Conditions are still ripe for human triggering at Treeline and above. Many clues of unstable snow have been observed in recent days. Give the snowpack more time to stabilize before committing to bigger terrain features.
Confidence
Fair - Freezing levels are uncertain
Weather Forecast
Wednesday will be a mix of sun and cloud and very light flurries with temperatures near -4 in the Alpine. Winds will be out of the West at 30km/h and the freezing level will climb to 1900m. Thursday and Friday will see warm temperatures and rising freezing levels.
Avalanche Summary
A significant natural avalanche cycle has occurred over the last 4 days. Some ski-triggered slides have also been reported. Activity has tapered off, but 2 new naturally triggered slabs were observed today on E aspects between 2300 and 2600m. These slabs were both size 2.0 and appeared to be storm snow slabs.
Snowpack Summary
12cm of new snow overnight brings recent storm snow totals to between 50 and 70cm at Treeline. This storm snow is generally settling rapidly due to mild temperatures. Wind slabs are present in open areas at Treeline and in the Alpine and these have been reactive to ski cutting in recent days and are also giving easy to moderate results in compression tests. Storm slabs are also an issue at all elevations with the interface (down 50 to 70cm) giving moderate compression test results today with very clean shear qualities. The surface snow is moist below 2050m on all aspects and higher on solar aspects. The snowpack in the valley floor did freeze overnight, but by midday the snowpack was moist and unsupportive. Recent cornice growth is also a concern as failures of cornices have triggered the deep persistent weak layer of the November facets in very large avalanches in recent days.
Problems
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind 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.
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.