Wind-slabs on test slopes 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): 
Tue, 02/23/2010 - 15:14
Location Map: 
United States
39° 18' 46.6236" N, 119° 54' 18.9252" 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: 
35degrees
Trigger type: 
Skier
Crown Height: 
Less than 1 ft
Aspect: 
Northeast
Weak Layer: 
Storm Snow
Avalanche Width: 
40ft.
Terrain: 
Above Treeline
Elevation: 
9 200ft.
Bed Surface: 
Storm Snow
Avalanche Length: 
30ft.
Number of similar avalanches: 
3
More detailed information about the avalanche: 

Continuous wind transport by SW wind this afternoon. Wind-slabs 4-8 inches deep formed on wind-loaded slopes near and above treeline. These slabs are sitting on a mix of unconsolidated recent snow, old crusts, and old snow. Several test slopes failed in response to a skier's weight in this area. The weak layer in most cases was a layer of graupel at the base of the newly-formed wind-slabs. Several shooting cracks also occurred on wind loaded slopes. These wind slabs only existed near the ridgelines and did not extend very far down slope. As we get more snow and wind I expect these slabs to increase in size and distribution and become more active.

Photo 1: Skier triggered wind-slab on a NE-facing, 37 degree test slope. Crown is about 40 ft wide and 4-8 inches deep.

Photo 2: Wind slab blocks showing thickness of the slab as of 3pm Tues.

 

Snowpit or crown profile photo or graph: 
Avalanche Photos: 
Avalanche observation video: 

Rose2 23 003

Shooting cracks on the far east ridge of Tamarack Peak - Mt. Rose area

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: 
Cooling
Wind Direction: 
Southwest
Accumulation rate: 
Less than 1 in. per hour
More detailed information about the weather: