Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Regions
Kootenay Boundary.
Touchy storm slabs are reactive to human triggers. Use small slopes with low consequence to test the bond of the most recent snow.
Confidence
Moderate - Due to the number of field observations
Weather Forecast
Sunny and warm by Tuesday afternoon... and then some wet snow on Wednesday / Thursday. MONDAY: Sunny, warming significantly with alpine highs to +3 Celsius / Moderate southeasterly winds / Freezing level around 1800 m TUESDAY: Sunny with cloud developing in the afternoon / High temperatures to +5 Celsius / Light, southwesterly winds/ Freezing level around 2800 m. WEDNESDAY: Cloudy with some wet snow at higher elevations / Moderate southerly winds / Freezing level around 2500m.
Avalanche Summary
No new observed. See Whitewater Ski Patrol's great video (here) posted on the Backcountry Skiing Canada web site for a concise summary of details to Feb 9th, and some excellent video footage of a Size 2.5 avalanche running on the Goat Slide path near Whitewater (with crown height to 2.5m).
Snowpack Summary
At the end of last week up to 30cm additional snow fell (mostly near Nelson) and brought the recent storm snow total to 65-100cm, creating touchy storm slabs at all upper elevations and aspects. Snowfall amounts have been highest around Kootenay Pass. Slabs have been reported as 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. Snowpack tests near the Valhallas have given moderate, propagation-likely results down 50-70cms on the Feb 3rd interface. 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.
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.
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.