Regions
Kootenay Boundary.
Forecast snow, wind, and warming will increase the size and likelihood of triggering avalanches.
Confidence
Moderate - Forecast snowfall amounts are uncertain
Weather Forecast
WEDNESDAY: Another 5 to 10 cm new snow by Wed evening with moderate to strong SW or W winds. Temperatures warming with freezing level rising to around 1300m. THURSDAY: Yet another 5 to 10 cm by Thursday evening with SW winds. Continued warm with freezing level steady around 1300m FRIDAY: Still snowing with 5 to 20cm forecast by Friday evening with strong SW winds. Continued warm with freezing level unchanged (around 1300m).
Avalanche Summary
Explosive control at treeline and alpine elevations released storm slabs 30 to 60 cm deep on Monday. Loose dry sluffing up to size 1.5 from steep terrain at all elevations was also reported. Slab avalanche size and likelihood is expected to increase with forecast new snow, wind, and warming.
Snowpack Summary
Storm snow accumulations of 30 to 50 cm from the past few days are reported through the region with deepest amounts in eastern areas. Wind slabs have formed in exposed areas from shifting SW to NW winds. More snow and wind is forecast. Recent snow rests on a sun crust on steep sun-exposed slopes and large surface hoar shaded aspects. Below that are a variety crusts and thin surface hoar layers, depending on aspect and elevation, with the primary mid-pack feature being the mid-February surface hoar/sun crust down 75-100 cm. Areas with a shallow snowpack (less than around 170 cm) generally have a weak snowpack structure with a deep persistent weakness of facets near the ground.
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.