Regions
Kootenay Boundary.
Strong SW wind forecast for Saturday night and Sunday should add a touch of cohesion to the storm snow in wind exposed terrain. Carefully assess wind effect before committing to your line.
Confidence
Moderate - Wind speed and direction is uncertain on Sunday
Weather Forecast
A major storm has made landfall on the coast which should drive increasing winds and scattered flurries in the Kootenays. SATURDAY NIGHT: Moderate to strong W/SW winds. SUNDAY: Isolated convective flurries but no significant accumulations expected, freezing level at valley bottom, strong SW winds at ridgetop. MONDAY: Isolated flurries, but no significant precipitation expected, freezing level at valley bottom, light variable winds. TUESDAY: No significant precipitation expected, freezing level at valley bottom, light variable winds. For more detailed mountain weather information visit: avalanche.ca/weather
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
Cold temperatures are beginning to facet the snow surface which may be problematic down the line. In the last week the region received 35 to 70cm of storm snow is that slowly settling into a very soft slab. In some places this slab rests on the mid-December weak layer. This layer is just a crust in most locations, 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
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind 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.
Loose Dry
Loose Dry avalanches are the release of dry unconsolidated snow and typically occur within layers of soft snow near the surface of the snowpack. These avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs.