Regions
Kootenay Boundary.
Cool temps and increased cloud cover should put the lid on solar activity on Sunday. Be aware that if the sun comes out, it could initiate cornice fall and natural slab failure surprisingly quickly.
Confidence
Fair - Timing or intensity of solar radiation is uncertain
Weather Forecast
Synopsis: The remnants of a very weak system pass over the region Saturday afternoon ahead of Sunday's strengthening ridge. A warm system approaches the coast Monday which should push high cloud into the region. There's potential for very high freezing levels on Tuesday, but it's still too far out to say. There's a chance for significant precipitation on Wednesday.Sunday: Freezing Level: 1000m - 1200m; Precipitation: Nil; Treeline Wind: Very light, Variable | Ridgetop Wind: Light, WestMonday: Freezing Level: 1000m; Precipitation: Nil; Treeline Wind: Light, NE | Ridgetop Wind: Light SWTuesday: Freezing Level: 1600m - 1900m; Precipitation: Nil; Treeline Wind: Light, SW | Ridgetop Wind: Light SW
Avalanche Summary
On Friday the strong sun heated the upper snowpack resulting in a natural cycle to size 2 on south and southeast facing slopes. Ski cuts on shady aspects produced avalanches to size 1.5. On Thursday a widespread natural avalanche cycle to size 2.5, averaging size 1.5 was reported. There were no reports of anything stepping down below the March 10th crust into the deeply buried persistent weak layers.
Snowpack Summary
20 - 40 cm of light density snow from last week rests on top approximately 30 cm of settled old storm snow. This makes for 50 - 70 cm on top of the March 10th crust. This crust is widespread to 2000m across the region, perhaps even higher on solar aspects. It's mostly supportable, we've received reports of it being as thick as 15cm in the south of the region, but it varies in thickness and supportability. As you head north in the region where the mountains are higher (and temperatures were colder when the crust was forming), this crust is less likely to exist.A facet/crust persistent weakness buried at the beginning of February, now down 70 to 200cm, has been highly variable in terms of reactivity but still shows 'sudden' results in some snowpack tests. In areas where the strong and supportive near surface crust exists, triggering this layer has become unlikely. That said, this layer is still difficult to trust and any avalanche at these deeper, persistent interfaces would be large and destructive.,
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.