Regions
Kootenay Boundary.
Recent avalanches big enough to bury or injure a person have been triggered on a buried crust. Maintain a cautious approach to travel this weekend.
Confidence
Fair - Timing or intensity of solar radiation is uncertain
Weather Forecast
Synopsis: Generally very fine weather with cool overnight temperatures and warm, sunny days.Saturday: Cloud lingering, but also some clear breaks. No precipitation. Freezing level 1400 m. Mostly light, but occasionally gusty, northerly winds.Sunday and Monday: Clear and sunny. Freezing level around 1600 m. Light southwesterly winds.
Avalanche Summary
On Thursday, several size 1.5-2 avalanches were either deliberately ski-cut or accidentally triggered on a range of aspects at elevations from 1800 - 2100 m. All failures were on a crust, typically buried 20-40 cm deep. Explosive avalanche control produced similar results.
Snowpack Summary
Between 20 and 60 cm recent storm snow rests on a thick crust that exists up to ridge top. The bond between the storm snow and the crust appears to be poor above 1800 m. In some places, you may find an additional, thinner crust within the top 60 cm snow. A buried surface hoar layer lies buried approximately 80 cm below the surface and continues to fail in a sudden planar fashion when tested. However, in most places it is likely not a concern due to the thick supportive crust that lies above it. Potentially large fragile cornices loom over many slopes.
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.
Loose Wet
Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.