Keep an eye on actual snowfall amounts on Wednesday. Strong winds and incoming snow has the potential to overload buried surface hoar and suncrusts.
Weather Forecast
Tuesday: Cloudy with scattered flurries. Snowfall amounts 4cm. Alpine high -10, strong SW winds.Wednesday: Periods of snow. There is disagreement on amounts in the models but we may see up to 15cm. Moderate W winds, freezing level 1300m.Thursday: Cloudy with isolated flurries. Freezing level down to valley bottom with moderate W winds.
Snowpack Summary
25cm of recently wind affected snow is sitting on either a suncrust below 2000m on solar aspects or spotty surface hoar in sheltered areas between 1600 and 1900m. This may be a problem layer as we see more snow this week. The midpack is strong in deep snowpack areas, but the facets lingering at the bottom remain a concern in thinner areas.
Avalanche Summary
A forecasting trip up the Akamina parkway revealed several small loose dry avalanches out of steep rocky terrain. A skier in the Fernie backcountry triggered an avalanche failing on the same surface hoar layer we are seeing in the park but was able to ski out of it. With up to 20cm of snow in the forecast we may see similar activity on this layer.
Confidence
Intensity of incoming weather systems is uncertain on Wednesday
Problems
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind 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.