Windslab avalanches near Grouse Rock

Location Name: 
Grouse Rock
Region: 
Blackwood Canyon or Ward Canyon Area
Date and time of avalanche (best estimate if unknown): 
Sun, 11/27/2016 - 09:51
Location Map: 
United States
39° 8' 9.2832" N, 120° 14' 37.122" 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
Terrain Trap
Observation made by: Guide at Alpenglow Expeditions
Avalanche Observations
Avalanche Type: 
Slab
Slope: 
40degrees
Trigger type: 
Natural
Crown Height: 
3 ft
Aspect: 
Northeast
Weak Layer: 
Storm Snow
Avalanche Width: 
150ft.
Terrain: 
Near Treeline
Elevation: 
8 200ft.
Bed Surface: 
Old Snow
Avalanche Length: 
100ft.
Number of similar avalanches: 
2
More detailed information about the avalanche: 

Two windslab avalanches were observed on our tour today in Ward Canyon. Our best guess is they naturally released during the night due to strong windloading. The crowns ranged from roughly 1' to over 3'. Limited details as we only viewed these avalanches from a distance. 

Photo #1 shows both slides from the east. Smaller slide with approx 1' crown to the left, and much larger slide to the right with 3'+ crown.

Photo #2 again shows both slides, this time with crowns in profile. 

Aside from the overnight slab avalanches, we observed a good amount of new snow that was bonding well to the older snow underneath. Signs of instability were only found in the form of minor cracking and surface sluffing on the most obvious terrain features. Lots of evidence of wind, although the major windslab and stormslab instabilities apeared to have subsided as of midday in the area we traveled. 

Avalanche Photos: 
Weather Observations
Blowing Snow: 
Yes
Cloud Cover: 
75% of the sky covered by clouds
Air temperature: 
Below Freezing
Wind Speed: 
Light
Precipitation: 
None
Air temperature trend: 
Static
Wind Direction: 
North
Accumulation rate: 
None
More detailed information about the weather: 

No precip today, mostly clear skies in the morning changing to mostly cloudy by 1pm. Light wind and very nice skiing conditions. Solar radiation was moderate when the clouds parted.