Fresh wind slabs will be building on Sunday.
Wind slabs could step down to a deeper persistent weak layer triggering a much larger avalanche.
New snow overlies a variety of surfaces, including surface hoar, facets, or a crust, which may make wind slabs more reactive and take longer to bond.
Several persistent weak layers exist within the snowpack and have been the cause of recent large avalanches in the region. The greatest concern for triggering these layers is on upper elevation north and east facing slopes.
Fri: Several large to very large (size 2-3) persistent slab avalanches occurred in the region. All of them initiated in the alpine.
Thurs: A large (size 2) naturally-triggered persistent slab near Invermere and a size 2.5 persistent slab near Kimberley were observed.
Tues: Avalanche control produced large avalanches (up to size 3.5) in the central-western part of the region.
Looking forward: Wind slabs and persistent slabs are expected to remain triggerable on Sunday.
15 - 30 cm of snow accumulated over the last few days forming wind slabs at upper elevations. An additional 5 - 10 cm of new snow combined with strong southwest winds is forecast to fall overnight and through Sunday. This is expected to create fresh wind slabs on wind-loaded north and east facing slopes near ridgetops.
Combined, the recent snow covers a crust on sunny slopes and lower elevations, and surface hoar or facets on sheltered and shady upper elevations. Several weak layers consisting of a crust, facets or surface hoar from February and January remain a concern, buried 30 to 60 cm. A layer of facets from early December is buried 70 to 120 cm. In many areas, facets or depth hoar make up the base of the snowpack.
Saturday Night
Mostly cloudy with 1 to 5 cm of snow. 10 to 25 to 40 km/h southwest ridgetop winds. Treeline temperature -9 °C.
Sunday
Mostly cloudy, with 2 to 5 cm of snow. 20 to 30 km/h south ridgetop winds. Treeline temperature -5 °C.
Monday
A mix of sun and clouds. 15 to 30 km/h west ridgetop winds. Treeline temperature -5 °C.
Tuesday
A mix of sun and cloud. 10 to 25 km/h west ridgetop winds. Treeline temperature -7 °C.
More details can be found in the Mountain Weather Forecast.
