Regions
Banff Yoho Kootenay.
A storm has brought new snow and moderate to strong winds to the area. It would be wise to let the snowpack adjust to this change as most inputs over last two months have induced avalanche cycles.
Weather Forecast
The current storm will have brought up to 10cm of new snow and rain below 1800m by the time it passes late Saturday. The moderate to strong west winds will back off into Sunday however trace amounts will continue to accumulate as temperatures cool. Clearing Monday will bring a cool morning and potentially some solar heating with very light winds.
Snowpack Summary
5 new plus 10 to 20 cm of recent snow sits over a firm 100 cm+ slab resting precariously over weak basal facets at all elevations. Tests show easy to moderate sudden collapse results in these facets. New surface snow sits on a mix of soft snow in the shade, sun crust on sun exposed slopes in the alpine, and melt-freeze or wet snow below treeline,
Avalanche Summary
The new snow combined with strong winds overnight has created some small touchy windslabs in alpine areas.
Problems
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.
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.