Active Wind Slabs on Andesite Peak

Location Name: 
Andesite Peak
Region: 
Donner Summit Area
Date and time of avalanche (best estimate if unknown): 
Tue, 01/19/2016 - 12:30
Location Map: 
United States
39° 21' 6.3432" N, 120° 21' 55.3932" W
See map: Google Maps
US


Red Flags: 
Recent avalanche activity
Whumphing noises, shooting cracks, or collapsing
Recent loading by new snow, wind, or rain
Obvious avalanche path
Observation made by: Forecaster
Avalanche Observations
Avalanche Type: 
Dry
Slab
Slope: 
38degrees
Trigger type: 
Skier
Aspect: 
Northeast
Weak Layer: 
Storm Snow
Terrain: 
Near Treeline
Elevation: 
8 000ft.
Bed Surface: 
Storm Snow
Number of similar avalanches: 
3
More detailed information about the avalanche: 

3 separate avalanches all intentionally triggered by cornice kicks.  NE-E aspects, 8000-8200', near treeline,  36-42 degrees steepness.  Sensitive wind slabs failing on a density change near the old snow/new snow interface.  New storm snow of 6'' with wind slabs up to 2' deep.  In 2 of the cases propagation was wide and avalanches ran full path down into the trees(see photos and video).

Video:  300' wide and 250' downslope wind slab avalanche. 

Photos 1&2:  Small wind slab triggered by oven sized pieces of cornice

Photos 3, 4, & 5:  Large wind slab avalanche triggered by an oven sized piece of cornice. Photo #4 is enhanced to show the debris more clearly. 

Avalanche Photos: 
Avalanche observation video: 

IMG 1644

Weather Observations
Blowing Snow: 
Yes
Cloud Cover: 
100% of the sky covered by clouds
Air temperature: 
Above Freezing
Wind Speed: 
Strong
Precipitation: 
Mixed rain and snow
Air temperature trend: 
Static
Wind Direction: 
Southwest
Accumulation rate: 
Less than 1 in. per hour
More detailed information about the weather: 

Snow showers in the morning hours tapering off with rain developing around 12pm.  Rain level up to around 8000' in the mid afternoon.  SW winds 30-40mph.