Numerous R4 D3 naturals, ~30hr old

Location Name: 
Job's Drainage
Region: 
Luther Pass Area (including Job and Freel)
Date and time of avalanche (best estimate if unknown): 
Sun, 02/20/2011 - 06:00
Location Map: 
United States
38° 52' 10.2648" N, 119° 51' 12.4488" W
See map: Google Maps
US


Red Flags: 
Recent avalanche activity
Recent loading by new snow, wind, or rain
Obvious avalanche path
Terrain Trap
Observation made by: Professional Observer
Avalanche Observations
Avalanche Type: 
dry,slab,loose,
Trigger type: 
Natural
Weak Layer: 
Storm Snow
Avalanche Width: 
200ft.
Terrain: 
Near Treeline
Bed Surface: 
Storm Snow
Avalanche Length: 
2 000ft.
Number of similar avalanches: 
5-10
More detailed information about the avalanche: 

Several recent large natural avalanches observed on both sides of NE facing drainage, with minimal new snow on deposition. Crowns and flanks were not obvious - most of these may have began as loose snow avalanches that entrained significant snow due to terrain constrictions. We were unable to assess snowpack at start zones, but similar aspects and slope angles in runout zones showed no signs of continued instabilities.

Avalanche Photos: 
Weather Observations
Blowing Snow: 
No
Air temperature: 
Below Freezing
Wind Speed: 
Calm
Precipitation: 
None
Air temperature trend: 
Static
Wind Direction: 
Accumulation rate: 
None
More detailed information about the weather: