Regions
Northwest Inland.
In the come-down after the storm, watch for wind slabs in all exposed terrain and the potential for triggering deeper layers on unsupported (convex) terrain features.
Confidence
Low - Due to the number of field observations
Weather Forecast
Thursday: Cloudy but mostly dry. Winds diminishing to around 30 km/h from the northwest. Alpine temperatures around -7C.Friday: Dry with some sunny breaks. Winds light southeasterly. Alpine temperatures around -12C.Saturday: Dry and sunny. Winds light northeasterly. Alpine temperatures around -20C.
Avalanche Summary
Storm slab avalanches were reported from the region on Wednesday with few details, and we previously had reports of two small avalanches on north facing terrain on Sunday.
Snowpack Summary
Up to 60 cm new storm snow now sits over a highly variable interface comprising of wind-scoured surfaces, hard wind slabs, faceted (sugary) snow, and maybe some feathery surface hoar in sheltered areas. The new snow is expected to bond poorly to this interface, but observations to confirm this are hard to come by. The winds have been cranking, and the new snow has been blowing into wind slabs behind exposed terrain features. The snowpack is still shallow throughout the region and widespread faceting of the entire snowpack is likely in most areas. A thick rain crust that formed in early November is probably near the bottom of the snowpack and is probably surrounded by sugary facets. Reports from the Ningunsaw Pass area and the far north of the region suggest that depth hoar is developing in shallow snowpack areas.
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.
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.