Buried surface hoar, facet, crust combo about 30cm down is the main concern found at treeline and subalpine locations particularly on NE aspects. This layer will persist.
Weather Forecast
Expect 5cm of snow Wednesday evening into Thursday. Flurries will continue until Saturday with sun and cold overnight temperatures after that. Temperatures trending colder next few days with light westerly winds.
Snowpack Summary
10cm overnight adds to the previous storm's 20cm snow overlying a surface hoar, surface facet and crust combo roughly 30cm down (Feb 10 layer), found predominantly at tree line and sub alpine elevations A hard mid-pack is providing bridging strength over the weak basal facet layer. Below tree line has a supportive yet shallow mid-pack.
Avalanche Summary
Patrols occurred in Maligne and Icefields Wednesday. Nothing noted in the Icefields. Skiers triggered a size 2 at Maligne area, 35m wide, 60m long, on a NE aspect 38 degree slope just above treeline on the Feb 10 surface hoar/facet layer. Stability tests showed moderate sudden planar/sudden collapse on this layer.
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.