Regions
Kootenay Boundary.
Storm slabs should be getting less and less sensitize to human triggering, but you need to exercise due diligence and carefully investigate the new/old snow interface before committing to the bigger more complex lines.
Confidence
Moderate - Wind speed and direction is uncertain on Sunday
Weather Forecast
A major storm will impact the Northwest Coast on Saturday, the scraps of that system may bring isolated convective flurries to the Kootenay’s over the weekend. SATURDAY: No significant snowfall expected, freezing level at valley bottom, light S/SW winds. SUNDAY: Isolated convective flurries but no significant accumulations expected, freezing level at valley bottom, light SW winds at treeline, initially strong SW winds at ridgetop, easing throughout the day. MONDAY: No significant precipitation expected, freezing level at valley bottom, light variable winds.
Avalanche Summary
Recent avalanche activity has been limited to fast running loose snow avalanches on steep features and small wind slabs in the alpine.
Snowpack Summary
35 to 70cm of storm snow is slowly settling into a very soft slab that rests on the mid-December weak layer. This layer is just a crust in most places, but in Kootenay Pass there is a surface hoar interface on or just above this crust that is most prevalent between 1800 and 2000m. At treeline the early December crust is down around 70 to 110cm, and it's thick and supportive nature is likely capping any deeper weaknesses in most places. However, recent observations from the Nelson area indicate that there are facets on this crust, so it's an interface to watch as we move into the New Year. The lower snowpack is thought to be well settled.
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.