Regions
Banff Yoho Kootenay.
Excellent ski conditions out there right now! Forecasters still have some uncertainty in the danger rating due to the spatial variability of the Dec. 3rd surface hoar layer. This is an unusual situation where the danger is highest below treeline
Weather Forecast
We are under the influence of a ridge of high pressure for the next few days. Expect to see clearing skies through the week, minimal snow and light NW winds. Temperatures will remain cool in the -10 to -20 range. No inputs to significantly change the danger rating or ski conditions are expected.
Snowpack Summary
In sheltered terrain between 1700 and 2150m, a 30-40 cm soft slab sits over the December 3rd surface hoar. This layer continues to produce whumphs and easy shears in many locations, especially in areas to the West with more snow. No other significant shears have been observed. In the alpine isolated wind slabs exist in immediate lee areas.
Avalanche Summary
Sunshine ski area avalanche control team reported triggering small soft windslabs in steep alpine terrain with explosives today. Otherwise no new avalanches observed.
Problems
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.
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.