Recently formed wind slabs remain sensitive to human triggering. Use extra caution in wind-affected terrain and avoid freshly wind-loaded pockets of snow.
Confidence
Moderate - Due to the number of field observations
Weather Forecast
Expect a mix of sun and cloud, isolated flurries and freezing levels at valley bottom for the forecast period. Ridgetop winds should spike to extreme from the southwest on Sunday evening, and then taper to moderate on Monday and Tuesday. For a more detailed weather overview, check out our Mountain Weather Forecast at avalanche.ca/weather.
Avalanche Summary
On Thursday, ski cutting produced isolated soft slab and loose dry avalanches to size 1 in the Castle area. On Wednesday, a natural size 1 wind slab was reported from a steep north-facing hanging snowfield in the Crowsnest Pass area. Also reported was a size 1.5 skier-triggered storm slab avalanche from the Elkford area. This occurred on a north aspect at 1950m elevation. The slab was 10cm thick and released on a layer of surface hoar.
Snowpack Summary
15-30cm of old storm snow 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.