New windslabs may propagate further than expected on buried suncrust and surface hoar layers.
Weather Forecast
Thursday: Mainly cloudy with isolated flurries. Moderate west winds. Alpine high -7Friday: Cloudy with sunny periods and isolated flurries. Moderate west winds. Alpine high -7Saturday: Mainly cloudy with isolated flurries. Moderate southwest winds. Freezing level is uncertain with models predicting anywhere between 1500 and 2200m
Snowpack Summary
30cm of recently wind affected snow has gradually loaded either a suncrust below 2000m on solar aspects or spotty surface hoar in sheltered areas between 1600 and 1900m. This may be a problem layer when we see more snow. The midpack is strong in deep snowpack areas, but the facets lingering at the bottom remain a concern in thinner areas.
Avalanche Summary
Skier controlled wind slabs to 1 were reported in the Castle region yesterday.
Confidence
Freezing levels are uncertain on Saturday
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.
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.