Regions
Kootenay Boundary.
Total storm snow amounts are uncertain and falling on a variety of nasty layers. Timing of Saturdays storm is uncertain, if more snow comes earlier in the day consider the alpine danger to be HIGH.
Confidence
Moderate - Timing, track, or intensity of incoming weather system is uncertain
Weather Forecast
The strong Pacific jet continues to push a series of storms across the province through the weekend and into next week. The details of these fast moving storms are hard to pin-point, like track, timing and intensity. Confidence remains low on the actuals. Freezing levels will likely rise to 2200 m with each pulse then drop back to valley bottom. Saturday: Snow amounts 3-12 cm, strong SW winds, freezing levels rising through the day to 1500 m. Sunday: 10-20 cm of new snow, strong SW winds, freezing levels 1200 m. Monday: Snow 15-25 cm, strong SW winds, freezing levels 2000 m.
Avalanche Summary
On Friday reports indicated a surprisingly lack of avalanches, this could be due to lack of visibility. I suspect storm slabs are touchy and natural avalanches are likely through the weekend.
Snowpack Summary
Up to 40 cm of storm snow has buried old snow surfaces which comprise of stubborn wind slabs, crusts well defined at upper elevations especially on southerly aspects, loose faceted snow and surface hoar in sheltered areas. The new snow likely has a poor bond to the old snow. In some parts of the region a thick hard crust is reported to exist between 20 and 55 cm below the surface. For the time being, this hard crust is likely adding significant strength to the snowpack. That said, the combination of facets and surface hoar overlying a hard crust could become a reactive weak layer when it gets buried by new snow, and new snow its on its way. There is also another thick crust from early-November deeper in the snowpack. The limited reports we have received suggest that this crust is well bonded but you should investigate the snowpack in your local area before committing yourself to avalanche terrain.
Problems
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.