Regions
Kootenay Boundary.
Local danger will depend on how much new snow falls on Monday. Expect danger to be considerable or higher if more than 40 cm of storm snow overlies the recently buried crust.
Confidence
Moderate - Forecast snowfall amounts are uncertain on Monday
Weather Forecast
Monday: Periods of snow with possible sunny breaks. Kootenay Pass could be in the bullseye with as much as 30-40 cm, while other areas should expect 10-20 cm. The freezing level is around 1500 m spiking to 1800 m late in the day. Winds are moderate to strong from the SW. Tuesday: Periods of snow (5-10 cm) with possible sunny breaks. The freezing level is around 1800 m and winds ease to light. Wednesday: Showers or flurries. The freezing level is around 1800-2000 m and winds are light.
Avalanche Summary
One size 2 accidentally triggered slab avalanche was reported in the Northern Rossland Range on Saturday. This avalanche was about 40 cm deep and was triggered on a NE aspect. One person was partially buried but escaped unharmed. Reports from other parts of the region included a few size 1 skier-controlled wind slabs and some small loose wet sluffs during a brief sunny break on Saturday.
Snowpack Summary
10-25 cm of new snow sits on a supportive crust at and below treeline, a breakable crust on south-facing slopes in the alpine, buried surface hoar in sheltered terrain, or wind affected surfaces. Moderate southerly winds may have created fresh dense wind slabs on exposed leeward slopes. An older buried crust can be found down 40cm extending well up into the alpine. At the same depth (around 40 cm), a buried surface hoar layer may be reactive on northerly aspects in the Rossland Range. Below this, a thick slab rests on a layer of surface hoar that was buried earlier in January. This layer is 80-130 cm deep and poses a low probability/ high consequence threat. It should remain on your radar, especially during periods of warming or rapid loading.
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.
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.