Regions
Banff Yoho Kootenay.
With steady light snow over the next few days the hazard will rise very gradually. Stay alert to these changes, watch for clues like sluffing, and continually monitor the reactivity of the surface snow over the buried facets and surface hoar.
Weather Forecast
The forecast is for cloudy skies with small amounts of snow, light to moderate West winds, and temperatures fairly steady in the -5 to -10'C range for the next three days. Total accumulations may reach 15-20cm in Western areas, but we will likely only see 5-10cm in the Eastern parts of our forecast region.
Snowpack Summary
15-40 cm of snow now sits over the Dec 15 layer of surface hoar or sun crust, and is beginning to develop soft slab properties with the warmer temperatures and wind. Below this the snowpack is heavily faceted with remnants of older crust's still lingering throughout. In steep gullies, loose faceted surface snow continues to be a significant concern
Avalanche Summary
A small skier triggered loose dry avalanche at treeline, and some thin small wind slabs in the alpine were reported on Sunday by the local ski areas. There have also been several small skier accidental avalanches involving thin wind slabs in the alpine during the past several days and reports of the December 15 layer slowly becoming more reactive.
Confidence
Intensity of incoming weather systems is uncertain on Tuesday
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.