Regions
Kootenay Boundary.
The new snowfall is very exciting, please remember to play safe and avoid avalanche terrain through times of dangerous avalanche conditions.
Weather Forecast
An intense system is moving across the interior ranges today bringing heavy precipitation amounts, rising freezing levels and strong ridgetop southerly-southwesterly winds. Freezing levels could rise to 1900m then fall to 800m before the next system passes. Thursday and Friday we should see freezing levels fall back to valley bottom and accompanied by steady light to moderate precipitation.
Avalanche Summary
Observations are extremely limited at this time. A few small size 1.0 avalanches were reported from the southern part of the region yesterday. The next few days will hold a different story. I'd expect widespread avalanche activity. They may react as storm slab instabilities with potentially triggering any weaknesses lower in the snowpack.
Snowpack Summary
Up to 40cm of new snow has fallen in the southern part of the region. This has been accompanied by moderate to strong winds from the southwest. In the alpine, and treeline new wind slabs are forming lee of ridgelines and terrain features. These wind slabs are sitting on older wind slabs and may have a poor bond. At treeline I suspect there to be some patchy areas of buried surface hoar and older raincrusts down 50-60cm. These may become reactive with the new storm snow load. Snowpack depths are likely in the 60-90cm range at about 1600m and about 150 cms at 2000m.
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.
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.