery over south- central
MT, and as the front pushes it west, will provide a chance for
light rain showers across the area. Slightly better odds for rain
showers tomorrow morning and afternoon as an upper low over
Colorado slowly pushes more moisture into the area, but
regardless, rain amounts will still be minimal. Expect rain to
switch to snow in the mountains and much higher elevations this
evening.
Vertz
Thursday Morning through Tuesday...
A dry airmass returns Thursday as the upper-level trough exits to
the east. Temperatures will remain in the lower 70s for most of
the area and the 60s for higher elevations. A weak wave will clip
the area to the north on Saturday which will bring another small
drop in temperatures - into the upper 60s - and a very marginal
chance for rain north of Billings. Overall moisture in the
atmosphere remains low, so any rain amounts will be very light. By
Sunday, temperatures will be back into the mid-70s, and winds
will be relatively light. What looks like a pleasantly cool, calm,
fall pattern will take us into the first week of spooky season.
Behringer
&&
.AVIATION...
Cold front currently making it's way across all terminals from
northwest to southeast. Expect initial gusts of 35 mph behind the
front to increase to 45 mph by this evening, then a gradual
decrease in winds throughout Wednesday. Some light rain shower
activity possible, and expect mountains to be obscured. Vertz
&&
.PRELIMINARY POINT TEMP/POPS...
Wed Thu Fri Sat Sun Mon Tue
-----------------------------------------------------------
BIL 044/063 038/069 042/073 044/070 043/073 044/074 044/073
20/B 00/U 00/U 11/U 10/U 00/U 00/U
LVM 033/062 031/070 037/073 038/070 038/073 039/075 040/074
20/U 00/H 00/U 11/U 00/U 00/U 00/U
HDN 045/063 035/070 037/074 041/071 041/073 041/075 040/075
21/E 00/U 00/U 11/U 11/U 00/U 00/U
MLS 050/064 040/069 041/074 045/072 044/072 044/073 044/072
32/W 00/U 00/U 11/B 11/U 00/U 00/U
4BQ 048/061 043/067 042/073 045/071 044/071 045/071 044/071
44/W 00/U 00/U 11/U 11/B 00/U 00/U
BHK 048/063 041/069 042/073 045/072 044/071 044/070 042/068
35/W 20/U 00/U 11/U 11/U 11/U 11/U
SHR 043/059 035/067 037/073 040/070 040/072 039/073 040/073
33/W 10/U 00/U 11/U 11/U 10/U 01/U
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...Red Flag Warning in effect until 9 PM MDT this evening FOR
ZONES 125>133.
WY...Red Flag Warning in effect until 9 PM MDT this evening FOR
ZONES 274-284.
&&
weather.gov/billingsThe national radar mosaic for the moment the first event began.
1 high wind. Local standard time, as filed.
Winds gusted to 75 mph across the area.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Montana in 2021Every state in 2021This day in weather historyWarnings in Montana, September 2021
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: 984975.