Avalanche on Castle Pk, N Aspect

Location Name: 
Castle Peak North Bowl
Region: 
Donner Summit Area
Date and time of avalanche (best estimate if unknown): 
Mon, 03/07/2011 - 08:37
Location Map: 
United States
39° 21' 53.1432" N, 120° 20' 44.2032" 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: Public
Avalanche Observations
Avalanche Type: 
dry,slab,
Slope: 
30degrees
Crown Height: 
Less than 1 ft
Aspect: 
Northeast
Weak Layer: 
Storm Snow
Avalanche Width: 
300ft.
Terrain: 
Near Treeline
Elevation: 
8 600ft.
Bed Surface: 
Old Snow
Avalanche Length: 
400ft.
More detailed information about the avalanche: 

Touring to Castle Pk from the top of the Frog Lake Cliffs, we observed strong wind transport onto the Frog Lake chutes plus cracking and collapsing in obvious, wind-loaded areas and returned into the teeth of the wind along the ridge towards Castle. We kicked a cornice into one of the north-facing chutes on Castle's north side and the snow just sloughed, but a small, <6" slab released from lower down the chute. The slab was on a NW aspect so had apparently been cross-loaded from the east. The large avalanche we noticed a moment later was 400' wide and started well below the ridgeline, apparently naturally, above a rocky area at about 30-35 degrees. The crown was approxiamately a foot high and the debris was deposited 400' down the slope. We decided to ski lower angle, S-facing slopes back to the car.

Avalanche Photos: 
Weather Observations
Blowing Snow: 
Yes
Cloud Cover: 
100% of the sky covered by clouds
Air temperature: 
Below Freezing
Wind Speed: 
Moderate
Precipitation: 
Snow
Air temperature trend: 
Static
Wind Direction: 
West
Accumulation rate: 
Less than 1 in. per hour
More detailed information about the weather: