Avalanche Forecast

On Sunday, several large to very large (size 3 to 4) avalanches were triggered naturally on the basal facets. The avalanches were on all aspects and generally in alpine terrain between 2400 and 2900 m. See here for a video of a rider-triggered avalanche near Renshaw and another example here near Clearwater. Numerous shallower wind slabs were also triggered in alpine terrain.

These avalanches are similar to what we've seen over the past week, with persistent and deep persistent avalanches releasing on all the weak layers described in the Snowpack Summary. Most avalanches over the past week were large to very large (size 2 to 4), occurring between 1700 and 2400 m and on all aspects. See this MIN for a recent example and see here for information on a fatal skier-triggered avalanche incident from last week near Revelstoke.

See more on the potential of triggering deeper weak layers Forecasters' Blog.

New snow and strong westerly wind will form new wind slabs in lee terrain features. They will overly previously wind-affected snow from recent northeast wind. Storm slabs may begin to form in wind-sheltered terrain.

Two layers of surface hoar crystals and/or a melt-freeze crust may be found around 30 to 80 cm deep. Surface hoar is most likely found in wind-sheltered terrain around treeline and lower alpine elevations. The melt-freeze crust is found up to 1800 m on all aspects and into the alpine on sun-exposed slopes.

Large and weak facets from November are near the base of the snowpack, which continue to produce very large avalanches in the region.

Monday Night

Cloudy with snowfall, accumulation 5 to 15 cm with local enhancements possible, 20 to 30 km/h west wind, treeline temperature -12 °C.

Tuesday

Cloudy with snowfall, accumulation 5 to 15 cm with local enhancements possible, 20 to 40 km/h west wind, treeline temperature -12 °C.

Cloudy with snowfall, accumulation 10 to 20 cm with local enhancements possible, 20 to 40 km/h southwest wind, treeline temperature -10 °C.

Cloudy with snowfall, accumulation 5 to 10 cm, 30 to 40 km/h southwest wind, treeline temperature -6 °C.

More details can be found in the Mountain Weather Forecast.

• Wind slabs are most reactive during their formation.
• Be mindful that deep instabilities are still present and have produced recent large avalanches.
• Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.
• Surface hoar distribution is highly variable. Avoid generalizing your observations.
• Good day to make conservative terrain choices.