Regions
Banff Yoho Kootenay.
10-20cm of storm snow has made for excellent skiing! Our main concerns are small buried wind slabs and sluffing in steep terrain. We removed the persistent slab problem because of a lack of activity on this layer, but the structural weakness remains.
Weather Forecast
A few more cm's of new snow are forecast for Saturday night and Sunday with continued light winds switching from E to SW overnight. Temperatures are forecast to remain cool (-5 to -15°C) depending on elevation with a slight increase Sunday afternoon.
Snowpack Summary
10-20 cm of storm snow with little wind effect sits over buried wind slabs in open areas at higher elevations, and over loose facets at lower elevations. Below this a firm mid-pack covers the Jan surface hoar layers that are rounding and inactive in tests. The deeper facet layers down 80-150 cm remain weak but are presently difficult to propagate.
Avalanche Summary
Small loose snow avalanches/sluffing has been reported in some steep treeline areas with the storm snow failing on the facets below and running a fair distance. A couple small buried wind slab failures have also been reported recently in steep terrain. The persistent weak layers have been inactive for two weeks and have been removed as a problem.
Confidence
Wind speed and direction is uncertain on Monday
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.