High Wind in Montana, December 19 to 20, 2020

Name: High Wind in Montana, December 19 to 20, 2020
Start: 2020-12-19T08:32
End: 2020-12-20T15:44
Location: Montana

December 19 to 20, 2020 · NWS GGW · 6 events in 6 counties and zones

A fast jet stream aloft and a tight pressure gradient over the region, set up a favorable atmosphere for mixing most of those stronger winds down to the surface for many locations across northeast Montana.

Where it happened

Every event with a place to put it; 6 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.

Tornadoes
Tropical storms and surge
Floods
Wind
Hail
Winter weather
Heat and drought
Cold
Fire, smoke and dust
Marine and coastal
Other

Open the live radar over this ground

The toll

Deaths: 0
Injuries: 0
Property damage: None recorded
Crop damage: None recorded
Events: 6

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.

What happened

The episode as NWS GGW wrote it up.

What forecasters said that day

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 Glasgow, MT wrote its last area forecast discussion before the first event at Dec 19, 3:31 AM MST, 5 hours 1 minute earlier.

Area forecast discussion, Dec 19, 3:31 AM MST, 5 hours 1 minute before

Area Forecast Discussion
National Weather Service Glasgow MT
331 AM MST Sat Dec 19 2020

.DISCUSSION...

A trough of low pressure from the Canadian Rockies is pushing a
tight pressure gradient through the region today. The thickest
cloud cover correlates with the axis of surface low pressure as
well, along with a few virga showers across portions of central
Montana. This seems to be just enough light shower activity to
pull down some stronger winds from aloft, even now during the
overnight and early morning hours for locations such as Havre and
Zortman, where winds have already been gusting in excess of 40
mph recently. Will keep a close eye on it, but I do not expect any
stronger winds to gust through the area today. Widespread 30 to
40 mph winds are more likely. Also, this overnight low pressure
trough is pushing these gusty west and southwest winds in a
chinooking effect across those central Montana locations, where
temperatures are already climbing greater than 40 degrees during
these early morning hours.

Sunday, concerns are increasing for another round of strong and
gusty winds as tight gradient westerly flow from the Canadian
Rockies continues to push through our region. The atmosphere will
allow for some of those gusty winds to reach the surface, as
evidenced by strong model lapse rates in excess of 7 C/km mainly
along and south of US Highway 2 from late Sunday morning through
early Sunday evening. There does not seem to be any regional cold
air advection, but models are starting to pick up on a few
scattered snow or rain showers in the area, which could assist in
pulling those stronger winds from aloft, down to the surface. As
the onset of these expected winds for Sunday are still more than
24 hours away, felt it was best to continue with the High Wind
Watch for now, and let the next shift re-evaluate these threats
and decide if an upgrade to warning is needed. At this time, I
still do not have enough certainty.

As the winds diminish back down below 15 kts on Monday, a weak
ridge of high pressure moves in from the southwest to briefly
clear out skies and keep conditions dry overall.

Monday evening through Wednesday morning, a stronger and colder
low pressure trough from the west will sweep through our region.
For the earlier part of this system, most precipitation will be
confined to central Montana and southern Saskatchewan. Through
the latter part of the system, when the colder northwest winds
take over, better chances for light precipitation will move
through northeast Montana from NW to SE, with little impact, maybe
up to half an inch of new snow through Wednesday morning.

Wednesday evening through Christmas Day, a strong ridge of high
pressure will keep conditions across the region dry and warmer
than average.

&&

.AVIATION...

FLIGHT CONDITIONs:  VFR.

LLWS: Expected at all TAF sites through this afternoon, with 2000
ft. winds over 50 kts possible at times.

WINDS: S-SW 5-15 kts through early this morning. Winds shift later
this morning, and become W 15-25 kts through this afternoon and
evening. Expect gustier winds on Sunday.

SYNOPSIS: A dry weak front moves through the region today.
Temperatures don't really drop behind this front, and its main
impact will be a shift in wind direction and increase in wind
speeds. Winds taper off Saturday night as the atmosphere
decouples, but picks back up Sunday for another round

&&

.GLASGOW WATCHES/WARNINGS/ADVISORIES...
High Wind Watch Sunday afternoon for Central and Southeast
Phillips...Central and Southern Valley...Dawson...Garfield...
McCone...Northern Phillips...Northern Valley...Petroleum...
Prairie...Richland...Western Roosevelt...Wibaux.

High Wind Watch from Sunday morning through Sunday afternoon for
Southwest Phillips.

&&

weather.gov/glasgow

The radar

The national radar mosaic for the moment the first event began.

Open the radar archive at this moment

Event by event

6 high wind. Local standard time, as filed.

High Wind, Little Rocky Mountains

When: December 19, 8:32 AM MST to December 20, 8:32 AM MST
Where: Little Rocky Mountains forecast zone
Measured: 60 kt (69 mph) measured gust
Reported by: Department of Highways
Coordinates: 48.259, -107.913 (the zone’s center; the record gives no point)

In the town of Zortman and the immediate surrounding area in southwest Phillips County, wind gusts of 61 mph were measured for a few hours in the morning of the 19th. More widespread and longer-duration severe winds occurred on the 20th, especially downwind of the Little Rocky Mountains. Sustained winds there of at least 40 mph began mid-morning and continued through mid-afternoon. Severe wind gusts of at least 58 mph were common for 2 1/2 hours in the morning, then again for half an hour in the afternoon. The peak wind gust of 69 mph was recorded at the Malta South US-191 DOT site (MTMAL), at 9:41 MST on the 20th.

High Wind, Central and Southern Valley

When: December 19, 12:44 PM MST to December 20, 3:44 PM MST
Where: Central and Southern Valley forecast zone
Measured: 59 kt (68 mph) measured gust
Reported by: RAWS
Coordinates: 48.365, -106.667 (the zone’s center; the record gives no point)

Severe wind gusts of at least 58 mph were measured during the afternoon on both the 19th and the 20th at the King Coulee RAWS site (KIGM8). The peak wind gust of 68 mph was recorded at 14:44 MST on the 20th.

High Wind, Wibaux

When: December 19, 1:08 PM MST to December 20, 3:14 PM MST
Where: Wibaux forecast zone
Measured: 65 kt (75 mph) measured gust
Reported by: Department of Highways
Coordinates: 46.965, -104.249 (the zone’s center; the record gives no point)

At the Beaver Hill I-94 DOT site (MTBVR), severe wind gusts of at least 58 mph were common during the afternoon hours, both on the 19th and the 20th. The peak wind gust of 75 mph was recorded at 13:54 MST on the 20th.

High Wind, Dawson

When: December 19, 2:15 PM MST to December 20, 2:00 PM MST
Where: Dawson forecast zone
Measured: 56 kt (64 mph) measured gust
Reported by: Mesonet
Coordinates: 47.266, -104.899 (the zone’s center; the record gives no point)

At the Glendive BLM mesonet site (MTM28), located 5 ESE Hoyt, severe wind gusts of at least 58 mph were measured during the afternoon both on the 19th and 20th. The peak wind gust of 64 mph was recorded at 14:00 MST on the 20th.

High Wind, Garfield

When: December 20, 11:08 AM MST to 2:08 PM MST
Where: Garfield forecast zone
Measured: 58 kt (67 mph) measured gust
Reported by: ASOS
Coordinates: 47.278, -106.993 (the zone’s center; the record gives no point)

Across western and central portions of Garfield County, severe wind gusts of at least 58 mph were common from late morning through early afternoon on the 20th. The peak wind gust of 67 mph was recorded at the Jordan airport ASOS site (KJDN) at 13:48 MST.

High Wind, Petroleum

When: December 20, 1:54 PM MST to 2:54 PM MST
Where: Petroleum forecast zone
Measured: 50 kt (58 mph) measured gust
Reported by: Mesonet
Coordinates: 47.118, -108.250 (the zone’s center; the record gives no point)

At the Winnett mesonet site (GGWWT), peak wind gusts of 58 mph were recorded for a few hours during the afternoon of the 20th.

What these are

High Wind: Sustained non-thunderstorm winds of 40 mph or more for an hour, or gusts of 58 mph or more.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

Every storm in Montana in 2020 Every state in 2020 This day in weather history Warnings in Montana, December 2020

Sources

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: 934917, 934924, 934933, 934925, 934921, 934918.