Confidence
Good - Due to limited field observationsfor the entire period
Weather Forecast
Tuesday: Increasing clouds throughout the day, but no precipitation is expected until the evening. The freezing levels should drop to around 1900m as the temperature inversion weakens. Alpine winds are expected to remain light. Wednesday: Light flurries possible in the morning, then clearing throughout the day. Light northerly winds with freezing levels around 1200m. Clear, light wind , and freezing levels around 1900m.
Avalanche Summary
Avalanche activity has tapered off throughout the week. Although the likelihood of triggering avalanches is lower, the potential consequences are still very high.Likelihood of avalanches may increase on steeper, sun exposed slopes with forecast rising temperatures.
Snowpack Summary
Surface hoar is growing, surface snow is faceting, and pockets of weak wind slab may still be lingering on various aspects at and above treeline. Warm alpine temperatures and sun-exposure are creating wet surface snow in the afternoon, especially on south facing slopes, which is subsequently freezing into a crust overnight. Last weekends rain crust is down 20-40cm and extends up to treeline elevations. Basal depth hoar with an associated crust is prevalent in thin snowpack areas, and especially problematic where it is overlying summer firn. Above that, and down 1-2m, are two more crusts mixed with facets, depth hoar, and surface hoar. Time has allowed the overlying snow to gain strength making it less likely to trigger the deeper weaknesses, but if you do hit the sweet spot, such as a shallow area, the resulting avalanche could have very serious consequences.
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.