Recent new snow and winds have formed slabs that sit on a weak layer. These slabs may be reactive to human triggering, especially in lee features at upper elevations.
Confidence
Moderate - The weather pattern is stable
Weather Forecast
SUNDAY NIGHT - Cloudy with clear periods / light northeast winds / alpine low temperature near -11 MONDAY - A mix of sun and cloud / light southwest winds / alpine high temperature near -10TUESDAY - A mix of sun and cloud / light southwest winds/ alpine high temperature near -8 WEDNESDAY - Cloudy with sunny periods / west winds, 10-30 km/h / alpine high temperature near -6
Avalanche Summary
On Saturday, a size 1 human triggered avalanche was reported on a northeast aspect around treeline. On Friday, a human triggered size 1 avalanche was reported on a northeast aspect at 1900 m. This avalanche reportedly occurred on the surface hoar layer that is buried 10-30 cm.
Snowpack Summary
The snow surface is likely a crust below approximately 1500 m, and on sun-exposed slopes at all elevations. Above 1500 m, the top 10-30 cm of snow is likely wind-affected. This 10-30 cm of recent snow is sitting on a weak layer of surface hoar (feathery crystals), which is most prominent around treeline. On sun-exposed slopes, the surface hoar may be sitting on a sun crust, and below treeline it may be sitting on a melt-freeze crust on all aspects.In shallow snowpack areas, the base of the snowpack is composed of facets (sugary snow). In deeper snowpack areas, the middle and lower portions of the snowpack appear to be generally strong.
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.