A Special Public Avalanche Warning is in effect for this region. The only worthwhile riding is likely on the least trustworthy slopes. Be circumspect on large steep alpine slopes.
Weather Forecast
Saturday: Cloudy with possible light snow. The freezing level lowers to around 1500 m. Winds are generally light from the W-NW. Sunday: Mainly cloudy with light snow. The freezing level is around 1200-1500 m. Monday: A mix of sun and cloud, and mainly dry. Freezing levels in valley bottoms with light variable winds.
Avalanche Summary
Reports from Thursday include two cornice-triggered that stepped down to a deep persistent slab on a hanging face. A couple of explosive-triggered storm and and wind slabs up to Size 2 were also reported, but ski-cutting produced no results.
Snowpack Summary
Recent reports suggest 10-50 cm thick hard wind slabs lurk below ridge crests and behind terrain features at treeline and alpine elevations; however, these seem to be generally well-bonded. In more sheltered areas, variable amounts of previous storm snow is sitting on a crust that formed at the end of January. Recent warm temperatures have softened the upper snowpack, reawakening deep persistent weaknesses in isolated areas. As temperatures continue to fluctuate and stress the snowpack, expect an increased likelihood of triggering large destructive avalanches in isolated areas (e.g. thin spots) with heavy triggers (e.g. cornice falls, stuck sleds spinning tracks, or groups of people).
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.