Fresh wind slabs are primed for human triggers
Confidence
Moderate - Intensity of incoming weather systems is uncertain
Weather Forecast
Friday: A mix of sun and cloud, but dry, with freezing levels in valley bottoms and light southwesterly winds. Saturday: Mainly cloudy with light snow and moderate southwesterly winds in the afternoon. Freezing levels remaining in valley bottoms. Sunday: Mainly cloudy with light snow flurries, strong southwesterly winds and freezing levels in valley bottoms.
Avalanche Summary
West of the divide recent reports include a Size 1.5 skier triggered storm slab avalanche in the southern Elk Valley. But reports indicate no recent activity east of the divide.
Snowpack Summary
Another 5-10 cm of fresh snow adds to the previous storm snow that is bonding poorly to the old snow surface buried early January. However, east of the divide there has been much less recent snow and much more wind. Extensive scouring has been reported in some areas and and stiff wind slabs exist in lee features at treeline and in the alpine. In areas that have seen less extreme wind, recently formed wind slabs are likely softer, deeper, and may overlie surface hoar, facets, and/or a sun crust which formed at the start of January. The early December crust can be found down around 60-90cm. It is not currently expected to pose an avalanche problem but could wake-up in the future with substantial warming or heavy snow loading.
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.