22-23

Big Avalanche Crown, N. Absaroka Range

Arrastra Creek
Out of Advisory Area
Code
HS-N-R4-D3-O
Elevation
10200
Aspect
SE
Latitude
45.26430
Longitude
-110.61700
Notes

From email: "Saw this recent crown while xc skiing out above Mill Creek today.  It's on the east-southeast aspect of Peak 10526 east of Emigrant Peak at ~10,200'.  In what I like to call the Arrastra Ridge Avalanche Observatory Plot*.  The photo is taken approximately 5 miles in line of sight from the crown.  It is roughly 1000' wide.  If I had to guess, the crown is 10'+ tall—definitely a very destructive avalanche. I won't venture a guess on the rating.  I'd bet good money it ran all the way to the lake at the head of Burnt Creek and rearranged some timber.

*If one wanted to create a laboratory for observing large, regularly occurring naturally triggered avalanches, this would be one of the best locations in SW MT."

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Hard slab avalanche
Trigger
Natural trigger
R size
4
D size
3
Bed Surface
O - Old snow
Problem Type
Persistent Weak Layer
Slab Thickness
120.0 inches
Slab Width
1000.00ft
Snow Observation Source
Slab Thickness units
inches
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

Natural avalanche Naya Nuki

Naya Nuki Bowl
Bridger Range
Code
N-R2-D2
Elevation
9000
Aspect
E
Latitude
45.88830
Longitude
-110.95900
Notes

A group of skiers saw a natural avalanche on an east, facing slope off of Naya Nuki Mountain in the Bridger range. It likely avalanched early in the morning on April 2.

Number of slides
1
Number caught
0
Number buried
0
Trigger
Natural trigger
R size
2
D size
2
Problem Type
Wind-Drifted Snow
Slab Thickness
42.0 inches
Snow Observation Source
Slab Thickness units
inches
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

Lionhead observations 4/2/2023

Date
Activity
Skiing

We skied/snowboarded in the Lionhead range today and dug a pit on a southeast facing slope at 8900 feet. There was about 3" of fresh on top of a 3/4" thick crust. Then about 11 inches of 1-4 finger density snow, a hard 3/4" thick crust, a 1" layer of snow, and a third 1/2" thick crust. Below this was 30 " of one finger density snow to the bottom of our pit, (and 32" of snow below that).

We got ECTN4 at 6" below the surface along an unidentified thin layer, and ECTP11 that slid on top of the second ice crust (about 14" below the surface).

Riding conditions were better than the crusty layers might suggest. We stuck to the trees, less-than-30-degree slopes, and avoided slopes leading to terrain traps. We did not observe any avalanche activity.

Region
Lionhead Range
Location (from list)
Hebgen Lake
Observer Name
Alex

Natural Avalanches near Battle Ridge

Battle Ridge
Bridger Range
Code
N-R2-D2
Latitude
45.88250
Longitude
-110.88200
Notes

From IG: A group of writers reported seeing three new natural avalanches on April 1. 

Number of slides
1
Number caught
0
Number buried
0
Trigger
Natural trigger
R size
2
D size
2
Problem Type
Wind-Drifted Snow
Snow Observation Source
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

Tobacco Roots Avalanche

Tobacco Root Mountains
Out of Advisory Area
Code
HS-N-R3-D2.5
Latitude
45.52890
Longitude
-112.01800
Notes

From IG: “North meadow creek tobacco roots today“

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Hard slab avalanche
Trigger
Natural trigger
R size
3
D size
2.5
Problem Type
Persistent Weak Layer
Snow Observation Source
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

Natural Avalanche on Climax Path

Woody Ridge
Cooke City
Code
HS-N-R3-D3-O
Elevation
10000
Aspect
E
Latitude
44.97390
Longitude
-109.92400
Notes

From email: "Observed very limited terrain due to vis. Saw this very large avalanche on Climax. The crown looks fresh, so it likely occurred the day or night of 4/1?
Hard to tell but the crown looks to be about 4-6’ deep at its deepest. The debris ran to the creek.
E aspect at 10000’.

There were also several smaller soft slab avalanches that ran on the lookers right side of Climax.

On 4/1 we had a large collapse on a SE aspect at 9800’ where the MF crust was present under 60cm of new snow.

Winds were L-M with consistent gusts to S on Saturday."

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Hard slab avalanche
Trigger
Natural trigger
R size
3
D size
3
Bed Surface
O - Old snow
Problem Type
Persistent Weak Layer
Slab Thickness
62.0 inches
Vertical Fall
1200ft
Snow Observation Source
Slab Thickness units
inches
Single / Multiple / Red Flag
Single Avalanche
Advisory Year