Forecast snowfall and wind on Sunday could build fresh and touchy wind slabs in exposed terrain. Choose your lines carefully and avoid exposure to terrain traps.
Weather Forecast
Sunday: Cloudy with light to moderate snow – 10-15 cm. The freezing level is around 1200-1400 m. Ridge winds are moderate from the S-SW. Monday: Cloudy with sunny breaks and a chance of flurries. The freezing level rises to 1000-1200 m during the day. Ridge winds are light. Tuesday: A mix of sun and cloud. The freezing level jumps up to 1500 m and winds remain light.
Avalanche Summary
Avalanche activity on Friday was limited to loose wet sluffs or pinwheeling on steep sun-exposed slopes, and isolated natural cornice failures. In some cases the cornice falls triggered small slabs below.
Snowpack Summary
New snow is probably sitting on surface hoar on sheltered and shady slopes, or a sun crust on sun-exposed slopes and lower elevation terrain. A couple sun crusts might exist in the top 30 cm on southerly aspects. New wind slabs will continue to develop on Sunday with forecast snowfall and moderate southwest winds in the alpine. The surface hoar and/or crust layer which was buried February 10 is now down 70-100cm but triggering this layer has become unlikely. Large cornices have recently been a concern but should also gain strength will colder temperatures.
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.