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Avalanche Forecast

Archived

Jan 21st, 2022–Jan 22nd, 2022

Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely, human triggered possible.

Regions

Banff Yoho Kootenay.

http://www.pc.gc.ca/apps/links/goto_e.asp?destination=http://avalanche.ca/spaw/2022-01-20-spaw

Steep solar aspects could see increase natural avalanche activity this weekend as clear skies and warmer temps heat southerly aspects.

Weather Forecast

A ridge of high pressure over the forecast region will bring clear skies this weekend. Winds at ridge crest will gradually increase late Saturday, with values reaching strong to extreme by Sunday. Freezing levels will stay near valley bottom this weekend.

Snowpack Summary

Recent wind and new snow have created fresh wind slabs in the alpine and some tree-line areas. Much of the new snow overlay a facet interface formed in late December. The Dec. 2 crust and facets are generally 60-90cm deep and still producing results in snowpack tests. Some thin snowpack areas have lingering basal depth hoar and facets.

Avalanche Summary

Avalanche control in Kootenay and on the Sunshine road Friday produced several results to size 2 at alpine and tree line elevations. The predominant weak layer triggered, were surface winds slabs 20-40cm deep. This past week we have observed several large avalanches failing on the persistent avalanche problem.

Confidence

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.

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.