Regions
Kootenay Boundary.
Check out the Tricky Holiday Conditions blog post for more details on the current avalanche scenario.
Confidence
Good - The weather pattern is stable
Weather Forecast
A dry arctic ridge will dominate the region for the forecast period. Skies will be mainly clear for the period with ridge top temperatures hovering at about -20, and moderate northeasterly winds.
Avalanche Summary
We continue to get reports of skier-triggered, and remotely triggered slab avalanches. Avalanche activity has mostly been in the size 2 range, failing on the mid-December layers. This pattern is expected to persist for the foreseeable future.
Snowpack Summary
Up to 25cm of low density snow fell over the last few days. This new snow, which overlies recently formed surface hoar, may have been shifted into fresh wind slabs in high elevation terrain. Up to 70 cm of snow from last week has consolidated into a slab above a touchy weak layer of surface hoar sitting on a thick rain crust. This widespread persistent layer continues to produce whumpfing and sudden snowpack tests, and will likely remain sensitive to human triggering for the foreseeable future. Although high elevation slopes may not have the rain crust, they are still reported to have touchy buried surface hoar. At the base of the snowpack, a crust/facet combo appears to have gone dormant for the time being.
Problems
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.
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.