Regions
Kootenay Boundary.
Confidence
Fair - Timing, track, or intensity of incoming weather system is uncertain on Wednesday
Weather Forecast
Wednesday: Light snowfall intensifying overnight (up to 10cm) / Moderate to strong westerly winds / Freezing level at 1300mThursday: Continued flurries with possible sunny breaks / Moderate westerly winds / Freezing level at surfaceFriday: A mix of sun and cloud / Light northwest winds / Freezing level at surface
Avalanche Summary
Avalanche control on Monday produced numerous storm slabs to size 2 which occurred on a variety of aspects at treeline and in the alpine.
Snowpack Summary
Up to 40cm of recent storm snow was blown by variable strong winds into deeper deposits in lee terrain. These recent accumulations overlie crusts on previously sun-exposed slopes and surface hoar in shaded terrain. Rain at lower elevations has saturated the snowpack. Where the air temperature has dipped below freezing, lower elevation surfaces may exist as a refrozen crust.Below the new snow, 60-100cm of settled snow sits above buried surface hoar and crusts. The deeper facet/crust persistent weakness buried at the beginning of February, now down 70 to 160cm, has been highly variable in terms of reactivity but still shows 'sudden' results in snowpack tests. Needless to say, this interface is still very difficult to trust and any avalanche at these deeper, persistent interfaces would be large and destructive.Weak basal facets exist in many areas, but without a large load, triggering now is unlikely.
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.