Regions
Banff Yoho Kootenay.
Current conditions are some of the most dangerous for backcountry travelers. Natural avalanches are unlikely; thus the problem is not obvious - but human triggered avalanches are likely, and happening daily. Keep a wide margin of safety . . .
Weather Forecast
Temperatures falling overnight to reach -15 by Wednesday with highs around -10. Possibility of up to 10 cm of new snow on Wednesday, but this looks to be in eastern areas only. Return to sunny skies for Thursday.
Snowpack Summary
25cm of recent storm snow has formed isolated soft slabs near ridge crests in the alpine. Persistent problems remain with facetting in the lower half of the snowpack. This is common to all areas and may be found at varying depths. Triggering is more likely in thin areas or near rocky outcrops.
Avalanche Summary
On Tuesday, skiers triggered a size 1.5 onto another group below in Lipalian 3 at Lake Louise. A large natural avalanche was reported on the North Face of Mt Temple today.
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.