Test slope failure and shooting cracks near treeline on the Far East Ridge of Tamarack Peak

Location Name: 
Far East Ridge of Tamarack Peak
Region: 
Mount Rose Area
Date and time of avalanche (best estimate if unknown): 
Fri, 04/02/2010 - 11:15
Location Map: 
United States
39° 18' 46.98" N, 119° 54' 19.2348" W
See map: Google Maps
US


Red Flags: 
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,
Slope: 
40degrees
Trigger type: 
Skier
Crown Height: 
Less than 1 ft
Aspect: 
Northeast
Weak Layer: 
Storm Snow
Avalanche Width: 
100ft.
Terrain: 
Near Treeline
Elevation: 
9 100ft.
Bed Surface: 
Storm Snow
Avalanche Length: 
30ft.
Number of similar avalanches: 
4
More detailed information about the avalanche: 

The southwest winds over the last 24 hours have formed shallow but fragile wind slabs on the wind-loaded, N-NE aspects in the Mt Rose backcountry. These slabs ranged from 4-12 inches thick and only existed near and above treeline. These slabs could be triggered by stepping onto the wind slabs with one ski. They could also be triggered from lower angle slopes. All of the slides occurred on N-NE facing 38-44 degree, wind-loaded slopes near and above treeline. Some of these slides were triggered from up to 15-20 ft away. The newly formed wind slabs (4f hardness) served as the slab layers. The bed surface was the softer snow from the night of March 30th (still F hardness). The weak layer was the interface between these two layers. In non-wind-affected areas, the snow remained soft and light on the northerly aspects and no signs of instability were observed.

Photo: Shooting crack in lower angle wind  loaded terrain near treeline.

Video: Remotely triggered avalanche on a NE facing, wind-loaded test slope.

Avalanche Photos: 
Avalanche observation video: 

Remotely triggered avalanche on a test slope in the Mt. Rose Backcountry - Tahoe area

Weather Observations
Blowing Snow: 
Yes
Air temperature: 
Below 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: