Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Regions
Banff Yoho Kootenay.
Many large natural, explosive and skier triggered avalanches over the past week. Cooler temperatures & cloud cover help, but still wise to avoid steep features and large slopes. Give it time and make conservative terrain choices this weekend.
Weather Forecast
Expect cloud cover and cooler temperatures through the weekend. Light snow tonight will have little impact.
Snowpack Summary
A surface windslab 10-30 cm thick continues to be reactive in tests on alpine lees on Friday. A 50-100 cm slab overlies the January 6th weak layer of surface hoar, facets and sun crust and snowpack tests indicate an unstable bond between the two. The lower snowpack is facetted and quite weak, especially in shallower areas.
Avalanche Summary
There have been many large natural and explosive triggered avalanches in the past week triggered by warm temperatures & solar radiation. Activity tapered Friday with the lack of solar input. A very close call on Twin Cairns in the Sunshine backcountry on Wednesday - a size 2.5 accidentally triggered took a skier for a ride & partially buried him.
Confidence
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.