Regions
Banff Yoho Kootenay.
Small amounts of snow will hopefully start to cover all those tracks out there! The biggest hazard is triggering a facet avalanche which can have bigger consequences in terrain traps. SH
Weather Forecast
Only a trace to a few cm expected into Sunday morning. West winds will spike briefly both tonight (Saturday) and Sunday night but will diminish during the day. On Sunday, valley temperatures will be in the -2 to -5 range and alpine temps will be in the -8 to -10 range.
Snowpack Summary
There is now10-15 cm over the Jan 6 combination of surface hoar, facets and sun crust depending on aspect and elevation. Small wind slabs should be expected along high alpine ridge crests resulting mainly from West winds. The snowpack is facetting. Upper layers are very weak however the snowpack remains supportive in deeper areas (> 1m snowpack)
Avalanche Summary
Loose dry events to size 1.5 in steep terrain require only a very light trigger as the weak facetted surface layers sluff. These can run a surprising distance. There have been a few small wind slabs reported in recent days out of alpine ridge crests but they remain isolated and "sluggish" to move.
Problems
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.
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.