19-20

Large natural avalanche on Mt. Fox, Cooke City

Mt Fox
Cooke City
Code
HS-N-R4-D3-G
Aspect
NE
Latitude
45.12120
Longitude
-109.93000
Notes

From an email:

From afar, observed a large R4/5 D3, to the ground, off of the entire NE shoulder of Fox Mtn. (see attached photo) as well as a couple of scattered R1/D1 wind slabs on upper elevations on E/NE aspects. 

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
G - Ground
Problem Type
Wind-Drifted Snow
Images
Large natural avalanche on Mt. Fox, Cooke City
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Single Avalanche
Advisory Year
19-20

From an email:

From afar, observed a large R4/5 D3, to the ground, off of the entire NE shoulder of Fox Mtn. (see attached photo) as well as a couple of scattered R1/D1 wind slabs on upper elevations on E/NE aspects. 

Avalanche Details: Large natural avalanche on Mt. Fox, Cooke City
Forecast link: GNFAC Avalanche Forecast for Thu Jan 16, 2020
Cooke City, 2020-01-15
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    • From an observation:

    Once in the bottom of Bear Basin, we could see a much larger avalanche that looked to be 1-2 days old. Its disjointed crown was some 150ft wide, but it was hard to tell how deep it was, as its crown was fairly far away and partly blown back in. Parts of the slide ran on the ground layer of facets but looked to be the result of wind load. Photo: C. Kussmaul

    Avalanche Details: Bat Ears Couloir and Bear Basin avalanches
    Forecast link: GNFAC Avalanche Forecast for Thu Jan 16, 2020
    Northern Madison, 2020-01-15
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    • From an observation:

    Once in the bottom of Bear Basin, we could see a much larger avalanche that looked to be 1-2 days old. Its disjointed crown was some 150ft wide, but it was hard to tell how deep it was, as its crown was fairly far away and partly blown back in. Parts of the slide ran on the ground layer of facets but looked to be the result of wind load. Photo: C. Kussmaul

    Avalanche Details: Bat Ears Couloir and Bear Basin avalanches
    Northern Madison, 2020-01-15
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    • Bat Ears Couloir and Bear Basin avalanches

    Bear Basin
    Northern Madison
    Code
    SS-ASc
    Aspect
    NW
    Latitude
    45.34530
    Longitude
    -111.37500
    Notes

    From an observation form:

    An intentional ski cut at the top of Bat Ears couloir produced a windslab avalanche with a crown 4-8inches deep and ran about as wide as the couloir. We then continued to ski down. Once in the bottom of Bear Basin, we could see a much larger avalanche that looked to be 1-2 days old. Its disjointed crown was some 150ft wide, but it was hard to tell how deep it was, as its crown was fairly far away and partly blown back in. Parts of the slide ran on the ground layer of facets but looked to be the result of wind load.

    I do not have pictures of the Bat Ears crown that we triggered. We exited via Bear basin with our tails between our legs, and hope this bad idea on our part can help others make terrain choices this weekend.

    Number caught
    0
    Number buried
    0
    Avalanche Type
    Soft slab avalanche
    Trigger
    Skier
    Trigger Modifier
    c-A controlled or intentional release by the indicated trigger
    Problem Type
    Wind-Drifted Snow
    Images
    Bear Basin natural avalanche_2
    Bear Basin natural avalanche_1
    Slab Thickness units
    centimeters
    Single / Multiple / Red Flag
    Multiple Avalanches
    Advisory Year
    19-20

    From e-mail: "Skiers triggered two separate slides on south Saddle this afternoon. we witnessed the smaller slide to the lookers right of the big slide, the bigger one happened later apparently... The first smaller slide was caused by a ski cut near the trees, fracture was about 2 feet, soft slab that seemed to run on a thin sun crust. below the sun crust was also very weak and sugary. Not sure when the second skier went farther out and triggered the whole bowl, but they got lucky!!" Photo: T. Andersen

    Avalanche Details: Skier triggered avalanche near Saddle Peak
    Bridger Range, 2020-01-15
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    • From e-mail: "Skiers triggered two separate slides on south Saddle this afternoon. we witnessed the smaller slide to the lookers right of the big slide, the bigger one happened later apparently... The first smaller slide was caused by a ski cut near the trees, fracture was about 2 feet, soft slab that seemed to run on a thin sun crust. below the sun crust was also very weak and sugary. Not sure when the second skier went farther out and triggered the whole bowl, but they got lucky!!" Photo: T. Andersen

    Avalanche Details: Skier triggered avalanche near Saddle Peak
    Forecast link: GNFAC Avalanche Forecast for Thu Jan 16, 2020
    Bridger Range, 2020-01-15
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    • A couple of thin, natural avalanches near Cooke City

    Mineral Mountain
    Cooke City
    Code
    SS-N
    Elevation
    9600
    Aspect
    SE
    Latitude
    45.03030
    Longitude
    -109.99800
    Notes

    Photo attached of a couple thin, natural slab avalanches near Cooke this morning.  SE aspects of Mineral Mtn., around 9,600'.

    Number caught
    0
    Number buried
    0
    Avalanche Type
    Soft slab avalanche
    Trigger
    Natural trigger
    Problem Type
    New Snow
    Images
    Thin, natural slab avalanches near Cooke City
    Slab Thickness units
    centimeters
    Single / Multiple / Red Flag
    Multiple Avalanches
    Advisory Year
    19-20
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