Regions
Banff Yoho Kootenay.
Conditions are extremely variable from west to east. The Yoho side of the forecast region has 15 cm of recent powder snow on the surface, while the Lake Louise side of the region is a windswept barren. Tonight's cold front should deposit 5-15 cm.
Weather Forecast
The passing cold front tonight will bring 5-15cm of snow accompanied by NW winds and cooling temperatures. Saturday and Sunday will bring flurries with continued moderate NW winds and moderate temperatures.
Snowpack Summary
10-15cm of recent snow has fallen west of the divide. This sits on a supportive but weak mid-pack over weak basal facets. On the East side of the divide strong West winds have stripped all windward slopes. Lee and cross loaded gullies have a mix of hard and soft wind slabs over a weak shallow base.
Avalanche Summary
A size 2 explosive triggered avalanche on a NE alpine feature at Lake Louise slide on the ground. A few natural loose snow avalanches up to size 2 out of very steep rocky alpine terrain were also observed in the Emerald Lake area.
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.