A weak layer of surface hoar exists primarily at lower elevations. Be suspicious of steep features such as open glades and gullies.
Confidence
Moderate - The weather pattern is stable
Weather Forecast
TUESDAY NIGHT - Clear periods / southwest winds, 15-30 km/h / alpine low temperature near -7WEDNESDAY - A mix of sun and cloud / west winds 20-40 km/h / alpine high temperature near -6THURSDAY - A mix of sun and cloud with isolated flurries / southwest winds 20-30 km/h / alpine high temperature near -5 / freezing level 1500 mFRIDAY - Cloudy with scattered flurries, up to 5 cm / southwest winds, 20-30 km/h / alpine high temperature near -3
Avalanche Summary
No new avalanches were reported on Saturday or Sunday.
Snowpack Summary
10-30 cm of recent snow overlies a weak layer of sun crusts on south facing slopes, and surface hoar (feathery crystals) in sheltered areas. The surface hoar is most prominent at treeline and below. Previous strong winds had formed wind slabs over this weak layer. These may to be susceptible to human triggers.Large variability in snow depths still exists in the region, ranging from almost no snow to nearly 200 cm in some areas. For average snowpack areas, expect to find weak and sugary faceted snow around 50 to 100 cm deep, which extend to the ground. This weak bottom half of the snowpack was the culprit in several large avalanches in the region in the past few weeks.
Problems
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.
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.