Natural cornice collapse triggers loose wet avalanche on Donner Peak.

Location Name: 
Donner Peak
Region: 
Donner Summit Area
Date and time of avalanche (best estimate if unknown): 
Wed, 03/15/2017 - 11:47
Location Map: 
United States
39° 18' 44.3232" N, 120° 18' 53.352" W
See map: Google Maps
US


Red Flags: 
Rapid warming
Obvious avalanche path
Observation made by: Forecaster
Avalanche Observations
Avalanche Type: 
Wet
Loose/Point-Release
Trigger type: 
Natural Cornice Collapse
Aspect: 
Northeast
Weak Layer: 
Old Snow
Avalanche Width: 
40ft.
Terrain: 
Above Treeline
Elevation: 
7 400ft.
Bed Surface: 
Old Snow
Avalanche Length: 
700ft.
More detailed information about the avalanche: 

Witnessed a large cornice collapse (30 to 40 foot wide section) that triggered a loose wet avalanche on the slope below on the NE aspect of Donner Peak today. This was a very large trigger on the slope below. This avalanche was size D2. Signs of other numerous large cornice collapses from recent days existed on surrounding peaks but without associated loose wet avalanches larger than size D1.

Avalanche Photos: 
Weather Observations
Blowing Snow: 
No
Cloud Cover: 
25% of the sky covered by clouds
Air temperature: 
Above Freezing
Wind Speed: 
Moderate
Air temperature trend: 
Warming
Wind Direction: 
Southwest