Natural and skier-triggered avalanches on Donner Peak

Location Name: 
Donner Peak
Region: 
Donner Summit Area
Date and time of avalanche (best estimate if unknown): 
Wed, 02/24/2010 - 09:00
Location Map: 
United States
39° 18' 43.668" N, 120° 18' 53.7696" W
See map: Google Maps
US


Red Flags: 
Recent avalanche activity
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: 
Natural
Crown Height: 
2 ft
Aspect: 
Northeast
Weak Layer: 
Other
Avalanche Width: 
600ft.
Terrain: 
Above Treeline
Elevation: 
7 400ft.
Bed Surface: 
Old Snow
Avalanche Length: 
800ft.
Number of similar avalanches: 
4
More detailed information about the avalanche: 

Several avalanches occured on steep terrain on Donner Peak. Some of these slides look to be natural releases and some may have been human-triggered. These avalanches most likely occurred on the morning of Feb. 24th. A motorist reported that the large natural avalanche on the NE face of Donner Peak occurred between when he went to work in the morning and when he came back down the hill at noon. The others likely occurred in a simmilar time period. Most of these slides showed evidence of stepping down onto older weak layers after starting in the new snow.

Snowpit or crown profile photo or graph: 
Avalanche Photos: 
Weather Observations
Air temperature: 
Precipitation: 
Air temperature trend: 
Wind Direction: 
Accumulation rate: 
More detailed information about the weather: