23-24

Cracking and Collapsing in Middle Basin

Middle Basin
Northern Madison
Code
Latitude
45.33400
Longitude
-111.38300
Notes

From obs: "Stepping off my skis I sank to the ground when over in middle basin. There was widespread cracking, collapsing, and whoompfing. A few smaller natural avalanches."

Number of slides
0
Number caught
0
Number buried
0
Snow Observation Source
The mountains are alive
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Red Flag
Advisory Year
23-24

The mountains are alive

Date
Activity
Skiing

Today's walk was difficult. Stepping off my skies I sank to the ground when over in middle basin. There was widespread cracking, collapsing, and whoompfing. A few smaller natural avalanches but not as many as I had expected with the feedback we were getting. Still great to get out.

Region
Northern Madison
Location (from list)
Middle Basin
Observer Name
Nelson VanTassel

Pits in Bradleys

Date
Activity
Skiing

Dug pits both above and below Bradley Meadows with a Fundamentals Course. We got ECTNx5 down 30cm on the facets which were first buried Jan 5th. The snow overlying the facets was soft (fist to four finger).

Region
Bridger Range
Location (from list)
Bradley Meadow
Observer Name
Nata de Leeuw

Snowmobiler triggered slide, Island Park

Sawtelle Peak
Island Park
Code
SS-R2-D2-O
Elevation
9600
Aspect
SE
Latitude
44.56110
Longitude
-111.44300
Notes

A snowmobiler triggered slide occurred yesterday below Sawtelle Peak. It broke on the buried surface hoar and facets about 1.5 feet under the surface. 

The avalanche:

44.55581, -111.45085
El 9,286'
 
HS - 143 cm
Surf hoar 96-95 cm
Slab was 18-24" deep
Not really wind loaded, but it looks like winds wrap around that face.
About 150' wide
about 300' vertical
Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Soft slab avalanche
Trigger Modifier
u-An unintentional release
R size
2
D size
2
Bed Surface
O - Old snow
Problem Type
Persistent Weak Layer
Slab Thickness
50.0 centimeters
Vertical Fall
300ft
Slab Width
150.00ft
Weak Layer Grain type
Surface Hoar
Weak Layer Hardness
F
Images
Crown as seen from the Sawtelle Road
Crown of the avalanche
Looking up the path, 38 degrees steep
Attached Videos
Heads Up, We Are Seeing Avalanches, Island Park - 19 Jan
Snow Observation Source
An avalanche and instability
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Single Avalanche
Advisory Year
23-24

On Sawtelle Peak, Island Park, when the clouds lifted we could see a crown of a snowmobiler triggered slide that occurred yesterday. It broke on the buried surface hoar and facets about 1.5 feet under the surface. Recent snow and wind-loading has created dangerous avalanche conditions. Photo: GNFAC

Avalanche Details: Snowmobiler triggered slide, Island Park
Island Park, 2024-01-19
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    • On Sawtelle Peak, Island Park, when the clouds lifted we could see a crown of a snowmobiler triggered slide that occurred yesterday. It broke on the buried surface hoar and facets about 1.5 feet under the surface. Recent snow and wind-loading has created dangerous avalanche conditions. Photo: GNFAC

    Avalanche Details: Snowmobiler triggered slide, Island Park
    Forecast link: GNFAC Avalanche Forecast for Sat Jan 20, 2024
    Island Park, 2024-01-19
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  • Original

    • On Sawtelle Peak, Island Park, when the clouds lifted we could see a crown of a snowmobiler triggered slide that occurred yesterday. It broke on the buried surface hoar and facets about 1.5 feet under the surface. Recent snow and wind-loading has created dangerous avalanche conditions. Photo: GNFAC

    Avalanche Details: Snowmobiler triggered slide, Island Park
    Island Park, 2024-01-19
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  • Small 150px
  • Original

    • An avalanche and instability

    Date
    Activity
    Snowmobiling

    We dug pits and rode on Sawtelle Peak. At 9,100 feet we had unstable test results (ECTP13 x 5; ECTP10 x2; CT4, Q1). When the clouds lifted we could see a crown of a snowmobiler triggered slide that occured yesterday. It broke on the buried surface hoar and facets about 1.5 feet under the surface. Recent snow and wind-loading has created dangerous avalanche conditions.

    The avalanche:

    44.55581, -111.45085
    El 9,286'
     
    HS - 143 cm
    Surf hoar 96-95 cm
    Slab was 18-24" deep
    Not really wind loaded, but it looks like winds wrap around that face.
    About 150' wide
    about 300' vertical
    Region
    Island Park
    Location (from list)
    Sawtelle Peak
    Observer Name
    Doug Chabot
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