Natural avalanches and widespread cracking at Carson Pass

Location Name: 
Frog Lake Ridge
Region: 
Carson Pass Area
Date and time of avalanche (best estimate if unknown): 
Tue, 12/22/2015 - 09:00
Location Map: 
United States
38° 41' 32.532" N, 119° 59' 19.4964" 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
Slope: 
40degrees
Trigger type: 
Natural
Crown Height: 
3 ft
Aspect: 
East
Weak Layer: 
Old Snow
Avalanche Width: 
100ft.
Terrain: 
Near Treeline
Elevation: 
8 600ft.
Bed Surface: 
Old Snow
Avalanche Length: 
300ft.
Number of similar avalanches: 
2
Number of people caught: 
0
Number of partial burials: 
0
Number of full burials: 
0
More detailed information about the avalanche: 

2 adjacent natural avalanches observed along Frog Lake Ridge in windloaded, steep terrain. Too much hangfire for proper crown profiles, but adjacent safe slope showed 12/13 crust at about the same height (100cm from the surface) as crowns, with weak layer observed just below crust. Storm snow instabilities observed in this area were 20-30cm from the surface. Majority of steep terrain along Frog Lake Ridge had wall-to-wall deep cracking in start zones, but possibly too much compressive support for avalanches to occur.

Avalanche Photos: 
Weather Observations
Blowing Snow: 
Yes
Air temperature: 
Wind Speed: 
Strong
Precipitation: 
Air temperature trend: 
Wind Direction: 
Southwest
Accumulation rate: 
More detailed information about the weather: