Test slope failures on Carson Pass near Frog Lake

Location Name: 
Frog Lake
Region: 
Carson Pass Area
Date and time of avalanche (best estimate if unknown): 
Tue, 01/26/2010 - 12:12
Location Map: 
United States
38° 41' 25.08" N, 119° 59' 24.828" W
See map: Google Maps
US


Red Flags: 
Recent avalanche activity
Recent loading by new snow, wind, or rain
Observation made by: Forecaster
Avalanche Observations
Avalanche Type: 
dry,slab,
Slope: 
40degrees
Trigger type: 
Skier
Crown Height: 
1 ft
Aspect: 
Northeast
Weak Layer: 
Storm Snow
Avalanche Width: 
20ft.
Terrain: 
Below Treeline
Elevation: 
8 650ft.
Bed Surface: 
Storm Snow
Avalanche Length: 
20ft.
Number of similar avalanches: 
3
More detailed information about the avalanche: 

Several test slopes released in response to the added weight of a skier in the Carson Pass area today. All of these slopes were wind-loaded and N-NE facing. They were all 37-40 degrees in steepness. The failure layer in all of these slides was a density change within the new snow. These test slopes failed in both near and below treeline terrain. I did no see any recent natural avalanche activity on other slopes in the area. Layer bonding tests showed weaknesses that broke with easy force at 2 density changes in the snow that had fallen since yesterday.

Photo 1: NE-Facing, 40 degree, wind-loaded test slope below treeline. Avalanche triggered by a skier. Slide ran 20 ft.

Photo 2: NE-Facing, 37 degree, wind-loaded test slope at treeline. Avalanche triggered by a car sized piece of cornice. Slide ran 60 ft.

Avalanche Photos: 
Avalanche observation video: 

Avalanche on a test slope near Carson Pass

Weather Observations
Blowing Snow: 
Yes
Air temperature: 
Below Freezing
Wind Speed: 
Moderate
Precipitation: 
Snow
Air temperature trend: 
Static
Wind Direction: 
Southwest
Accumulation rate: 
Less than 1 in. per hour
More detailed information about the weather: