Regions
Kootenay Boundary.
Winds switching from southwest to northwest in the past few days created wind slabs on a variety of aspects.
Confidence
Moderate - Timing, track, or intensity of incoming weather system is uncertain on Thursday
Weather Forecast
TUESDAY NIGHT: Cloudy with clear periods, light wind, alpine temperatures drop to -8 C.WEDNESDAY: Cloudy with isolated flurries in the afternoon, light wind, alpine high temperatures around -3 C.THURSDAY: 15-20 cm of snow, moderate wind from the southwest, freezing level climbing to 1300 m, alpine high temperatures around -2 C.FRIDAY: Another 10-20 cm of snow, strong wind from the southwest, freezing level around 1200 m, alpine high temperatures around -4 C.
Avalanche Summary
On Monday, ski cutting produced a few small wind slabs on freshly wind loaded slopes. On the weekend, there were numerous reports thin storm slab avalanches (size 1-1.5) that were 15 cm deep, as well as some larger avalanches (size 2) where thicker wind deposits existed (up to 40 cm deep). These were reported as explosives triggered, naturally triggered, and some skier controlled.
Snowpack Summary
20-30 cm of snow sits on a thin sun crust on southerly aspects and small feathery surface hoar in sheltered areas.Beneath this, 50 to 100 cm of snow sits on a rain crust and a weak layer of feathery surface hoar and sugary facets that formed in early December. Although there has not been a reported avalanche on this layer in over a week, snowpack test results tell us that it is still possible to trigger. The lower snowpack is well-settled.
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.