Avalanches in Negro Canyon

Location Name: 
Negro Canyon
Region: 
Donner Summit Area
Date and time of avalanche (best estimate if unknown): 
Tue, 01/10/2017 - 11:30
Location Map: 
United States
39° 20' 40.578" N, 120° 17' 38.886" W
US


Red Flags: 
Recent avalanche activity
Whumphing noises, shooting cracks, or collapsing
Recent loading by new snow, wind, or rain

Observation made by: Forecaster
Avalanche Observations
Avalanche Type: 
Dry
Slab
Slope: 
40degrees
Trigger type: 
Natural
Aspect: 
East
Elevation: 
7 200ft.
More detailed information about the avalanche: 

Evidence of natural avalanche activity covered up by recent storm snow on steep wind loaded east aspects.  Visibility was very poor with strong to gale force SW winds along ridgeline.  On small test slopes below 7000', wind slabs were tender and failing easily up to 2' deep.  These wind slabs were failing about 4-6'' above the old snow rain crust within the recent storm snow.  Cornices were very large and built out along ridgelines.
 

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