Weather forecasts are calling for 40cm of new snow and extreme winds over the next 36hrs. This new snow loading will overload the Jan 6 weak layer and likely produce a significant natural avalanche cycle. Conservative terrain choices are recommended.
Confidence
Fair - Timing, track, or intensity of incoming weather is uncertain
Weather Forecast
Up to 40cm of new snow is expected Tuesday night and Wednesday. winds will switch to the SW and remain in the extreme range (hitting 100km/h). Temperatures near -8 for a high on Wednesday.
Avalanche Summary
Few naturally triggered loose dry slides up to size 1.5 occurred at treeline and above on steep terrain on all aspects. One naturally triggered slab failed on a steep slope of Mt Nestor at 2700m on a S asp.
Snowpack Summary
5cm of new snow with up to 25cm of recent storm snow. Persistent strong westerly winds are cresting storm slabs in lee terrain. These slabs are producing cracking and small slab releases with ski cutting at treeline elevations. The Jan 6 layer of surface hoar and facets is reactive to stability tests in the easy range where storm slab conditions exist above the weak layer.
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.
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.