It may continue to be possible to trigger a deep persistent slab avalanche in shallow snowpack areas.
Weather Forecast
Mostly cloudy overnight with a chance of flurries, light southwest winds and freezing at valley bottoms. Friday: Overcast with light winds and a couple of cm of new snow, and alpine temperatures -10. Saturday: Mix of sun and cloud with moderate westerly winds and warm air (possibly above freezing) moving into the alpine in the afternoon. Sunday: Mostly sunny with strong westerly winds and a pocket of warm air (possibly above freezing) in the alpine.
Avalanche Summary
No new avalanche reported. The main concern continues to be the possibility of triggering the weak faceted layers deeper in the snowpack.
Snowpack Summary
Up to 10 cm of low density snow sits above hard wind-affected surfaces. Below 1500 metres there may be an isolated thin breakable rain crust about 1 cm thick. In the Elk Valley north area near Crown Mountain on Tuesday the height of snow was 90 cm with foot penetration of 80 cm; or almost to ground. Some solar exposed terrain in the alpine may have a thin sun-crust about 3 cm thick, and this may have a few cm of light dry snow above . The snowpack is quite variable throughout the region. In deeper snowpack areas, the snowpack appears to be well settled with isolated concerns about the mid-December facet layer buried 50-100 cm deep. In shallow snowpack areas and lower elevations, the snowpack is weak and faceted. In these areas, winds have formed isolated hard slabs above weak facets and created the potential for large persistent slab avalanches.
Problems
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.