Kootenay Boundary

Pockets of wind slab linger after fresh snow on Saturday night.

Moderate - Due to the number of field observations

MONDAY: Cloudy with scattered flurries and up to 10 cm of snow. Alpine temperatures warming to a couple degrees below zero and freezing level near 1500m. Mostly light winds but gusting occassionally to moderate.TUESDAY:  Cloudy with sunny periods. Alpine temperatures between -5 to -10 C overnight and near zero in the afternoon. Freezing level near 1600m. Light winds.WEDNESDAY:  Next storm arrives with 10 to 15 cm of snow at treeline and higher elevations. Alpine temperatures between -5 C and zero with freezing level remaining around 1600m. Light winds with moderate gusty periods.

On Saturday there was an accidentally triggered size 2 wind slab reported in the Valhallas. I think this kind of shallow wind slab in alpine terrain is representative of a lingering wind slab concern: localized pockets, lee and cross-loaded features, around 20 to 30 cm thick. Although not in this region, Saturday's fatal avalanche accident on Mt. Harvey (South Coast Mountains) highlights several of the risks posed by cornices: multi-ton snow boulders serve as large triggers potentially releasing big avalanches on the slopes below, and they can break well back making for tricky travel along ridge crests. It's all the more difficult to manage your risks when visibility is obscured in fog or heavy snow, if the easiest pathway (flat, hard snow, open straight line) is within the danger zone, or when they're so big that you need to be 10 or 15 or more metres back from the edge to remain safe. Also in the Valhallas, a natural cornice release triggered a size 2.5 avalanche on the steep rocky slope below that involved most all of the winter's snowpack.

In high elevation terrain, recent moderate southerly winds and new snowfall has formed wind slabs in leeward features. At lower elevations and on sun exposed slopes, there is likely moist or wet snow sitting on top of several well bonded crust layers in the upper snowpack.