Regions
Kootenay Boundary.
Buried weak layers sit beneath the new snow and have shown signs of being reactive to human triggers. Approach steep and convex terrain very cautiously.
Weather Forecast
TUESDAY: Mostly cloudy with some sunny breaks in the afternoon, light west wind, freezing level rising to around 1000 m.WEDNESDAY: Sunny, moderate southwest wind, freezing level rising to around 1300 m.THURSDAY: Increasing cloud and light flurries starting in the afternoon, moderate southwest wind, freezing level rising to around 1300 m.
Avalanche Summary
On Sunday, a skier triggered a large avalanche on a north treeline slope in the Rossland area that failed on a surface hoar layer 80 cm below the surface. Skiers in the Rossland area also experience whumpfing and ski cut a size 1 wind slab on a east aspect at 1700 m. Elsewhere in the region, a natural wind slab was observed on a northwest aspect at 2150 m and explosive control produced numerous size 2 storm slabs on south aspects.On Saturday, explosive control produced several size 1-2 storm slabs in the top 15-30 cm of snow.
Snowpack Summary
Isolated flurries have delivered sporadic and localized accumulations of new snow. Snowfall amounts from the past week are 40-60 cm with the exception of the Rossland area which received 80-100 cm.A mix of interfaces 50-100 cm below the surface will potentially remain reactive to human triggering and have given sudden results in recent snowpack tests. This includes small surface hoar on polar aspects and a sun crust on solar aspects.Two deeper weak layers that formed in January and December are gradually gaining strength. Several surface hoar and facet layers are buried 1 to 2 m below the surface and there is a crust/ facet interface near the base of the snowpack. No avalanches have been reported on these layers for a few weeks and they are thought to have gone dormant at this time.
Problems
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.
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.