Regions
Banff Yoho Kootenay.
More new snow has arrived than expected in most areas with touchy new slabs observed in the alpine. Expect conditions to have changed significantly from the last few weeks.
Weather Forecast
Much more snow than was expected arrived in the majority of the region Friday with moderate to strong SW - W winds. Saturday, look for winds to back off and snow to stop with partly cloudy skies remaining. Temperatures will be steady at around -10 to -15 at treeline through Saturday before warming about 5 degrees overall Sunday afternoon.
Snowpack Summary
A trace to 20 cm of new snow came with moderate to strong SW-W winds. This sits over weak surface facets, previous wind effect and crusts isolated to steep solar slopes. Weaker layers like the Jan.17 surface hoar/facets linger down 40-60 cm in some locations, but are currently lying dormant. A weak basal snowpack exists in thin snowpack areas.
Avalanche Summary
A flight in the Lake Louise area this morning saw several examples of loose dry avalanches running a good distance that had failed with the new loading. While only a few examples of fresh slabs were seen on the flight with poor visibility, the ski hills reported working with a touchy new slab up to 40 cm deep, up to 40m wide and running up to 150m.
Confidence
Due to the number of field observations on Friday
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.