Remotely Triggered Avalanche on Henderson Mountain, Cooke City

Henderson Mountain
Cooke City
Code
SS-ASr-R3-D2-O
Elevation
9500
Aspect
SW
Latitude
45.05240
Longitude
-109.94500
Notes

On the west side of Henderson Moutain, while ascending a low-angle slope toward a known avalanche path, we experienced several collapses. Halfway up the slope, Ian noted snowballs rolling down the hill and around the corner, we could see the debris that had come from the steep terrain above. We had a clear view of this slope near the snowmobiles and it had not avalanched when we began ascending. At some point from several hundred feet away, we remotely triggered the slope. The avalanche was ~150' wide, 2' deep and ran almost to the road. Across the gully, we could see large cracks but the slope did not avalanche. Above, cracking and collapsing continued and we got a view into the upper part of the gully and saw another crown of an avalanche that likely happened at the same time as the slope below. 

 

 

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Soft slab avalanche
Trigger
Skier
Trigger Modifier
r-A remote avalanche released by the indicated trigger
R size
3
D size
2
Bed Surface
O - Old snow
Problem Type
Persistent Weak Layer
Slab Thickness
18.0 inches
Vertical Fall
350ft
Slab Width
150.00ft
Weak Layer Grain type
Near surface faceted particles
Weak Layer grain size
2.00mm
Weak Layer Hardness
F
Snow Observation Source
Slab Thickness units
inches
Single / Multiple / Red Flag
Single Avalanche
Advisory Year