Regions
Kootenay Boundary.
The slopes with the best riding conditions are also the most dangerous - steep alpine slopes
Confidence
Low - Due to the number of field observations
Weather Forecast
Friday: Mainly cloudy with light snow flurries bringing up to 5 cm of snow. Freezing levels in valley bottoms and light southerly ridgetop winds. Saturday: Increasing snowfall with 10-15cm possible by Sunday morning. Freezing levels in valley bottoms and light southwesterly becoming moderate to strong southerly ridgetop winds. Sunday: Another 5-10cm possible with freezing levels peaking at 1400m and moderate southerly easing to light southwesterly ridgetop winds.
Avalanche Summary
Reports from Wednesday include numerous natural and skier-controlled 20-90cm thick storm slab avalanches up to Size 2 primarily on east through northeast aspects as low as 1600 m.
Snowpack Summary
Recent heavy rain to treeline elevations and wet snow above saturated and loaded the upper snowpack, forming a thick crust which now has up to 20cm fresh snow on top (with perhaps a thin crust within it). Weaknesses linger within the recent snow as well as at deeper old snow surface interfaces, which consists of facets, surface hoar, and/or a crust at upper elevations (especially on southerly aspects). The most critical of these is surface hoar buried early December (now likely down 50-100cm), which has the potential for remote triggering, extensive releases and prolonged sensitivity to triggers. It is likely lurking in most sheltered areas treeline and below. The thick mid-November crust is just under this weakness.
Problems
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.