Natural Avalanches on Andesite Ridge

Location Name: 
Andesite Ridge
Region: 
Donner Summit Area
Date and time of avalanche (best estimate if unknown): 
Wed, 01/04/2017 - 13:00
Location Map: 
United States
39° 20' 33.936" N, 120° 21' 6.8364" 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
Terrain Trap
Observation made by: Forecaster
Avalanche Observations
Avalanche Type: 
Dry
Slab
Slope: 
35degrees
Trigger type: 
Natural
Crown Height: 
3 ft
Aspect: 
Northeast
Weak Layer: 
Storm Snow
Avalanche Width: 
125ft.
Terrain: 
Below Treeline
Elevation: 
7 500ft.
Avalanche Length: 
200ft.
Number of similar avalanches: 
3
More detailed information about the avalanche: 

Several natural avalanches observed in the Andesite Ridge area of Donner Summit.  The largest was a wind slab avalanche on a NE/E aspect, 35 degree slope, with up to a 3' crown.  This avalanche wrapped around a rock feature and was approximately 125' wide by 200' downslope with avalanche debris running down into the trees.  Most of these avalanches appeared to be running within the new storm snow.  Total storm snow in this area was 4+ feet.

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