Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Regions
Kootenay Boundary.
We're moving into a period of elevated danger: where there is rain, watch out for loose wet ; where there is snow, watch out for storm slabs.
Confidence
Moderate - Intensity of incoming weather systems is uncertain
Weather Forecast
Warm and wet on Wednesday - Thursday. Cooling with light precipitation on Friday. WEDNESDAY: Rain to treeline (10mm) ; wet heavy snow in the alpine (10-15cm) / Strong southerly winds becoming moderate / Freezing level around 2000m / High temperatures to 0 Celsius. THURSDAY: Wet snow (20-30cm) / Moderate southeasterly winds / Freezing level around 1700 m. FRIDAY: Mostly cloudy with isolated flurries (local amounts to 10cm) / High temperatures to -2 Celsius / Light-moderate southerly winds / Freezing level around 1100 m.
Avalanche Summary
Several loose wet avalanches to Size 2 were reported on steep solar (south) aspects on Monday.Of particular note was a Size 3 natural avalanche on Wolf ridge near Kootenay pass on Monday - the sun's effect is significant! See the great photo in the MIN report (here).
Snowpack Summary
The recent warming and sunny conditions gave us a widespread sun crust on all but high northerly (and some westerly) aspects, where there is still some cold snow to be found. 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. Slabs were 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
Loose Wet
Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.
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.