Regions
Kootenay Boundary.
Confidence
Fair - Timing, track, or intensity of incoming weather system is uncertain on Thursday
Weather Forecast
Thursday: Light snowfall accumulations up to 5cm. Alpine temperatures -3. Ridgetop winds light-moderate from the SW. Freezing levels rising to 1200 m.Friday: Mix of sun and cloud with intermittent flurries. Alpine temperatures near -5. winds moderate gusting to strong from the southwest. Freezing levels 1000 m.Saturday: Cloudy with some sunny periods, alpine temperatures -7 and light northwesterly winds.
Avalanche Summary
On Tuesday, explosive avalanche control initiated many size 1-1.5 slab avalanches on SE-SW aspects above 1600 m. On Monday, numerous natural avalanche activity was reported up to size 1.5 on NE-NW aspects above 2000 m. Skier triggered avalanches up to size 1 were not uncommon.
Snowpack Summary
Up to 20 cm of recent new snow and strong westerly have winds formed pockets of soft wind slab on lee slopes. A layer of surface hoar is buried 15-20 cm down, and has been reactive with the new snow, mainly causing loose dry sluffing from steeper terrain.A little deeper (between 35 - 50 cm below the surface) you may find a weak layer of surface hoar on sheltered slopes or a crust/facet combo on steep solar aspects. This layer is dormant, and there is not a deep enough overlying slab to create a significant hazard. That said I'd recommend keeping it on the radar, especially as the snow load above increases.In general, snowpack depths are below seasonal average with many slopes below treeline still reported to be below threshold for avalanche activity. A deeper snowpack is likely in the northern part of the region.
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.