Regions
Banff Yoho Kootenay.
The long period of good stability is ending. The Jan. 6th layer will likely be touchy for some time. Moderate alpine winds on Tues will keep the alpine hazard elevated, and a large snowfall on Tues PM/ Wed will raise the hazard significantly.
Weather Forecast
Tues: Alpine temps -10/-15. Alpine winds mod to strong SW. 2-4 cms new snow.Tues overnight and Wed: Alpine temps -10/-15. Alpine winds mod W. 20-35 cms new snow!!Thurs: Alpine temps -15/-20. Alpine winds becoming light N. Clearing skies.
Snowpack Summary
5-30 cm of new snow overlies the Jan. 6th interface which is either a facet, surface hoar, or hard slab layer. Moderate S/SW winds have created soft slabs in exposed alpine and treeline areas. Field reports say these new slabs range from touchy to stubborn to trigger. The lower snowpack is facetted E of the divide and well settled to the W.
Avalanche Summary
A helicopter bombing mission on the sunshine road today produced minimal results to size 2, mostly being loose dry avalanches in the facets. The ski hills are reporting ski cutting newly formed soft slabs to size 1 and newly formed cornices.
Confidence
Forecast snowfall amounts are uncertain
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.
Loose Dry
Loose Dry avalanches are the release of dry unconsolidated snow and typically occur within layers of soft snow near the surface of the snowpack. These avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs.