20-21

Skier triggered avalanche NE of Cooke City

Zimmer Creek
Cooke City
Code
SS-ASu-R3-D2-I
Elevation
9800
Aspect
E
Latitude
45.09990
Longitude
-109.88400
Notes

A skier triggered a low angled slope (29-30 deg). It was new snow that failed on a layer of graupel. Crown was 6” to 2’ at its deepest. Broke 400’ wide, maybe 200’ vert. The skier triggered the slide on descent and was not aware of the avalanche until he stopped at the bottom of the run. Skier had a partner, rescue gear and was not caught.

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Soft slab avalanche
Trigger
Skier
Trigger Modifier
u-An unintentional release
R size
3
D size
2
Bed Surface
I - Interface between new and old snow
Problem Type
New Snow
Slab Thickness
30.0 centimeters
Vertical Fall
200ft
Slab Width
400.00ft
Weak Layer Grain type
Graupe
Attached Videos
Skier triggered avalanche, Cooke
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Single Avalanche
Advisory Year
20-21

Woody Ridge

Date
Activity
Skiing

I skied up Republic Creek this morning, and found all kinds of wind-affected, heavy snow. Stepping off the skin track in meadows consistently produced whumphing, and trees showed a few cms of settling around their bases overnight. I observed 4-5 natural slides on wind-loaded slopes, with crowns up to 3’. A pit on a west aspect around 9200’ had a dense slab of new snow overlying facets from our last bit of high pressure, and produced an ECTP13 at the new/old snow interface with a fast, clean propagation. I climbed 1-200’ above this, looked around at the mature whitebarks bowing in the wind, wondered what I was doing out there, and went home.

Region
Cooke City
Location (from list)
Republic Creek
Observer Name
Sam Reinsel

Natural Avalanche Mt. Republic

Mt Republic
Cooke City
Code
SS-N-R2-D2-I
Elevation
9000
Aspect
NW
Latitude
45.00170
Longitude
-109.95500
Notes

Multiple fresh avalanches observed on the drive into Cooke City. From email: "The recent dense snowfall seems to be avalanching wherever it's getting loaded by a heady SW wind. This was in the region below Republic, NW facing."

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Soft slab avalanche
Trigger
Natural trigger
R size
2
D size
2
Bed Surface
I - Interface between new and old snow
Problem Type
New Snow
Images
Natural Avalanche Republic
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Single Avalanche
Advisory Year
20-21

Natural Avalanche Mineral Mountain

Mineral Mountain
Cooke City
Code
SS-N-R2-D2-I
Elevation
9500
Latitude
45.03030
Longitude
-109.99800
Notes

Multiple fresh avalanches observed on the drive into Cooke City. From email: "The recent dense snowfall seems to be avalanching wherever it's getting loaded by a heady SW wind."

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Soft slab avalanche
Trigger
Natural trigger
R size
2
D size
2
Bed Surface
I - Interface between new and old snow
Problem Type
New Snow
Images
Natural Avalanche Mineral Mountain
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Single Avalanche
Advisory Year
20-21

Natural Avalanches Barronette Peak

Barronette Peak
Cooke City
Code
SS-N-R2-D2
Elevation
9500
Aspect
E
Latitude
44.97520
Longitude
-110.08700
Notes

Multiple fresh avalanches observed on the drive into Cooke City. From email: "The recent dense snowfall seems to be avalanching wherever it's getting loaded by a heady SW wind."

Number caught
0
Number buried
0
Avalanche Type
Soft slab avalanche
Trigger
Natural trigger
R size
2
D size
2
Problem Type
New Snow
Images
Natural Avalanche Barronette Peak 2
Natural Avalanche Barronette Peak 1
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Multiple Avalanches
Advisory Year
20-21

Multiple fresh avalanches observed on the drive into Cooke City. From email: "The recent dense snowfall seems to be avalanching wherever it's getting loaded by a heady SW wind." Photo: G Antonioli

Avalanche Details: Natural Avalanche Mt. Republic
Forecast link: GNFAC Avalanche Forecast for Wed Dec 23, 2020GNFAC Avalanche Forecast for Thu Dec 24, 2020
Cooke City, 2020-12-22
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    • Natural Wind Slab - Overlook Mountain

    Overlook Mountain
    Northern Gallatin
    Code
    SS-N
    Aspect
    W
    Latitude
    45.40500
    Longitude
    -110.94200
    Notes

    From email: "I heard and saw a natural avalanche across the basin on the west-facing slopes below Overlook Mountain, I also observed recent avalanche debris below “The G Spot” which is in a couloir below Overlook. Even though there isn’t any recent snow, the snow that is there is getting actively blown around."

    Number of slides
    1
    Number caught
    0
    Number buried
    0
    Avalanche Type
    Soft slab avalanche
    Trigger
    Natural trigger
    Slab Thickness units
    centimeters
    Single / Multiple / Red Flag
    Single Avalanche
    Advisory Year
    20-21
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