Avalanche in Old Ski Bowl

Location Name: 
Avalanche in Old Ski Bowl
Region: 
Mt. Shasta
Date and time of avalanche (best estimate if unknown): 
Sat, 03/25/2017 - 12:30pm
Location Map: 
United States
41° 21' 58.6224" N, 122° 12' 23.1012" W
US


Red Flags: 
Recent loading by new snow, wind, or rain
Rapid warming

Observation made by: Forecaster
Avalanche Observations
Avalanche Type: 
Wet
Slab
Slope: 
38degrees
Trigger type: 
Snowmobiler
Crown Height: 
Less than 1 ft
Aspect: 
East
Weak Layer: 
Storm Snow
Avalanche Width: 
75ft.
Terrain: 
Near Treeline
Elevation: 
8 000ft.
Bed Surface: 
Storm Snow
Avalanche Length: 
250ft.
Number of people caught: 
0
Number of partial burials: 
0
Number of full burials: 
0
More detailed information about the avalanche: 

I came across this avalanche just after it happened. This easterly aspect of Green Butte, off the shoulder of Powder Bowl, is a frequent flyer for all types of avalanches. Yesterday we noted wet storm slabs as possible and this is exactly what occurred. Our upside down snowpack layering, with heavy wet snow on top of lighter density snow, was the cause for this human triggered avalanche early in the afternoon. The top, wet layers of the new snow "greased" off and slid within the lighter density snow layers above the old snow surface. Nobody was caught or injured.

Also included in pictures was a day or two old wind slab avalanche off north aspect of Green Butte.

Avalanche Photos: 
Weather Observations
Blowing Snow: 
No
Cloud Cover: 
25% of the sky covered by clouds
Air temperature: 
Below Freezing
Wind Speed: 
Calm
Precipitation: 
None
Air temperature trend: 
Static
Wind Direction: 
Southwest
Accumulation rate: 
None
More detailed information about the weather: 

Clear, low level clouds, full sun for most of the day. Winds were light. This aspect is sheltered and gets full sun for a good portion of the day.