Two large, deep avalanches on Mt. Henderson near Cooke

Henderson Mountain
Cooke City
Code
HS-AMu-R2-D2-O
Elevation
10000
Aspect
NE
Latitude
45.05240
Longitude
-109.94500
Notes

Skiers reported: "Two new [trigger unknown] avalanches on the east side of Henderson today. The first photo is from this morning (12/27/19) around 11:00. The second one appears to be much deeper and I didn't notice it until I rode back by around 2:30, so it might have occurred while I was out skiing or I just missed it this morning."

From Dave and Doug's investigation on 29 Dec:

1. The lookers left avalanche was the deepest at 6' deep of Hard Slab. Estimated 150' wide and 300' vertical. It broke on facets near the ground.

2. The avalanche to the right was 3' deep and also broke on facets near the ground. It too was heavily wind-loaded. Estimated 250' wide and 300' vertical.

Number of slides
2
Number caught
0
Number buried
0
Avalanche Type
Hard slab avalanche
Trigger
Snowmobile
Trigger Modifier
u-An unintentional release
R size
2
D size
2
Bed Surface
O - Old snow
Problem Type
Persistent Weak Layer
Slab Thickness
36.0 inches
Vertical Fall
300ft
Slab Width
250.00ft
Weak Layer Grain type
Faceted Crystals
Weak Layer grain size
2.00mm
Weak Layer Hardness
4F
Slab Layer Grain Type
Rounding faceted particles
Slab Layer Grain Size
1.00mm
Slab Layer Hardness
1F
Slab Thickness units
inches
Single / Multiple / Red Flag
Multiple Avalanches
Advisory Year