Regions
Banff Yoho Kootenay.
Rain and warm temperatures continue to induce a large avalanche cycle. A cooling trend on Friday will be short lived, after which a second wave of weather will impact the forecast region.
Weather Forecast
Continued warm temps are expected tomorrow followed by a cooling trend on Friday. The wind is supposed to stay elevated in the strong range from the West. A second wave of precip is expected, yet again, on Saturday, accompanied by temperatures near zero.
Snowpack Summary
Additional snowfall and very warm temperatures have tipped the snowpack and an avalanche cycle is still underway. A 50 cm dense slab has overloaded two prominent weaknesses in the snowpack; one down 40cm and the other in facets near the base of the snowpack. Expect rain soaked snow at low elevation and a continued avalanche cycle.
Avalanche Summary
A major avalanche cycle is underway, avoid avalanche terrain.
Confidence
Timing, track, or intensity of incoming weather system is uncertain on Saturday
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.