Ski season seems to have finally arrived! Despite the new snow, remember to be conservative with terrain choice. A dry and windy December has left us with a thin snowpack that can vary a great deal in a short space.
Weather Forecast
Temperatures look to be fairly steady with freezing levels right around the townsite level. We expect the West winds to continue. 10 to 20 cm of snow is expected through to the weekend arriving mainly Thursday and Friday. This additional snow combined with the wind will likely cause and increase in the avalanche hazard as we approach the weekend.
Snowpack Summary
40 cm fell with the Storm Friday. Strong West winds blew Sunday and Moderate West winds continued to build fresh wind slabs Monday. Thin spotty slabs can be found behind exposed features well below treeline and more significant slabs exist at higher elevations. 30 to 40 cm off of the ground a weak layer of sugary faceted crystals remains a concern.
Avalanche Summary
Observations on a wildlife survey flight Sunday confirmed a widespread cycle of loose dry avalanches to sz 2 throughout the Park. In N and E alpine slopes that were rapidly loaded during the storm these minor slides triggered several examples of deep persistent slabs to sz 2.5 and up to 1.5m deep on steep, planar or unsupported slopes.
Confidence
Intensity of incoming weather systems is uncertain
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.
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.