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 to moderate northerly wind in the alpine. Sunny conditions continue for Thursday and Friday with treeline temperatures remaining around -15C during the afternoon and light to moderate alpine wind from the northwest.
Avalanche Summary
An early report from Tuesday in the Invermere area includes a skier remotely triggering a size 1 wind slab from 10 m away on a northeast aspect at 2500 m elevation. This slab was in a loaded leeward terrain feature and was 25 cm thick. Explosives and ski cutting in the north of the region produced size 1-1.5 wind slabs. On Monday, reports include natural avalanches up to size 1.5 from steep, unskiable terrain.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
15-30 cm of new snow has buried a variable old snow surface which consisted of wind scoured surfaces or old wind slabs in exposed terrain, surface hoar in sheltered terrain, and/or widespread faceted old snow. Recent moderate winds from a variety of directions is expected to have redistributed some of this new snow in wind exposed terrain. The layer of facets from mid-December is still reactive to snowpack tests in isolated areas but is generally considered to be dormant during this period of cold, dry conditions. It will be important to watch this layer reacts during the next storm or period of warming.
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.