The forecast calls for snow Friday night into Saturday, but not enough to shift avalanche danger dramatically
Confidence
Moderate - Forecast snowfall amounts are uncertain on Saturday
Weather Forecast
SATURDAY: Flurries Friday night into Saturday, accumulation 10-15cm / Moderate southwest wind / Alpine temperature -3 / Freezing level 1300mSUNDAY: Mix of sun and cloud with isolated flurries / Light west wind / Alpine temperature -5 / Freezing level 1100mMONDAY: Mix of sun and cloud / Light north wind / Alpine temperature -3 / Freezing level 1300m
Avalanche Summary
On Tuesday and Wednesday several explosive and skier controlled avalanches to size 2 and 2.5 were reported from a variety of aspects. These were mostly wind and storm slabs failing 10-40cm deep. Some were also triggered by cornices pulling out 20-40cm slabs on slopes below.
Snowpack Summary
A series of snowfalls over the early part of the week accumulated 30-60cm of storm snow that has been redistributed by predominantly southwest and southeast winds. 2000m and below, the storm snow lies above a crust that formed last week. All this sits above a melt freeze crust that was buried mid March . The mid-February crust/facet layer can still be found at the upper end of tree line and into the alpine. This layer is generally 120-170 cm deep but may be present nearer to the surface in wind scoured areas. Although there is growing confidence that this layer seems to be becoming dormant, a storm slab or cornice release in the right location may have the potential to trigger any of the deeply buried weak layers.
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.