Triggered slabs at Irwin

CBAC 2020-21 Observations

Date of Observation:
Name: Zach Guy


Zone: Northwest Mountains
Location: Irwin Tenure
Aspect: South East, West
Elevation: NTL


Avalanches: Intentionally ski triggered several fresh wind slabs (6” to 16”) thick, small in size (D1 to D1.5) on leeward and crossloaded features near treeline.
On west facing terrain, airblasts triggered 2 persistent slabs that broke into older snow layers, 12” to 18”, about D1.5 in size.
Weather: Light to moderate snowfall, moderate southwest winds.
Snowpack: 6” low density new snow was poorly bonded to previous wind hardened surfaces: shallow sluffing and easily triggered slabs in the new snow where winds were drifting it. Persistent slab structure is thin on windward aspects due to previous wind erosion.