Regions
Kootenay Boundary.
Watch for areas that have recently been affected by the wind. Wind slabs are expected to be lingering in leeward terrain features.
Confidence
Moderate - Wind speed and direction is uncertain
Weather Forecast
Sunny conditions are expected on Wednesday with treeline temperatures around -15C and light northeast wind in the alpine. Sunny conditions continue for Thursday and Friday with treeline temperatures around -12C during the afternoon and light to moderate alpine wind from the northwest.
Avalanche Summary
On Monday, two natural size 2 storm slabs were reported on southern aspects at 1850-2000m elevation. Explosives and ski cutting triggered several more storm slabs and wind slabs size 1-2.5. This activity was limited to the new storm snow sliding on the old snow surface. Slabs were typically around 15 cm thick and up to 30 cm thick in wind loaded areas. On Wednesday, recently formed wind slabs may still be reactive to human triggering. With the winds recently switching directions, wind slabs should be expected on a variety of aspects.
Snowpack Summary
10-20 cm of new snow has buried a highly variable old snow surface. This interface consists of wind scoured surfaces and old wind slabs in exposed terrain, widespread near surface faceting, surface hoar in sheltered terrain, and/or a breakable sun crust on steep solar aspects. Recent moderate winds from a variety of directions is expected to have redistributed some of this new snow in wind exposed terrain. In the upper snowpack below the new storm snow, a couple old freezing rain crusts from late-December may exist depending on your location. The mid-December surface hoar layer typically sits down 40-70 cm. This layer is still reactive to snowpack tests in some areas but is currently considered to be dormant or inactive. Below this layer, the snowpack is generally well settled and stable.
Problems
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.