Wind slabs continue to linger, and are slow to bond due to the cold temperatures. Watch for avalanche danger increasing with the new storm on Friday.
Confidence
Moderate - Due to the number of field observations on Wednesday
Weather Forecast
Mostly clear with some valley cloud on Wednesday morning. Light northeast winds becoming light northwest by Wednesday evening. No new snow expected and alpine temperatures around -20. Light snow starting Thursday evening combined with moderate southwest winds and alpine temperatures around -15. Overcast with light snow on Friday with alpine temperatures closer to -10.
Avalanche Summary
Natural avalanches up to size 2.0 continued to be reported on Monday from isolated areas in the north of the region in the Monashee ranges. At least one of these was triggered by a natural cornice fall. On Sunday, natural, skier, and explosive triggered storm slab avalanches up to size 1.5 were reported. The majority of this activity was occurring in wind loaded features on north and northeast aspects. On Saturday, natural storm slab and wind slab avalanches up to size 3 were reported in the region. These were typically 30-45cm thick and occurring on northerly aspects in the alpine and at treeline.
Snowpack Summary
The weekend storm system brought 30-60cm of new snow to the region with strong southwest wind in the alpine. Reactive wind slabs are expected to be lingering in leeward features in wind exposed terrain. In some areas, the recent storm snow may sit over a layer of small surface hoar. There is some uncertainty regarding the distribution of this surface hoar in the region but it was reported in a couple locations in the Monashees west of Revelstoke. The mid-November crust is now typically down 1-1.5m in the snowpack. While isolated snowpack tests show a potential weakness associated with the crust, in most areas the crust is well bonded to the surrounding snow and the layer is generally considered unreactive for the time being. It will be important to track how this layer evolves, especially during this period of cold weather.
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.