Loose Wet Snow Avalanches Above Black Wall

Location Name: 
Above Black Wall
Region: 
Donner Summit Area
Date and time of avalanche (best estimate if unknown): 
Sun, 03/27/2016 - 11:00
Location Map: 
United States
39° 19' 39.036" N, 120° 19' 4.6488" W
See map: Google Maps
US


Red Flags: 
Recent avalanche activity
Rapid warming
Obvious avalanche path
Observation made by: Public
Avalanche Observations
Avalanche Type: 
Wet
Loose/Point-Release
Slope: 
40degrees
Trigger type: 
Natural
Crown Height: 
Less than 1 ft
Aspect: 
Northeast
Weak Layer: 
Other
Avalanche Width: 
50ft.
Terrain: 
Below Treeline
Elevation: 
7 000ft.
Bed Surface: 
Other - explain below
Avalanche Length: 
100ft.
Number of similar avalanches: 
4
More detailed information about the avalanche: 

Little to no evidince of an overnight refreeze in the Donner Summit area around Black Wall today. Deep wet snow existed on all aspects by 10 am up to at least 7400 ft. Some E-SE-S aspects above 7000 ft. were barely skier supportable until 11:30. Ski cuts and kicks on N-NE-E-SE-S facing test slopes steeper than 37 degrees would trigger loose wet point releases (sluffs), pinwheels up to 1.5 m in diameter, or roller balls. Some natural loose wet point releases also occured on NE-E aspects at the coordinates attached to this observation around 11:00 am. Other recent loose wet sluffs that likely released in the last 24 hours also existed on nearby slopes.

Photos 1 & 2: The largest of the loose wet point release avalanches noted today. NE-E aspect, 7000-7100 ft., 38 to 42 degree slope. 

Photo 3:  One of the smaller point releases that occurred today at 11:00 on an ENE aspect close to the slope described above.

Photo 4: Large pinwheels on a N aspect test slope at 7100 ft. 

Video: Skier triggered loose wet snow sluff on a N facing test slope at 7100 ft. 

Avalanche Photos: 
Avalanche observation video: 

Loose Wet Sluff Above Black Wall on Donner Summit

Weather Observations
Blowing Snow: 
No
Cloud Cover: 
50% of the sky covered by clouds
Air temperature: 
Above Freezing
Wind Speed: 
Light
Precipitation: 
Rain
Air temperature trend: 
Static
Wind Direction: 
Southwest
Accumulation rate: 
Less than 1 in. per hour
More detailed information about the weather: 

Periods of sun mixed with light rain through out the morning.