Natural avalanches on Mt. Judah.

Location Name: 
Mt. Judah
Region: 
Donner Summit Area
Date and time of avalanche (best estimate if unknown): 
Tue, 11/23/2010 - 10:00
Location Map: 
United States
39° 18' 12.672" N, 120° 19' 2.388" W
See map: Google Maps
US


Red Flags: 
Recent avalanche activity
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: 
38degrees
Trigger type: 
Natural
Crown Height: 
3 ft
Aspect: 
East
Weak Layer: 
Storm Snow
Avalanche Width: 
100ft.
Terrain: 
Above Treeline
Elevation: 
8 200ft.
Bed Surface: 
Storm Snow
Avalanche Length: 
300ft.
Number of similar avalanches: 
3
More detailed information about the avalanche: 

These slides occured as rapidly formed wind slabs overloaded the existing snowpack this morning. They failed on the interface between the snow that fell on overnight on the 21st the snow that fell last night and this morning. This newly formed wind slabe is more stiff and dense than the snow underneath it creating and "upside-down" snowpack. These slides may have been trigger by natural cornice collapse. The remaining cornices were still sensitive to human-triggering and could be triggered several ft away from their edges.

Avalanche Photos: 
Weather Observations
Blowing Snow: 
Yes
Cloud Cover: 
50% of the sky covered by clouds
Air temperature: 
Below Freezing
Wind Speed: 
Strong
Precipitation: 
Snow
Air temperature trend: 
Cooling
Wind Direction: 
West
Accumulation rate: 
Less than 1 in. per hour
More detailed information about the weather: