Quick report
- Slope Angle
- 40°
Avalanche
- Slab Width
- 91 m
- Weak Layer
- Facets
- Trigger Type
- Skier
- Vertical Fall
- 76 m
- Avalanche Type
- Hard Slab
- Slab Thickness
- 61 cm
- Trigger Detail
- Remotely Triggered
- Start Zone Aspect
- West
- Avalanche Problem
- Persistent Weak Layer
- Start Zone Elevation
- 3292 m
This avalanche occurred at the Alta Ski Area on a slope that did not have any previous ski tracks or explosive work. It represents a backcountry snowpack.
Two ski patrollers were approaching this slope because it is a common slope that gets loaded by south winds. As they approached the slope, they triggered a collapse and remotely triggered it. Red circle shows them after the avalanche released near the trigger point.
Remotely triggered avalanches like this are a major red flag.
Photos courtesy of Alta Ski Patrol who also provided a photo of the same slope on Jan 2 just before light snow on Jan 4 capped the faceted December snowpack and preserved the weak layer on the surface.
Photo below from Jan 2
Photo from the avalanche crown showing weak layers in the snowpack. The line in the middle is a fist hard layer of facets that much of the avalanche failed on. Below that weak layer are much harder layers of facets (about 1 finger hardness) with very weak, depth hoar at the ground. Large parts of the avalanche broke on that depth hoar around rocks seen in the Jan 2 photo as well as photos of the bed surface.