Avalanche, near Lookout Pass

Location Name: 
Avalanche, FAA Towers ridge
Region: 
Silver Valley Area
Date and time of avalanche (best estimate if unknown): 
Mon, 01/31/2022 - 11:30
Location Map: 
United States
47° 27' 17.3016" N, 115° 40' 12.7956" W
US


Red Flags: 
Recent avalanche activity
Whumphing noises, shooting cracks, or collapsing
Recent loading by new snow, wind, or rain

Observation made by: Forecaster
Avalanche Observations
Avalanche Type: 
Dry
Slab
Slope: 
30degrees
Trigger type: 
Skier
Crown Height: 
Less than 1 ft
Aspect: 
Northeast
Weak Layer: 
Old Snow
Avalanche Width: 
50ft.
Terrain: 
Near Treeline
Elevation: 
6 000ft.
Bed Surface: 
Old Snow
Avalanche Length: 
200ft.
More detailed information about the avalanche: 

We remotely triggered this avalanche, intentionally, from a lower angle connected slope. A long shooting crack similar to the one pictured extended 30 feet in front of the skier to the area where the avalanche released. Slope angle in the start zone was generally 30 degrees and a slight convexity, but of note, the crown was slightly uphill of this convexity where the slope was less steep than 30 degrees. This was a NE facing slope just east of the towers area.

This relativley small soft slab avalache, SS-ASr-R3-D1.5-I, failed on the 1-2 cm layer of surface hoar visible in the crown photos. Despite it's size, it accelerated quickly and likely would have pushed a rider into the trees below at fairly high speed. The relatively low slope angle and remotely triggered nature of this avalanche illustrate how well a fracture can propagate on a weak layer of large surface hoar.

Avalanche Photos: 
Weather Observations
Blowing Snow: 
No
Cloud Cover: 
75% of the sky covered by clouds
Air temperature: 
Below Freezing
Wind Speed: 
Light
Precipitation: 
Snow
Air temperature trend: 
Cooling
Wind Direction: 
West
Accumulation rate: 
Less than 1 in. per hour