Skier Triggered Storm Slab on Andesite

Location Name: 
Andesite Peak
Region: 
Donner Summit Area
Date and time of avalanche (best estimate if unknown): 
Sat, 12/24/2016 - 11:30
Location Map: 
United States
39° 21' 1.2492" N, 120° 21' 44.8416" W
US


Red Flags: 
Recent avalanche activity
Whumphing noises, shooting cracks, or collapsing
Recent loading by new snow, wind, or rain
Obvious avalanche path
Terrain Trap

Observation made by: Forecaster
Avalanche Observations
Avalanche Type: 
Dry
Slab
Slope: 
40degrees
Trigger type: 
Skier
Crown Height: 
1 ft
Aspect: 
Northeast
Weak Layer: 
Storm Snow
Avalanche Width: 
75ft.
Terrain: 
Below Treeline
Elevation: 
7 800ft.
Bed Surface: 
Storm Snow
Avalanche Length: 
100ft.
Number of people caught: 
1
Number of partial burials: 
0
Number of full burials: 
0
More detailed information about the avalanche: 

A group of 2 skiers skied down from the summit of Andesite Peak and into some steep, open. below treeline terrain.  1 skier triggered a storm slab avalanche that appeared to have failed at the old snow/new snow interface.  Crown was 8'' to 16'' deep, on a convex rollover in steep terrain.  Avalanche was approximately mid slope and partially on a steep rock feature.  Skier was taken for a ride and had to search for some lost equipment.  See Andesite Peak snowpack observation for more info on snowpack. 

I was in the immediate area of this avalanche but did not witness it.  The details were passed on to me from another party in the area.

Avalanche Photos: 
Avalanche observation video: 
Weather Observations
Blowing Snow: 
No
Cloud Cover: 
50% of the sky covered by clouds
Air temperature: 
Below Freezing
Wind Speed: 
Calm
Precipitation: 
None
Air temperature trend: 
Static