Extensive wind effect has likely occurred at higher elevations. The best (and safest) riding may be found on sheltered slopes at treeline and below.
Confidence
Moderate - Due to the number of field observations
Weather Forecast
Light flurries (no more than 3 cm each day) are expected for all 3 days of the forecast period. Moderate southwest ridgetop winds forecast for Monday and Tuesday will ease to light and westerly by Wednesday. The freezing level should sit at valley bottom for the foreseeable future. For a more detailed weather discussion, please check-out our Mountain Weather Forecast at: avalanche.ca/weather.
Avalanche Summary
Observations were limited on Saturday and Sunday; however, an explosive-controlled size 2 wind slab was observed on a north-facing alpine slope. Continued strong winds and new snow from Sunday will likely be the driver for human-triggered wind slab avalanche activity over the next few days.
Snowpack Summary
Recently formed wind slabs can be found at treeline and in the alpine. Between 40 and 80cm below the surface you'll likely find a layer of weak buried surface hoar which is most prominent between 1400m and 1800m although it may extend higher in the mountains south of Invermere. Snow pit tests suggest that human triggering of this interface is becoming unlikely, although a release at this interface could be destructive in nature. Below this, the snowpack is thought to be mainly well settled.
Problems
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.