Avalanche on Tallac

Location Name: 
Corkscrew slide path
Region: 
Desolation Wilderness Area (including Emerald Bay)
Date and time of avalanche (best estimate if unknown): 
Tue, 02/21/2017 - 01:00
Location Map: 
United States
38° 55' 15.7908" N, 120° 5' 11.8104" W
See map: Google Maps
US


Red Flags: 
Recent loading by new snow, wind, or rain
Obvious avalanche path
Observation made by: Professional Observer
Avalanche Observations
Avalanche Type: 
Wet
Slope: 
35degrees
Trigger type: 
Natural
Aspect: 
Northeast
Weak Layer: 
Other
Avalanche Width: 
150ft.
Terrain: 
Below Treeline
Elevation: 
6 800ft.
Bed Surface: 
Old Snow
Avalanche Length: 
1 000ft.
Number of similar avalanches: 
1
More detailed information about the avalanche: 

Large (D4) slide that appeared to run during the rain event on Monday 2/21/17. Approximately the bottom 500 feet were clearly visible under the new snow. The next few hundred feet became much faint and the top was impossible to discern under the new snow. 

Photo 1: Toe of the debris. Interesting to note that despite the large size of this slide, it only occupied a small portion of the historical slide path and deposition zone. 

Photo 2: Huge blocks in the debris. These were frozen solid and appeared to have been wet when they slid. 

Photo 3: Looking up from the tallest portion of the debris pile. Trees up to approximately 6 inches in diameter were visible within the debris. 

Photo 4: Looking down on the debris from higher on the side of the Corkscrew path. Above this vantage point the track and debris became much fainter and eventually wasn't visible at all. 

Avalanche Photos: 
Weather Observations
Air temperature: 
Precipitation: 
Air temperature trend: 
Wind Direction: 
Accumulation rate: 
More detailed information about the weather: