A tight west/east surface pressure gradient resulted in some high wind gusts across northern Sweet Grass County.
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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 tight west/east surface pressure gradient resulted in some high wind gusts across northern Sweet Grass County.
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 Dec 8, 2:14 AM MST, 31 minutes earlier.
Area Forecast Discussion
National Weather Service Billings MT
214 AM MST Wed Dec 8 2021
.DISCUSSION...
Today through Thursday...
Upper level ridging is bringing us a brief period of dry/warmer
weather, but there is an upstream trof along the BC/WA coast that
is approaching and will bring us some precip tonight. Surface
analysis shows a deepening lee side trof with most rapid pressure
falls in north central MT and southern Alberta. The IDA-LWT
pressure difference is up to over 15mb. These pressure trends and
backing mid level winds are favoring the gap areas over the next
several hours, but as of 08z we are still seeing higher gusts at
Big Timber than Livingston airport (but they are decreasing at
6S0). Wicked Creek Raws is gusting into the 40s now, so fully
expect stronger gap flow (i.e. 60 mph gusts) to be developing very
soon. In fact, quick glance at the DOT stations show 55 mph gusts
at the western Livingston station. After a lull thru the
remainder of the night into early tomorrow, Big Timber and
Harlowton should see increasing winds with increased mixing thru
the day. Gusts of 50+ mph are expected in these areas. Will make
no changes to the wind highlights at this time. Frontal passage
will end the gap flow by evening.
Snow cover permitting, we should see widespread temps in the 40s
to near 50F today, per the downslope warming. Temps near 50F will
certainly happen near the foothills where current temps at many
locations are in the low 40s.
Pacific cold front will bring a quick chance of rain/snow showers
tonight, with accumulating snow for the mountains. Downslope winds
will remain dominant and precip will be mostly light. That being
said, NW wind upslope areas to the southeast of Billings could see
up to a tenth of an inch of precip and perhaps up to an inch of
wet snow. This seems most likely at places like the Wolf
Mountains, Aberdeen Hill, Lame Deer Divide and the eastern slopes
of the Bighorns including Sheridan and Story. With post-frontal
temps falling back to the 20s this will result in icy roads in
these areas for any late night travelers. Regarding Billings, only
a glancing shot of light rain/snow showers as breezy NW winds
persist behind the front.
Thursday will be dry and cooler (high temps in low-mid 30s) w/
breezy W-NW winds. Look for a few snow showers over the mountains.
JKL
Thursday Night through Wednesday...
Mainly dry conditions will prevail through the extended forecast
period. Cool temps will persist for Friday, under the influence of
an upper level trough, with highs expected to be around freezing.
Upper level ridging will take over Friday night and traverse the
area through Sunday. Winds aloft also increase Friday night, and
lee troughing develops along our western foothills, so expect to
see gusts of 50 to 60 mph, at least periodically, through the
weekend. Downslope flow will help enhance warming a trend through
the weekend, bringing temps in the mid to upper 40s by Sunday.
These temps may trend upward a bit more quickly, as combination
of wind and snow cover become more clear.
Upper flow becomes southwesterly by Sunday night, as
a Pacific trough deepening along the west coast. This should
cause lee trough to slacken, pointing to winds letting up across
the west late Sunday. Persistent southwesterly flow will bring
Pacific moisture into the mountains, resulting in mountain snow
showers and increase cloud cover across the west through the
remainder of the period. Expect to see temps take a slight dip,
without support of the winds, but still expect highs in the 40s
through the remainder of the forecast period.
The Pacific trough is progged to shift eastward late Tuesday,
bringing potential for precip into the lower elevations some time
Tuesday night or Wednesday. This system has plenty of moisture
embedded with it, so could be a significant precip producer. That
said, this potential would be for the middle to end of next week,
and a lot can change in that time. We will continue to watch
closely.
Gilstad
&&
.AVIATION...
Strong SW-W winds will continue along the western foothills today
(KLVM/K6S0/KHWQ), with gusts of 35-50 knots. These winds will
decrease tonight with the arrival of a cold front.
VFR will prevail across the region today. Local MVFR in scattered
rain/snow showers is expected tonight with the aforementioned
frontal passage. Mountains will be obscured in snow showers for a
good portion of the night. W-NW winds will gust 20-30 knots across
the region behind the cold front.
JKL
&&
.PRELIMINARY POINT TEMP/POPS...
Tdy Thu Fri Sat Sun Mon Tue
-------------------------------------------------------
BIL 043 022/033 014/031 017/036 028/043 024/042 027/043
1/B 40/U 10/U 00/B 00/B 11/B 11/B
LVM 048 020/033 014/032 021/039 030/046 032/047 033/048
2/N 50/N 10/N 00/N 12/W 12/W 23/W
HDN 044 022/035 013/032 013/038 023/047 020/042 022/045
1/E 50/B 10/B 00/B 00/B 00/B 01/B
MLS 044 022/035 014/032 017/039 025/045 022/040 022/043
1/B 30/U 00/U 00/B 00/B 00/B 00/B
4BQ 047 023/035 019/033 018/040 026/047 026/048 029/051
1/B 50/B 10/B 00/B 00/B 00/B 00/B
BHK 045 022/033 014/031 015/038 026/046 023/044 024/046
0/B 30/N 00/B 00/U 00/B 00/B 00/B
SHR 046 026/032 014/032 012/041 024/049 026/048 029/051
0/B 61/E 31/B 00/B 00/B 00/B 01/B
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...Wind Advisory in effect until 2 PM MST this afternoon FOR
ZONES 65-66.
High Wind Warning in effect until 6 PM MST this evening FOR
ZONE 141.
WY...None.
&&
weather.gov/billingsPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BILLINGS MT
929 PM MST TUE DEC 07 2021
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0835 PM NON-TSTM WND GST 2 SSW BIG TIMBER 45.81N 109.98W
12/07/2021 M64.00 MPH SWEET GRASS MT AWOS
SEVERAL GUSTS 59+ MPH SINCE 7PM.
&&
TRCPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BILLINGS MT
152 AM MST WED DEC 08 2021
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0110 AM NON-TSTM WND GST 2 WSW LIVINGSTON 45.65N 110.60W
12/08/2021 M60.00 MPH PARK MT DEPT OF HIGHWAYS
&&
JKLPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BILLINGS MT
217 AM MST WED DEC 08 2021
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0121 AM NON-TSTM WND GST 6 ENE LIVINGSTON 45.70N 110.45W
12/08/2021 M59.00 MPH PARK MT ASOS
&&
JKLThe national radar mosaic for the moment the first event began.
1 high wind. Local standard time, as filed.
Winds gusted to 58 mph across the Melville 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, December 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: 992378.