Regions
Banff Yoho Kootenay.
New windslabs have formed in the alpine. Concern remains for the Dec 3rd persistent weak layer, dig frequently to check for presence of this spotty spotty surface hoar problem and keep a watchful eye on the character of the slab above it.
Weather Forecast
Westerly flow will bring light amounts of precip under mainly cloudy skies with light to moderate winds over the forecast period. Expect 10cm total through Monday as temps hover around -10C for daily highs at treeline. Winds should shift to a NW flow and bring some clearing beyond Monday after a system passes to the south of the forecast region
Snowpack Summary
Around 10cm of new snow now brings the faceted slab over the Dec 3 Surface Hoar to 30 to 50cm. While significant shears persist on this layer in isolated, shaded and sheltered areas from 1700m to 2150m, this problem has not been responsible for much activity and the potential for triggering is diminishing as the slab above it loses strength.
Avalanche Summary
A few reports of loose dry and windslab activity out of alpine terrain. Recent snowfall has combined with moderate W and SW winds creating isolated fresh slabs in alpine terrain.
Confidence
Due to the number of field observations
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.