Natural Wind Slab Avalanches on Mt. Judah

Location Name: 
Mt. Judah
Region: 
Donner Summit Area
Date and time of avalanche (best estimate if unknown): 
Sat, 03/31/2012 - 12:00
Location Map: 
United States
39° 18' 9.5976" N, 120° 19' 2.0352" 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
Observation made by: Forecaster
Avalanche Observations
Avalanche Type: 
dry,slab,
Slope: 
38degrees
Trigger type: 
Natural
Crown Height: 
2 ft
Aspect: 
East
Weak Layer: 
Storm Snow
Avalanche Width: 
100ft.
Terrain: 
Above Treeline
Elevation: 
8 200ft.
Bed Surface: 
Old Snow
Avalanche Length: 
500ft.
Number of similar avalanches: 
5
More detailed information about the avalanche: 

Several natural wind slab avalanches had occurred along the summit ridge line of Mt. Judah. All of these slides were 1-2 ft deep and slide on either the rain crust at the base of the new snow or a density change about 10-20 cm above that. All of these slides likely occurred yesterday evening and had been covered by 6-10 inches of new snow overnight. ECT tests adjacent to the one of the crowns showed some unstable results and some stable results on the interface between the rain crust and the new snow and on density changes in the new snow. This snowpit was performed today on April 1.

 

Snowpit or crown profile photo or graph: 
Avalanche Photos: 
Weather Observations
Blowing Snow: 
No
Cloud Cover: 
25% of the sky covered by clouds
Air temperature: 
Above Freezing
Wind Speed: 
Calm
Precipitation: 
Air temperature trend: 
Warming
Wind Direction: 
Accumulation rate: 
More detailed information about the weather: 

Mostly sunny skies and temperatures in the 40s on Judah caused significant warming. Sun exposed slopes started ot become sticky and wet by noon on April 1.