Have a safe and fun holiday.
Confidence
Fair - Intensity of incoming weather systems is uncertain
Weather Forecast
Expect a brief period of cooler and drier weather on Monday (flurries possible), before the next pulse of snow arrives on Tuesday (10-20cm). Snowfall becomes lighter on Wednesday. Winds are moderate to strong westerly to north-westerly, easing by Wednesday. Freezing levels are expected to fall from 1300m on Monday to near 800m by Tuesday.
Avalanche Summary
On Friday and Saturday, the storm snow was reacting very easily with skier traffic, creating small avalanches failing on the buried surface hoar (including one remote trigger with a partial burial). As the storm snow depth builds, it’s likely that avalanche activity will become larger and more widespread. Field observations have been limited during the storm.
Snowpack Summary
Storm snow and wind slabs have built up above a touchy layer of large surface hoar crystals. Below around 2100m, this surface hoar sits on a hard rain crust. Above 2100m the surface hoar sits on well settled and faceted snow. A thick rain crust with facets from early November is buried over 1 m down and may still be reactive in isolated areas.
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.
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.