Avalanche activity on the persistent weak layers has decreased. However, it is important to stay vigilant. Maintain good travel habits and check out our forecaster blog on managing a persistent slab.
Come prepared with lots of warm layers, hot drinks and a headlamp when venturing out. Cold temperatures and short days can turn even small incidents like broken equipment into a very bad time.
Moderate westerly winds have built thin wind slabs at higher elevations. Be cautious when transitioning into wind-affected areas, especially around ridge crests and roll-overs in steep terrain.
There are two persistent weak layers within the snowpack: 30-50 cm of snow covers a weak layer of surface hoar on shaded aspects and a crust on steep solar aspects; many avalanches failed on this layer last week.
A second weak layer consists of surface hoar and facets from mid-November and is buried 60-90 cm in the region; this layer has recently surprised both professionals and recreationists with large human-triggered avalanches.
Read our featured blog to learn more about how to manage a persistent slab problem when travelling in the backcountry.
On Monday, two natural size 2 wind slab avalanches were observed, and several smaller wind slabs released in steep terrain. A size 2 slab avalanche was triggered remotely by riders, and two small size 1 wind slabs were triggered by skiers. Explosive control resulted in a small slab avalanche.
On Sunday, skiers triggered several small avalanches of size 1 below treeline about 40 cm deep. A small natural avalanche released on a northern aspect around 2000 m and there were several reports of whumpfing and shooting cracks.
On Saturday, skiers triggered a size 1 wind slab avalanche on a southeast aspect at 2300 m.
Snowpack depths at treeline range from 100-150 cm. In the alpine, snowpack depths are highly variable from extensive wind-affect in many locations.
Surface: 5-15 cm of recent snow overlies 5-8 mm surface hoar in sheltered areas. On steep solar slopes, new snow overlies a sun crust. Moderate westerly winds have built thin wind slabs in alpine lees.
Upper-pack: Cold temperatures are faceting the upper snowpack. 40-50 cm settling snow overlies a weak layer of 5 mm surface hoar in sheltered and shaded terrain and a sun crust on sunny south-facing slopes.
Mid-pack: Buried 60-90 cm deep, is a persistent weak layer of surface hoar, crust, and faceted crystals. This layer has been most reactive at treeline between 1700-2200 m, but it was also observed as low as 1450 m and on all aspects.
Lower-pack: Below the mid-November layer is a generally weak, faceted snowpack.
Tuesday Night
Decreasing cloud coverage, trace of snow, 20 km/h northerly wind, temperature low at -32 °C.
Wednesday
Mix of sun and some clouds, trace of new snow, 20 km/h northeast wind, temperature high around -26 °C.
Thursday
Sunny, 10 km/h easterly wind, temperature high at -27 °C.
Friday
Cloudy, 5-10 cm new snow, 40 km/h southerly wind, temperature high at -20 °C.
More details can be found in the Mountain Weather Forecast.
