Strong winds aloft that mixed to the surface, combined with a tight west/east surface pressure gradient, resulted in high wind gusts across the western portions of the Billings Forecast Area.
Every event with a place to put it; 11 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
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.
Strong winds aloft that mixed to the surface, combined with a tight west/east surface pressure gradient, resulted in high wind gusts across the western portions of the Billings Forecast Area.
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 Feb 21, 2:43 AM MST, 3 hours 12 minutes earlier.
Area Forecast Discussion
National Weather Service Billings MT
243 AM MST Sun Feb 21 2021
.DISCUSSION...
Today and tonight...
Surface pressure gradient was tightening up over the western
foothills. Winds were responding at Big Timber with gusts to 40
mph already. Strong mid level winds move into the area this
afternoon and this is when the stronger winds will get cranking.
700 mb winds up to 70 kts slide in and this should be enough (in
combination with tight surface pressure gradient) to allow for
Warning level winds to be hit from Livingston to Big Timber to
Harlowton. These strong mid level winds move across the northern
zones tonight and Monday. Atmosphere looks potentially unstable
enough for some the ridges and peaks of the northern zones to hit
Warning criteria too, starting as early as late tonight. Have
decided to issue a High Wind Warning for the northern tier of
zones from Golden Valley to Rosebud for tonight and Monday. Also
issued a High Wind Watch for Custer and Fallon counties for Monday
as inversions looks to give way there and allow strong winds off
the surface to potentially mix down. The question will be ascent,
as models were advertising some. This could keep the strongest
winds elevated. That being said, believe at least the peaks and
ridge should get Warning level winds.
For Billings, today will be windy again, with some gusts to 35
mph by afternoon. 50 kt winds at 850 mb slide over south central
Montana tonight and Monday, but soundings show a strong inversion,
which would prevent the strongest winds from surfacing at
Billings. Will have to watch this closely though, as losing snow
cover may allow the inversion to be broken, and if this
materializes, may be able to tap into the stronger winds aloft.
Precipitation chances will be confined to the mountains today and
tonight. Northwest flow and adequate instability should provide
periodic snow showers for the higher terrain and a chance just off
the mountains over the foothills. Temperatures will be warmer
today as readings approach normal. Snow cover will provide a
limiting factor to the warmup for locations with lingering think
depths. TWH
Monday through Sunday...
Overall, the story remains the same for the extended forecast
period. Strong and gusty winds Monday is the biggest concern for
the period, followed by a cold front Tuesday. Mainly dry, with the
exception of mountain snow, and cooler to end the period. That
said, there have been a few changes through the period.
Winds have been increased across the northern tier of the CWA for
Monday, to reflect improved potential for strong 700mb winds to
mix out. Northern zones had less snow cover from the previous
snow event, which has been further eroded over the past few days.
Additionally, areas of higher terrain, including Bull Mountains,
Hysham Hills, will have great potential for seeing high winds. A
High Wind Warning has been expanded to include counties across
the northern tier of the CWA through Northern Rosebud County. A
High Wind Watch has been issued for Custer and Fallon Counties at
this time. We continue to watch remainder of CWA for indications
that highs winds will impact a broader area than expected.
As for the cold front on Tuesday, the system appears on track to
bring cooler temps and some precip across the region. There is
some potential for a period of strong winds accompanying FROPA.
Strong winds persist just above the surface, which should mix
down as the front breaks down the inversion over the area. Have
introduced some stronger winds, associated with rough estimate of
frontal passage on Tuesday. Strongest winds may not last too
long, but thought worth mention of increased winds with the front.
Dry conditions should return for Thursday, and gusty winds will
also return for areas from Harlowton to Big Timber to Livingston.
Shortwave ridging takes over aloft, and lee side surface troughing
quickly develops. A tight surface gradient quickly sets up to
bring strong gap flow to Livingston to start the day. The surface
gradient shifts to more of a west to east gradient later in the
day, supporting a period of strong gusty winds from Big Timber to
Harlowton Thursday afternoon/evening. Have increased the
advertised winds for this period as well, but have kept sub
advisory level at this time.
Another disturbance is progged to push into the region Friday
night through Saturday. This will bring some reinforcing cool air
to the region and a chance for snow, but limited accumulations
outside area mountains.
Temperatures will be in the 40s and 50s Monday, before falling into
the 30s and 40s for Tuesday. Highs are expected to be mainly in
the 30s through the remainder of the forecast period, though highs
may not make it past the 20s Saturday. Gilstad
&&
.AVIATION...
Winds will increase over the western foothills this morning and
continue to increase through the day today. Gusts of 50kts are
expected at KLVM this morning, with 60kts late today and 65-70kts
tonight and Monday. Expect LLWS at KMLS this morning. The
mountains will see a steady stream of snow showers and this will
cause the mountains to be obscured. TWH
&&
.PRELIMINARY POINT TEMP/POPS...
Tdy Mon Tue Wed Thu Fri Sat
-------------------------------------------------------
BIL 039 030/050 031/039 020/034 016/035 022/035 017/027
0/N 10/N 44/O 21/B 00/B 11/B 22/S
LVM 039 031/049 028/035 015/029 013/034 020/032 017/028
1/N 11/N 46/S 21/B 02/S 23/S 33/S
HDN 040 026/050 029/040 018/035 012/039 020/038 015/029
0/N 00/N 34/O 21/B 00/B 11/B 23/S
MLS 040 030/052 030/040 020/035 016/040 023/039 014/029
0/N 00/N 53/O 21/B 00/B 10/B 11/E
4BQ 039 028/052 031/040 021/034 016/038 022/037 017/029
0/N 00/N 33/O 21/B 00/U 10/B 12/S
BHK 039 027/052 028/039 017/034 014/040 020/038 012/026
0/N 00/N 43/O 10/B 00/U 00/B 11/B
SHR 039 021/051 026/038 014/030 006/037 017/034 012/027
0/B 10/N 15/S 32/S 00/B 11/B 23/S
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...High Wind Warning in effect from 10 PM this evening to 6 PM
MST Monday FOR ZONES 29>31-42-173.
High Wind Watch in effect from Monday morning through Monday
afternoon FOR ZONES 32-33.
High Wind Warning in effect until 5 AM MST Tuesday FOR ZONES
63-65-66-141-172-228.
WY...None.
&&
weather.gov/billingsPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BILLINGS MT
551 AM MST SUN FEB 21 2021
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0540 AM NON-TSTM WND GST 2 SSW BIG TIMBER 45.81N 109.98W
02/21/2021 M55.00 MPH SWEET GRASS MT AWOS
&&
TWHThe national radar mosaic for the moment the first event began.
11 high wind. Local standard time, as filed.
Winds gusted to 59 mph across the Big Timber area.
Winds gusted to 58 mph across the area.
Winds gusted to 58 mph across the area.
Winds gusted to 58 mph across the area.
A gust of 82 mph was recorded at the Livingston airport.
Winds gusted to 58 mph across the area.
Winds gusted 58 to 62 mph across the area.
Winds gusted to 67 mph across the Roundup area.
Winds gusted to 58 mph across the area.
Winds gusted to 58 mph across the area.
Winds gusted to 63 mph across the Forsyth 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, February 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: 937728, 937730, 942198, 942199, 937734, 942194, 942193, 942197, 942195, 937731, 942196.