Regions
Kootenay Boundary.
Confidence
Fair - Due to variable weather conditions
Weather Forecast
Friday: Mostly clear / light to moderate southwest winds / freezing level at 300mSaturday: Mostly clear with increasing cloud and snowfall in the late afternoon / moderate northwest winds becoming strong from the west / freezing level at 700mSunday: moderate snowfall / moderate westerly winds / freezing level rising to 1300m
Avalanche Summary
Numerous size 1 to size 2 natural and explosive-controlled avalanches were reported in the region in the last 24 hours (mostly on north aspects above 2000m).
Snowpack Summary
On wednesday evening about 8cm of snow fell in the region adding to the 15-25 cm of snow that fell on tuesday. Tuesday's system was accompanied by strong to extreme winds from the southerly quarter producing reactive new wind slabs which are now the primary concern in the snowpack.Over last weekend up to 35cms of new snow fell. This new snow came in denser that the previous cold storm. This has been a recipe for continued storm slab instabilities as these slabs are reported to be quite reactive due to their poor bond on the cold snow interface below.I would suspect that time is helping to strengthen the recent storm and windslab problems, but I wouldn't write them off just yet as triggering is still a real possibility. Layers of concern deeper in the snowpack include a surface hoar/facet layer from mid-December and weak basal facets at the base of the snowpack in shallow snow areas. These layers have become less of a concern in the vast majority of locations. Last Saturday the mid- December layer is thought to have failed in several large avalanches that occurred in the Bonnington Range. This is a lingering layer of concern that reflects low probability but high consequence. Snowpack depths in the region are around 240 cm.
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.
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.