Touchy conditions continue. Very cautious route-selection is advised as human-triggering is a very real possibility. Also, keep an eye out for solar-triggering as the air temps are warm and the solar radiation is significant.
Weather Forecast
A ridge of high pressure has pushed into the region and will bring generally clear skies. Winds will be moderate to strong from the West. Alpine temperatures will climb to near +1 C, with freezing levels reaching 2000m. Tuesday and Wednesday will be a bit warmer before a slight cooling trend on Thursday.
Avalanche Summary
A group of skiers remotely triggered a size 2.0 avalanche near Black Prince today on an East aspect at 2200m. The slab was approximately 80cm deep and failed in the basal weak layers. There was nobody buried. In addition, a natural avalanche cycle continued today with avalanche activity up to size 3.0 in lee and cross-loaded terrain. A few of these avalanches initiated in the upper snowpack and then steeped down to the Dec 18th persistent weak layer once they reached the Treeline elevation band.
Snowpack Summary
Wind slabs dominate the Alpine and Treeline elevation bands. These slabs are found on all aspects, but the most recent loading pattern is from the SW loading up traditional lee and cross-loaded terrain and starting to strip windward slopes in the Alpine. As can be expected, the wind has helped the cornices grow and in some cases these have fallen off and started avalanches within the recent wind slabs. Below Treeline still has a distinct "upside down" feel to it due to the weak mid-pack. Whumphing is widespread and can propagate a long ways through the weaker layers. Think of this as you approach overhead terrain.
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.
Cornices
Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.
Deep Persistent Slabs
Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.