Regions
Kootenay Boundary.
The recent snows fell on a variety of firm, old surfaces. Expect sluffs and loose dry avalanches to run fast and far.Avalanches could grow quickly as they entrain snow through the track.
Confidence
Fair - Wind speed and direction is uncertain on Friday
Weather Forecast
Synopsis: An approaching arctic airmass will bring dry cold conditions throughout the forecast periodFriday: Sunny with cloudy periods / Winds: light to moderate from the northwest / Freezing level: 500m.Saturday: Sunny with cloudy periods / Winds: light from the northwest / Freezing level: Valley bottom.Sunday: Sunny with cloudy periods / Winds: light from the northwest / Freezing level: Valley bottom.
Avalanche Summary
We've been receiving occasional reports of avalanche activity occurring on week layers close to the ground suggesting they haven't gone away yet. However, as the temperatures drop and tighten up the snowpack triggering these layer will become increasingly difficult.
Snowpack Summary
Up to 20cm of snow now overlies a variety of old surfaces including stubborn wind slabs in exposed upper elevation terrain, well developed surface hoar in sheltered terrain and a crust on south aspects.The recent prolonged warm temperatures formed a strong and supportive midpack. Closer to the ground, the two weak layers we've been worried about thus far this season (the late November surface hoar, and a crust/facet combo from October) are still there. While the increased strength of the overlying slab has made these layers have become increasingly unlikely to trigger, large and destructive avalanches are still possible with the right input such as a cornice fall or a heavy load over a thin spot in steep terrain.
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.