The layer of facets, decomposing stellars and surface hoar down 40-70cms making it very difficult to predict the sensitivity of the persistent slab with field tests. Progressive decision from low angle to steep terrain is key for safe riding.
Weather Forecast
Light scattered flurries throughout the weekend, up to 6 to 8cm by Sunday evening. Temperatures to remain cool above treeline and freezing levels rising to 2000ms over the day Sunday. Winds expected to be in the lower moderate range from the Southwest.
Snowpack Summary
Continued building wind slab in lee and cross-loaded terrain above 2000m. A persistent weakness down 40-70cm is stubborn but can be triggered underfoot, especially in shallow areas. Snowpack is facetted at lower elevations and the base is extremely weak. Large triggers such as cornice fall or other avalanches will likely trigger this weakness.
Avalanche Summary
Field reports of solar triggered slab avalanches in the alpine and treeline in wind loaded areas up to size 3 in the Maligne area. Scoured areas, beside loaded features are obvious and we can't stress enough diligent decision making and general avoidance of these weaker and shallow areas .
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.