Regions
Kootenay Boundary.
Fresh storm slabs are sitting above a layer of surface hoar. For more details on how to manage these avalanche conditions check out the recent forecaster blog post.
Confidence
Fair - Due to the number of field observations
Weather Forecast
A weak ridge of high pressure will begin to build across southern British Columbia on Monday. Scattered flurries with light precipitation amounts are expected. The ridge will strengthen Tuesday. The next system is forecast to hit the north Coast on Wednesday although models are in disagreement about whether it will be able to displace the ridge and slide down into the southern interior. Temperatures will remain mild through the period with light westerly winds.
Avalanche Summary
Reports indicate that Sunday saw touchy avalanche conditions with the storm slabs reacting to ski cuts and explosive control. Expect this trend to continue. Avalanche reports from earlier in the week described large avalanches releasing on persistent weak layers deep in the snowpack. Unfortunately the recent snowfall was not as great as anticipated the the storm didn't test the deeper week layers as much as we had hoped meaning it is going to stay on our radar for a little longer
Snowpack Summary
The recent snow and wind added a moderate load to a layer of surface hoar and or facets that was buried earlier in the week and can now be found down 20-40cm. In many places these week crystals sit above a thin crust that can be found up to about 1900m on north aspects and all the way to ridgeline on south aspects. A deeper crust/surface hoar combo buried in mid-December continues to be a concern. This layer can be found between 70 and 130cm down. While it is deeper and less likely to be triggered by people, step down avalanche are possible. Near the base of the snowpack the facet/crust combo formed in November appears to be dormant for the time being.
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.
Deep Persistent Slabs
Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.