Regions
Kootenay Boundary.
Obvious signs of avalanche conditions have decreased, but surprisingly large avalanches are still possible.
Weather Forecast
A layer of warm air aloft will create warm alpine temperatures. Light amounts of precipitation are expected on Thursday night/ Friday. SW winds strengthen on Friday.
Avalanche Summary
On Saturday, skiers triggered numerous persistent slab avalanches to size 2 in the north of the region, in some cases remotely from a distance of 10m. On Sunday, a couple of persistent slab avalanches in the size 2.5 range were triggered between 2100 and 2300m from a distance of up to 100m. Avalanche activity has slowed, but there is still the potential for human-triggering of large avalanches, especially from areas where the snowpack transitions from thick to thin.
Snowpack Summary
Large surface hoar crystals are growing on the snow surface. Underneath this a thin frozen crust exists up to about 1900m. Our main concern continues to be a crust/surface hoar combo buried in mid-December. This touchy layer is 60-120cm down and has the potential to be triggered by people and produce surprisingly large avalanches. A facet/crust layer near the base of the snowpack has mostly been dormant, apart from recent activity in the Bonnington Range which suggests it may still be reactive in isolated terrain.
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.