Kootenay Boundary

Touchy storm slabs reactive to human triggers. Use small slopes with low consequence to test the bond of the storm snow.

High -

Friday: 5-10 cm new snow / Strong, southwesterly winds / Freezing level around 1200 m.Saturday: Mostly cloudy with flurries / Moderate, westerly winds/ Freezing level hovering around 1000 m.Sunday: Mix of sun and cloud / Light to moderate, southwesterly winds / Freezing level around 1000 m.

On Wednesday, there was an explosive triggered size 3 persistent slab avalanche south of Nelson. The avalanche was triggered in a thin spot and the crown was 250 cm deep in some places. The weak layer was sugary facets sitting on a crust that was buried in mid-November. This is a good reminder that buried weak layers can remain dormant for months and then awaken like a sleeping dragon. It is possible for storm slab avalanches to step-down to these deeper weak layers resulting in very large and destructive avalanches. Thursday's storm has created touchy storm slabs that will remain likely to human trigger on Friday.

Another 20-30 cm of snow fell Thursday on top of the 45-85cm of recent storm snow which has created touchy storm slabs at all elevations and aspects. Snowfall amounts have been highest around Kootenay Pass. These slabs have been reported as being very reactive to human triggers and are sitting on a variety of surfaces; including scoured surfaces in wind exposed terrain, surface hoar(size 2-3 mm) in sheltered locations, and sun crust on steep solar aspects. 50-100 cm of snow now overlies the weak layer of surface hoar(feathery crystals) and facets(sugar snow) that was buried in mid-January. Areas with a shallower snowpack (less than 150 cm) have a generally weak snowpack structure with sugary facets near the ground. This includes shallow alpine slopes and most of the Rossland range. It is possible for storm slab avalanches to step-down to these deeper weak layers, resulting in large, destructive avalanches.