Sensitive wind slab at Carson Pass

Location Name: 
Meiss Ridge
Region: 
Carson Pass Area
Date and time of avalanche (best estimate if unknown): 
Fri, 12/24/2010 - 13:00
Location Map: 
United States
38° 42' 35.28" N, 120° 0' 29.88" 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: Professional Observer
Avalanche Observations
Avalanche Type: 
dry,slab,
Slope: 
40degrees
Trigger type: 
Other - explain below
Crown Height: 
1 ft
Aspect: 
North
Weak Layer: 
Old Snow
Avalanche Width: 
250ft.
Terrain: 
Above Treeline
Elevation: 
8 750ft.
Bed Surface: 
Old Snow
Avalanche Length: 
200ft.
Number of similar avalanches: 
1
More detailed information about the avalanche: 

I was on a 30 degree aspect, 25 degree slope angle, approaching a very recent R3 D2 debris pile (natural cornice drop) on a 0 degree aspect, 40 degree slope angle. I remotely triggered an additional R1 D2 adjacent to the natural path. Each slide ran the full length of the path, which is very short, ~200ft. Between these two, and a third older slide (debris visible far right of pic 1), the full width of the path failed.

pic 1: debris, both from the natural trigger and from my human trigger. Photo taken from my initial stance - note the propagation crack.

pic 2: stiff, supportable slab. Probing identified lower density layer, but no collapse, no hollow feel, etc.

pic 3: This very small slope failure on a 40 degree aspect was triggered remotely from ~30ft away. Similar weak layer - mostly DFbk with some small angular grains.

I tested other small windloaded features and got consistent results, but no additional remote triggers. Lower density DFbk and angular grains as all weak layers.

Snowpit or crown profile photo or graph: 
Avalanche Photos: 
Weather Observations
Blowing Snow: 
Yes
Air temperature: 
Below Freezing
Wind Speed: 
Strong
Precipitation: 
None
Air temperature trend: 
Static
Wind Direction: 
Southwest
Accumulation rate: 
None
More detailed information about the weather: 

Significant wind transport observed, both at my locations and visible from a distance all along the Sierra Crest from Echo to Mokelumne