Avalanche activity on Donner Summit

Location Name: 
Mt. Judah
Region: 
Donner Summit Area
Date and time of avalanche (best estimate if unknown): 
Fri, 12/03/2010 - 11:00
Location Map: 
United States
39° 18' 15.7248" N, 120° 19' 0.9048" 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
Observation made by: Professional Observer
Avalanche Observations
Avalanche Type: 
dry,slab,
Slope: 
35degrees
Trigger type: 
Natural
Crown Height: 
Less than 1 ft
Aspect: 
Northeast
Elevation: 
8 000ft.
Bed Surface: 
Storm Snow
More detailed information about the avalanche: 

Observations from Donner Summit/Mt. Judah area.  Thick high density new snow has fallen over yesterday into today making a dense wind affected upper snowpack.  Anywhere from 10-35cm of new snow depending on how much wind loading was occuring.  Very easy to kick off cornices and get slabs to propagate and run, all failures occuring within the lower new storm snow.  3 natural avalanches on the E side of Mt. Judah all looked to be triggered by cornice failure with crowns in the 30cm range.  2 ECTP-13 Q1 on E aspects, 35 degrees, 30cm slab depth.  Roller ball activity on all solar aspects below 7000'.  Total snow depth on Mt. Judah at 8100' 170cm.   

Photo: Natural cornice failure into small slab on Wildflower Ridge, N aspect, 7600'.

Video sound is challenging to hear due to wind.

Avalanche Photos: 
Avalanche observation video: 

judah2010-12-3 005.avi

judah2010 12 3 007

Weather Observations
Blowing Snow: 
Yes
Cloud Cover: 
100% of the sky covered by clouds
Air temperature: 
Below Freezing
Wind Speed: 
Moderate
Precipitation: 
Air temperature trend: 
Warming
Wind Direction: 
Southwest
Accumulation rate: 
None
More detailed information about the weather: