Regions
Banff Yoho Kootenay.
Heads up out there - lots of fresh snow combined with strong winds over the last week has elevated the avalanche hazard. The only thing keeping us from a full blown avalanche cycle is the cold air - be aware that human triggering is very likely.
Weather Forecast
Strong westerly flow continues but the main pulse of snowfall should taper by Friday morning. Friday looks like a mix of sun and clouds with winds tapering slightly and temperatures remaining cool (below -10). Another round of snow is expected for Saturday.
Snowpack Summary
Up to 50 cm of storm snow has been blown into widespread wind slabs by consistent, strong westerly winds over the past week. These unstable slabs overlie an interface of small facets, buried on Dec 19, and we expect avalanches can be easily triggered by people. Natural activity is expected over the next 24-hours in alpine areas.
Avalanche Summary
Poor visibility today, but the ski areas reported only small soft slabs within the recent snow inside the ski area boundary.
Confidence
Due to the number of field observations
Problems
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.
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.