Avalanche Forecast

Moderate - Forecast snowfall amounts are uncertain

MONDAY NIGHT: Flurries, 5-15 cm snow overnight. Light south-southwest wind increasing strong to extreme. Alpine low -7C, freezing level 500 m.TUESDAY: Scattered flurries, 5 cm. Moderate to strong southwest winds. Alpine high -3C, freezing level 1000 m.WEDNESDAY: Mainly cloudy with isolated flurries, trace accumulation. Moderate west-northwest wind gusting strong. Alpine high -2C, freezing level below 1000 m.THURSDAY: Cloudy with scattered flurries, trace to 5 cm accumulation. Moderate to strong southwest wind. Alpine high 0C, freezing level rising above 1500 m.

Wind transport is loading lee terrain, on Sunday natural wind slab avalanches were reported on northwest to east aspects. On Friday, a large (size 2) avalanche was observed on a southeast aspect just below ridgeline (see MIN report here). Continued cross-loading and variable wind transport has contributed to wind slab development and new slabs may be building on older, harder slabs.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.

15-30 cm recent snow is being redistributed by winds forming hard slabs and loading snow in lee and cross loaded terrain. At alpine and high treeline elevations, the recent snow covers a variable surface of wind-affected and faceted snow, and a weak layer of surface hoar in more protected areas. A rain crust/surface hoar combination is found below 1500 m, with warm temperatures settling the snowpack below treeline. Under the new snow interface, 25-50 cm of wind affected storm snow from over a week ago 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.