Second Slide avalanche

Location Name: BNSF Avalanche Safety - Running Rabbit Mtn GNP Observation date: Sunday, January 9, 2022 - 19:00	Is this an Avalanche Observation: Yes

Observation made by: Public

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Visited the crown of the Second Slide avalanche that ran in the night on Jan. 7th/8th.
Objectives were to size up the crown in Second Slide and obtain a profile of the snowpack there. Also went to look for additional avalanche activity, observe the recent wind-loading, and assess snowpack stability.

The avalanche in Second Slide ran sometime around 0030 hours on Jan. 8th. Debris was deposited on the grade and was 6-15’ deep and 60’ wide - a Destructive size 2 of 5
- This avalanche initiated in the uppermost starting zone at 5400’ on a SE aspect.
- The crown was about 300’ wide, 1-3’ thick, and already partially filled back in with wind-transported snow (photo).
- This was a wind slab that formed from the recent westerly winds and about 1-finger hardness. It failed on a layer of buried facets (see crown profile).
- An extended column test did not yield any fractures on the avalanche failure layer, but a compression test resulted in CT14 Q3 on said layer.
We encountered another avalanche on our descent on an easterly aspect at about 5200’. Another wind slab that likely failed on the same layer of buried facets. This was also a Destructive size 2 of 5 and associated debris ran several hundred feet through thick trees terminating well-above the rail grade.
Our most recent rain crust from the Jan 7th/8th storm is present on the snowpack surface from the Canyon floor up to about 4600’ elevation.
A layer of buried facets was widespread during our tour. Below 5000’ these facets were resting on top of the mid-Dec. crust. Above this elevation, no crust was present near the facet layer.
The wind-loading from the recent storm was impressive with slabs 1-4’ thick. We cut several of these recent wind slabs and had mostly unreactive results – no cracking or whumpfing, but some collapsing into the facets at lower elevations.

Mostly sunny skies with no precipitation and light to moderate westerly winds.
Daytime high air temperatures reached the mid-30s °F on the Canyon floor and the low to mid-20s °F at upper elevations

Snowpack, Avalanche, Weather Images:

Travel Details

Region:

Flathead Range/Glacier National Park - John F. Stevens Canyon

Activity:

Skiing

Snowpack Details

Snowpack and Weather Details:

Terrain

Elevation of observation:

3500-5000 ft

5000-6500 ft

Aspect(s) of observation:

Avalanche Details

Avalanche Details:

Date and Time of Avalanche:

Tuesday, December 8, 2020 - 00:00

Number of avalanches:

Avalanche Type:

Soft Slab

Failure Plane/Weak Layer:

Old snow

More information or comments about the avalanche:

Debris to the rail - 60' wide and 6-15' deep

Trigger

Trigger:

natural

Terrain

Aspect:

Southeast

Starting Elevation:

near-treeline

Size

Destructive Size:

D2 Could bury, injure, or kill a person.

Relative Size:

R4 Large

Crown Height:

2 ft

Avalanche Length (Vertical Run):

1200ft.

Avalanche Width (Average width):

300ft.

Avalanche Location:

Date and Time of Avalanche:

Saturday, January 8, 2022 - 01:00

Number of avalanches:

Avalanche Type:

Soft Slab

Failure Plane/Weak Layer:

Old snow

More information or comments about the avalanche:

Ran through several hundred feet of thick trees. Not really visible from the Highway, we skied into the debris and could make out a little details of the crown above.

Trigger

Trigger:

natural

Terrain

Aspect:

East

Starting Elevation:

near-treeline

Size

Destructive Size:

D2 Could bury, injure, or kill a person.

Relative Size:

R3 Medium

Crown Height:

2 ft

Avalanche Length (Vertical Run):

500ft.

Avalanche Width (Average width):

150ft.

Avalanche Location:

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