Avalanche Forecast

Moderate - Forecast snowfall amounts are uncertain

Friday night: Cloudy with flurries bringing 5-10 cm of new snow. Light to moderate southeast winds. Saturday: Cloudy with scattered flurries bringing up to about 5 cm of new snow, continuing overnight. Strong to extreme southwest winds. Alpine high temperatures around -8.Sunday: Cloudy with decreasing, isolated flurries bringing a trace of new snow and new snow totals to 15-20 cm. Moderate west winds. Alpine high temperatures around -7.Monday: Mainly cloudy with isolated flurries and a possible trace of new snow. Light to moderate southwest winds. Alpine high temperatures around -7.

A large (size 2) persistent slab avalanche was remote (from a distance) triggered in the Kispiox area on Tuesday. It released over a buried layer of faceted (sugary) snow on a mellower (30 degree slope) southeast aspect at 1680 metres. This avalanche stands out from recent reports for the presence of a persistent weak layer at the failure plane, as well as for its remote trigger on a fairly mellow slope. Although it appears to be an isolated incident, it highlights the presence of a buried persistent weak layer that may remain preserved in northern parts of the region. Images of the slide suggest that wind loading was another contributing factor.Looking forward, watch for light new snow amounts being blown into thin but touchy new wind slabs progressively over the day on Saturday.

New snow is accumulating above mainly wind-affected and faceted (sugary snow) surfaces but also over a new weak layer of surface hoar in more protected areas. Last weekend's storm brought rain up to 1500 m, so the new snow is accumulating above a probable combo of surface hoar over rain crust below this elevation. Below this new snow interface, 25-50 cm of wind-redistributed storm snow from last weekend is expected to have formed a good bond with the underlying snowpack.A few buried weak layers that consist of surface hoar (feathery crystals) and/or faceted (sugary) snow may exist in some sheltered areas. The upper layer is about 35-60 cm deep and is a possible culprit in the Kispiox avalanche noted above. The next layer is likely 65-90 cm deep. The lower one is now approximately 100-150 cm deep. The bottom 30 to 50 cm of the snowpack consists of facets and crusts, particularly in areas where the snowpack is thin. It may be possible for storm slab avalanches to scrub down to ground in thin snowpack areas, resulting in large avalanches.