Storm slabs are sensitive to human-triggering. Watch localized conditions - if overnight storm snow amounts are more than forecasted, danger levels could reach HIGH.
Confidence
Moderate - Forecast snowfall amounts are uncertain
Weather Forecast
Wednesday will bring moderate snowfalls with accumulations near 20cm. Alpine temperatures should reach -2 celsius with freezing levels near 1900m. Wind speeds will decrease overnight, but then return to the strong/extreme range on Wednesday afternoon.
Avalanche Summary
Nothing new was observed but visibility was very limited.
Snowpack Summary
Up to 15cm of new snow has fallen in the past 24hrs together with strong/extreme SW winds. This brings total snow overlying the Dec 4th layer to 20 to 40cm, and much more in lee features at ridge-top. The Dec 4th layer has developed into a critical weak layer. It consists of surface hoar crystals (some as large as 40mm) in sheltered areas below 2100m, sun crust on solar aspects, and facets in most other areas. This layer was reactive in field tests in the "easy" range today and forecasters observed cracking around their skis, all of which indicate a high likelihood of human triggering. Due to persistently strong SW winds over the past 48hrs, storm slab development has occurred in Alpine and Treeline areas on lee and cross-loaded features. The current and forecasted weather will lead to continued slab formation.
Problems
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.
Loose Dry
Loose Dry avalanches are the release of dry unconsolidated snow and typically occur within layers of soft snow near the surface of the snowpack. These avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs.