Small skier triggered avalanche below treeline on Hidden Peak

Location Name: 
Hidden Peak
Region: 
West Shore Area
Date and time of avalanche (best estimate if unknown): 
Sat, 03/26/2011 - 12:30
Location Map: 
United States
38° 58' 39.216" N, 120° 7' 21.4428" W
See map: Google Maps
US


Red Flags: 
Whumphing noises, shooting cracks, or collapsing
Recent loading by new snow, wind, or rain
Observation made by: Forecaster
Avalanche Observations
Avalanche Type: 
dry,slab,
Slope: 
41degrees
Trigger type: 
Skier
Crown Height: 
Less than 1 ft
Aspect: 
East
Weak Layer: 
Storm Snow
Avalanche Width: 
20ft.
Terrain: 
Below Treeline
Elevation: 
8 620ft.
Bed Surface: 
Old Snow
Avalanche Length: 
150ft.
More detailed information about the avalanche: 

New snow and wind with evidence of instability limited to the top 20 cm of the snowpack. Cracking in areas steeper than 32 degrees, slab failure observed only in areas steeper than 37 degrees

Photos 1 and 2: Intentionally skier triggered avalanche at noted lat/long with slope and terrain details listed above. This small avalanche was triggered by a hard check turn on the slope convexity where the crown formed. Slab thickness ranged from 10 to 15cm and appeared to be new snow from the last 12 hours. 4F hard slab over F+ hard bed surface. New snow today was higher density than new snow yesterday. Some light wind affect in this area, but no wind loading.

Photo 3: Shooting cracks were limited to wind slabs along the summit ridge. Slab failure occurred 20cm deep on a 4F+ wind slab over F+ storm snow.

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: 
Warming
Wind Direction: 
Southwest
Accumulation rate: 
Less than 1 in. per hour
More detailed information about the weather: