Avalanche activity near and above treeline on Silver Peak

Location Name: 
Silver Peak
Region: 
Cabin Creek, Deep Creek, or Pole Creek Area
Date and time of avalanche (best estimate if unknown): 
Sat, 03/13/2010 - 00:30
Location Map: 
United States
39° 13' 22.8396" N, 120° 14' 47.6268" W
See map: Google Maps
US


Red Flags: 
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: 
1 ft
Aspect: 
Northeast
Weak Layer: 
Storm Snow
Avalanche Width: 
100ft.
Terrain: 
Near Treeline
Elevation: 
8 200ft.
Bed Surface: 
Old Snow
Avalanche Length: 
600ft.
Number of similar avalanches: 
5-10
More detailed information about the avalanche: 

While touring in the Silver Peak area, we observed several avalanches that most likely occurred during the storm on Friday night. They were all on 35-40 degree wind-loaded NW-N-NE aspects near and above treeline. Snowpit data from the crown of one of these slides showed the failure layer to be the interface between Friday night's snow and the old snow below. A small graupel layer was sometimes present at this interface. ECT tests performed on the crown at one of these slides showed mostly stable snow (ECTN Q2 @ 17 taps 26 cm down). The crowns and debris had new snow on top of them indicated that these slides occurred before the end of the storm on Saturday morning.

Photo 1: Avalanche on a NW facing, near treeline, 38 degree slope. Cornice collapsed after the slide occurred.

Photo 2: Same slide from above. Note the fresh cornice debris and the buried crown.

Photo 3: 3 more simmilar natural avalanches on N and NE facing slopes west of Silver Peak.

Photo 4: Crown and buried debris from another natural slide on a N facing slope with a 38 degree starting zone.

Avalanche Photos: 
Weather Observations
Cloud Cover: 
Clear
Air temperature: 
Above Freezing
Wind Speed: 
Calm
Precipitation: 
Air temperature trend: 
Warming
Wind Direction: 
Accumulation rate: 
More detailed information about the weather: