Human-triggering of an avalanche in steep Alpine terrain is still possible. Evaluate the snowpack carefully before committing to a line.
Confidence
Moderate - Due to the number and quality of field observations
Weather Forecast
A mix of sun and cloud on Monday with no precipitation expected. Alpine temperatures should reach a high of -10 C and a temperature inversion is possible (cooler in the valleys). Ridge-top winds will be out of the west at 30 km/h. A weak system may bring light flurries to the region on Wednesday.
Avalanche Summary
Nothing new observed today, but a few avalanches up to size 1.5 (both loose dry and wind slabs) have occurred in the past 72hrs in steep Alpine terrain.
Snowpack Summary
Wind slabs are found in Alpine areas on all aspects due to persistent winds from variable directions. These slabs range between 5 and 25cm thick and are more concerning for human-triggering in shallow snowpack areas. Wind transport continues to move small amounts of snow around, which leaves a potential for some sluffing in steep terrain. Buried sun crusts are found on steep solar aspects, but so far this has not been an avalanche concern, but it is a ski quality concern. The Dec 4th layer is still found in the snowpack down 30 to 50cm, but this layer remains dormant at the moment. Shallow snowpack regions and lower elevations have seen significant faceting over the past 2 weeks leading to a progressively weaker snowpack in these areas.
Problems
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.
Loose Dry
Loose Dry avalanches are the release of dry unconsolidated snow and typically occur within layers of soft snow near the surface of the snowpack. These avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs.