Avalanche on Andesite Peak

Location Name: 
Andesite Peak
Region: 
Donner Summit Area
Date and time of avalanche (best estimate if unknown): 
Thu, 01/07/2016 - 10:50
Location Map: 
United States
39° 21' 0.7992" N, 120° 21' 46.6956" W
See map: Google Maps
US


Red Flags: 
Recent loading by new snow, wind, or rain
Observation made by: Guide at Tahoe Mountain School
Avalanche Observations
Avalanche Type: 
Dry
Slab
Slope: 
35degrees
Trigger type: 
Snowboarder
Crown Height: 
1 ft
Aspect: 
East
Weak Layer: 
Storm Snow
Avalanche Width: 
30ft.
Terrain: 
Near Treeline
Elevation: 
8 000ft.
Bed Surface: 
Old Snow
Avalanche Length: 
50ft.
More detailed information about the avalanche: 

Avalanche on Andesite peak yesterday. Broke on a convex roll over steeper terrain on an Easterly aspect. Soft slab avalanche that slid on the new/old snow interface, most likely near surface facets.  SS-ARu-R2/D1-I

Also observed in the area was consistent, yet localized, collapsing on E-NE aspects at treeline around 8,000'. Shovel tilt test's revealed easy sheering on new/old snow interface 30-40cm down.

Avalanche Photos: 
Weather Observations
Blowing Snow: 
No
Cloud Cover: 
75% of the sky covered by clouds
Air temperature: 
Below Freezing
Wind Speed: 
Calm
Precipitation: 
Mixed rain and snow
Air temperature trend: 
Warming
Wind Direction: 
Southwest
Accumulation rate: 
None
More detailed information about the weather: 

A light mist in the morning deposited a thin, easily breakable crust on the snow surface.