Regions
Kootenay Boundary.
Weather Forecast
Tuesday: A couple centimetres possible overnight with up to 5-10cm possible throughout the day. Freezing levels could reach as high as 2000m in the evening with a temperature inversion, and moderate southwesterly alpine winds are expected. Wednesday: Continued light snowfall with moderate to strong southwesterly winds, and freezing levels around 1300m. Thursday: Generally dry with isolated flurries possible.
Avalanche Summary
Reports of avalanches are getting less frequent, but human triggering large avalanches associated with persistent weaknesses remains possible, including remote triggering. A skier recently remotely triggered an avalanche from 50m away and in many places shooting cracks and whumphing are further indicators of a very touchy, unstable snowpack.
Snowpack Summary
Compression tests have been producing easy to moderate sudden results on the mid-December surface hoar, down 30-80cm, and propagation tests have shown that avalanches associated with this persistent slab have a high propensity to propagate over large areas. above the mid-december weak layer of surface hoar. A storm snow weakness down 30cm also gave easy sudden results, recently formed wind slabs remain touchy, and in some places buried wind slabs are a concern.
Problems
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.
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.