Regions
Banff Yoho Kootenay.
Cooler temperatures forecasted for tomorrow should tighten up the snowpack. Watch for lingering windslabs in the alpine.
Weather Forecast
A mix of sun and cloud through Wednesday and Thursday. A cooling trend is forecasted with freezing levels to valley floors overnight, rising to 1500 meters during the day. Winds from the west in the moderate range.
Snowpack Summary
Very strong westerly winds have seriously blasted the region. Wind pressed snow and wind slabs in lee terrain can be expected in the alpine. On Tuesday the snowpack was isothermal below treeline in many areas, but we expect this condition to improve with forecasted cooler temperatures on Wednesday.
Avalanche Summary
The warm temperatures created a widespread avalanche cycle on Sunday and Monday. Tuesday saw slightly cooler temperatures and less natural activity. Avalanches observed were restricted to isothermal avalanches in shallow snowpack areas below treeline.
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.