Small natural avalanches near Grouse Rocks.

Location Name: 
Grouse Rocks
Region: 
Blackwood Canyon or Ward Canyon Area
Date and time of avalanche (best estimate if unknown): 
Sat, 02/28/2015 - 12:00
Location Map: 
United States
39° 8' 20.3748" N, 120° 14' 43.6092" 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: 
40degrees
Trigger type: 
Natural
Crown Height: 
Less than 1 ft
Aspect: 
Northeast
Weak Layer: 
Storm Snow
Avalanche Width: 
100ft.
Terrain: 
Above Treeline
Elevation: 
8 200ft.
Bed Surface: 
Storm Snow
Avalanche Length: 
200ft.
Number of similar avalanches: 
2
More detailed information about the avalanche: 

Multiple small natural avalanches observed in this area that appeared to have occurred mid day. Largest of the avalanches detailed above was a shallow wind slab that occurred just below the summit ridgeline at ~8,200' (photo 1). Second avalanche observed lower down on same aspect in large open area below treeline between 7,600' and 7,800' (photo 2). All avalanches appeared to have occurred on a subtle density difference within the storm snow. All crown heights were less than 30 cm with new snow amounts of 45 to 62 cm observed in the area.

Photos heavily contrasted due to low light conditions to make crown/flanks visible in the photos.

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