Regions
Kootenay Boundary.
Make conservative terrain choices and be mindful of overhead hazard while the region's complex snowpack reacts to the spring-like temperatures.
Weather Forecast
A strong temperature inversion persist with an above freezing layer in the alpine. Valley cloud will linger bellow 1500 to 1800m. TUESDAY: sunny in the alpine, a freezing level of 3500m, light southwesterly winds. WEDNESDAY: sunny with scattered clouds with a possibility of light rain showers in the afternoon, a freezing level of 2800m, moderate westerly winds. THURSDAY: mainly cloudy, light westerly winds, freezing level of 2500m.
Avalanche Summary
Near Rossland, three size 1.5, skier triggered avalanches were reported over the weekend that occurred in wind loaded features between 1800m and 1900m on the late January surface hoar.
Snowpack Summary
Warm temperatures are encouraging the rapid settlement of the upper snow pack and moist snow can be found on solar aspects. A thin melt freeze crust may form on the surface overnight. Increasingly hard to trigger wind slabs can be found at ridgeline. A layer of surface hoar has been observed around Rosland and in the Bonnington Range, buried down 40cm, in open areas at and just below treeline. In most other parts of the region a rain crust can be found at this same depth that extends up as high as 2100m. Below this, a thick slab rests on a layer of surface hoar that was buried earlier in January and is now down 80-130 cm. This layer remains a concern in at and bellow treeline, producing sudden planar fractures in snowpack tests under moderate to heavy loads. A rain crust from early December sits near the base of the snowpack.
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.
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.
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.