Snowmobile triggered 3-5' deep hard slab at Lionhead

Targhee Creek
Lionhead Range
Code
HS-AMu-R4-D3-O
Elevation
9200
Aspect
N
Latitude
44.74130
Longitude
-111.37400
Notes

A rider triggered a huge avalanche in the uppermost reaches of Targhee creek. We discovered it on our way out. The best we could tell looking at their tracks was that they had no idea they triggered it, even though part of their tracks were swept away. 

 

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Hard slab avalanche
Trigger
Snowmobile
Trigger Modifier
u-An unintentional release
R size
4
D size
3
Bed Surface
O - Old snow
Problem Type
Persistent Slab
Slab Thickness
48.0 inches
Vertical Fall
200ft
Slab Width
200.00ft
Weak Layer Grain type
Faceted Crystals
Weak Layer grain size
2.50mm
Attached Videos
Snow Observation Source
Slab Thickness units
inches
Single / Multiple / Red Flag
Single Avalanche
Advisory Year