Regions
Kootenay Boundary.
Check out the Tricky Holiday Conditions blog post for more details on the current avalanche scenario.
Weather Forecast
The dry ridge of high pressure will persist bringing mainly clear skies for the entire forecast period. Ridgetop temperatures should hover around -20 for each day, while ridge top winds will be mainly moderate from the northwest.
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. With the current reverse loading pattern, I would expect a new round of wind slab activity on southeast through southwest facing terrain.
Snowpack Summary
Up to 35cm of low density snow fell over the last few days. This new snow, which overlies recently formed surface hoar, has likely been shifted by strong northerly winds into stiff and reactive wind slabs on south-facing terrain. Up to 90 cm below the surface, you'll likely find a touchy weak layer of surface hoar sitting on a thick rain crust. This buried snowpack structure was formed in mid-December and remains the primary layer of concern for the region. This widespread persistent weak 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.