Skier triggered avalanche on Andesite Ridge

Location Name: 
Andesite Ridge
Region: 
Donner Summit Area
Date and time of avalanche (best estimate if unknown): 
Sat, 01/16/2016 - 12:00
Location Map: 
United States
39° 20' 36.186" N, 120° 21' 12.7044" W
See map: Google Maps
US



Observation made by: Public
Avalanche Observations
Avalanche Type: 
Dry
Slab
Trigger type: 
Skier
Aspect: 
Northeast
Weak Layer: 
Old Snow
Terrain: 
Near Treeline
Elevation: 
7 550ft.
Bed Surface: 
Old Snow
Number of people caught: 
2
More detailed information about the avalanche: 

Triggered a slide on the northeast aspect. Me and one other person on slope. Both fine. I skied out to the north and the other person was riding the top and grabbed a tree. 3 others on top skied down the southwest aspect after the slide and were in radio contact with us.

We had previously dug a pit on the southwest aspect of Castle and skied that fine. We dug a pit at the top a bit north of the fun shack's former location. No failure on an ECT but we did notice a week layer 120cm down upon shovel shear, everything else was nicely adhering. I think it was the rocks that created enough of a slip plane with the weight of two skiers on it. There also was considerable snowballs rolling down a few seconds before the slide.

Weather Observations
Cloud Cover: 
100% of the sky covered by clouds
Air temperature: 
Above Freezing
Precipitation: 
Rain
Air temperature trend: 
Static