Wind slabs may have large propagation due to a weak layer of surface hoar or crust underneath.
Conservative terrain choice is recommended.
Rider-triggerable wind slabs may be found below ridgetops and in cross-loaded terrain. A layer of surface hoar buried in early January may be reaching a tipping point as the load above it increases, which could lead to wide propagations.
Dry loose avalanches have been starting in extreme terrain and gaining mass in the loose snow.
On Monday, a snowcat west of Revelstoke triggered a small slab which failed on the early December weak layer. It was at treeline on a west aspect.
As well as a very large (size 3) wind slab avalanche triggered by a skier in neighbouring Glacier Park.
On Saturday there were numerous, small accidentally triggered wind slab avalanches. Surface hoar was noted as the failure layer.
Saturday's moderate northwest wind has affected the surface in open areas at all elevations.
In sheltered terrain, 30 to 40 cm of settling snow sits on a layer of weak, feathery surface hoar crystals, possibly even into the alpine. On sunny slopes, there may be a crust as well.
A crust/facet/surface hoar layer buried in early December may be found 90 to 160 cm deep.
Monday Night
Clear. 20 to 40 km/h west ridgetop wind. Treeline temperature -8 °C.
Tuesday
Clear, cloud building in the afternoon. 20 to 30 km/h west ridgetop wind. Treeline temperature -1 °C.
Wednesday
A mix of sun and cloud with 1 cm of snow. 10 to 20 km/h southwest ridgetop wind. Possible temperature inversion. Treeline temperature 0 °C.
Thursday
A mix of sun and cloud with up to 5 cm of snow. 20 to 30 km/h northwest ridgetop wind. Treeline temperature -7 °C.
More details can be found in the Mountain Weather Forecast.
