Avalanche in Montana, January 1, 2020

Name: Avalanche in Montana, January 1, 2020
Start: 2020-01-01T14:00
End: 2020-01-01T14:05
Location: Montana

January 1, 2020 · NWS MSO · 1 event in 1 county or zone

Heavy snow and wind loading on weak snow layers New Year's Eve day led to an unstable snowpack to begin the New Year.

Where it happened

Every event with a place to put it; 1 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: 2
Injuries: 0
Property damage: None recorded
Crop damage: None recorded
Events: 1

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 MSO wrote it up.

Heavy snow and wind loading on weak snow layers New Year's Eve day led to an unstable snowpack to begin the New Year.

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 Missoula, MT wrote its last area forecast discussion before the first event at Jan 1, 3:17 AM MST, 10 hours 43 minutes earlier.

Area forecast discussion, Jan 1, 3:17 AM MST, 10 hours 43 minutes before

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In the hours before

Local storm report, Jan 1, 10:22 AM MST, 3 hours 38 minutes before

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Local storm report, Jan 1, 10:23 AM MST, 3 hours 37 minutes before

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Local storm report, Jan 1, 10:25 AM MST, 3 hours 35 minutes before

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Local storm report, Jan 1, 10:28 AM MST, 3 hours 32 minutes before

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Local storm report, Jan 1, 10:43 AM MST, 3 hours 17 minutes before

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Local storm report, Jan 1, 10:44 AM MST, 3 hours 16 minutes before

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The radar

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

Open the radar archive at this moment

Event by event

1 avalanche. Local standard time, as filed.

Avalanche, Potomac / Seeley Lake Region

When: January 1, 2:00 PM MST to 2:05 PM MST
Where: Potomac / Seeley Lake Region forecast zone
Deaths: 2 direct, 0 indirect
Reported by: Park/Forest Service
Coordinates: 46.986, -113.597 (the zone’s center; the record gives no point)

Three snowmobilers were involved in an avalanche approximately 1 mile northwest of Lake Dinah, or about 12 miles northwest of Seeley Lake. The riders were caught and carried a short distance; two were fully buried, and one extricated himself after being separated from his snowmobile. The dimensions of the avalanche were 560 feet long, 100 feet wide, and an average of 6 feet deep. The two riders who were fully buried could not be saved, thus two fatalities occurred as a result of the avalanche.

The people who died

As the offices recorded each death: direct deaths were caused by the weather itself, indirect ones by something it set in motion.

Event	Date	Age	Sex	Where	Kind
Avalanche, Potomac / Seeley Lake Region	2020-01-01	26	Male	Outside/Open Areas	Direct
Avalanche, Potomac / Seeley Lake Region	2020-01-01	24	Male	Outside/Open Areas	Direct

What these are

Avalanche: A mass of snow sliding down a mountainside that caused a death, an injury or damage.

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, January 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 2026-09-30. Each event’s entry at NCEI: 866919.