21-22

From obs 2/27/22: "Skied Flanders mountain today. Dug a snowpit on a SE facing 24 deg slope at 9700 feet. ECTN24 30cm down on a layer of facets just under an ice crust. Snow above the ice crust was 4F- at most and not hard enough for anything to propagate. Winds were moderate and gusty, transporting a decent amount of snow but not really forming any slabs other than at the ridgeline. I triggered a shallow 2-3cm deep windslab about 20 feet wide just below the ridgeline. I was not on a steep slope, so it barely moved.... didn't see any other signs of instability." Photo: M. Lavery

Northern Gallatin, 2022-02-28

Collapse and "whumph" on Scotch Bonnet

Scotch Bonnet
Cooke City
Code
SS-AS-O
Elevation
10150
Aspect
SW
Latitude
45.07330
Longitude
-109.94800
Notes

On 2/27/22 while touring near the top of Rasta Chutes on Scotch Bonnet Mtn. near Cooke City we triggered a ccollapseof the snowpack and heard a loud "whumph". A 8-10" sslabfailed and propagated on a layer of weak, sugary facets on top of a hard melt-freeze crust. Estimated 40 feet wide.

Number of slides
0
Number caught
0
Number buried
0
Avalanche Type
Soft slab avalanche
Trigger
Skier
Bed Surface
O - Old snow
Problem Type
Persistent Weak Layer
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Red Flag
Advisory Year

Small skier and rider triggered slides near Cooke

Lulu Pass
Cooke City
Code
SS-AS-R1-D1
Elevation
10000
Aspect
E
Latitude
45.07090
Longitude
-109.95800
Notes

Photo is of a slide that was triggered by a skier on 2/26/22 on Rob's Knob near Lulu Pass. We saw 3 other similar sized slides on 2/27/22 while riding between Lulu Pass and Goose Creek.

Number of slides
4
Number caught
0
Number buried
0
Avalanche Type
Soft slab avalanche
Trigger
Skier
R size
1
D size
1
Problem Type
Persistent Weak Layer
Slab Thickness
10.0 inches
Vertical Fall
250ft
Slab Width
30.00ft
Slab Thickness units
inches
Single / Multiple / Red Flag
Multiple Avalanches
Advisory Year

Snowmobile triggered slide near Goose Creek, Cooke

Goose Creek
Cooke City
Code
SS-AMu-R3-D1.5-O
Elevation
9000
Aspect
SE
Latitude
45.09230
Longitude
-109.95100
Notes

This slide was triggered by a sledder on 2/26/22 around 1pm near Goose Creek outside Cooke City.

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Soft slab avalanche
Trigger
Snowmobile
Trigger Modifier
u-An unintentional release
R size
3
D size
1.5
Bed Surface
O - Old snow
Problem Type
Persistent Weak Layer
Slab Thickness
18.0 inches
Vertical Fall
50ft
Slab Width
75.00ft
Slab Thickness units
inches
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

Snowmobile triggered hard slab, Sheep Mtn., Cooke

Sheep Mountain
Cooke City
Code
HS-AM-R2-D1.5-O
Elevation
10000
Aspect
NW
Latitude
45.07220
Longitude
-109.92800
Notes

We saw this avalanche the afternoon of 2/27/22, on a north facing slope on Sheep Mtn. near Cooke City. It appeared less than 24 hours old and likely snowmobile triggered.

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Hard slab avalanche
Trigger
Snowmobile
R size
2
D size
1.5
Bed Surface
O - Old snow
Problem Type
Persistent Weak Layer
Slab Thickness
30.0 inches
Vertical Fall
30ft
Slab Width
100.00ft
Slab Thickness units
inches
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

We saw this avalanche the afternoon of 2/27/22, on a north facing slope on Sheep Mtn. near Cooke City. It appeared less than 24 hours old and likely snowmobile triggered. Photo: GNFAC

Cooke City, 2022-02-27