Natural Avalanche on Andesite Ridge

Location Name: 
Andesite Ridge
Region: 
Donner Summit Area
Date and time of avalanche (best estimate if unknown): 
Mon, 02/20/2017 - 12:00
Location Map: 
United States
39° 20' 36.2796" N, 120° 21' 10.6992" 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
Trigger type: 
Natural
Aspect: 
Northeast
Terrain: 
Below Treeline
Elevation: 
7 500ft.
More detailed information about the avalanche: 

Natural storm slab avalanche on Andesite Ridge.  We observed the avalanche from a low angle shoulder of the slide and were not able to see the whole slide path safely. Avalanche was at least 100' wide and potentially 50-100' downslope.  Slope angle was 46 degrees in the starting zone, on a NE aspect, at 7500', with a crown height approximately 1.5' deep.  This avalanche was consistent with other avalanche observations in this area today.

 

 

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