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Avalanche Forecast

Archived

Dec 18th, 2023–Dec 19th, 2023

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

Regions

Banff Yoho Kootenay, Little Yoho, Banff, East Side 93N, Kootenay, Lake Louise, LLSA, Sunshine, West Side 93N, Field.

Natural avalanche activity has abated, but human triggered avalanches are still possible. Pay attention to wind loading as you make your way into the alpine and continue to make conservative terrain choices.

Confidence

No Rating

Avalanche Summary

A large natural avalanche was observed in the alpine on Mount Fairview on Friday. Sunshine reported 2 small natural avalanches (size 1) in the alpine on Sunday. Otherwise no new natural avalanches reported since Saturday.

Snowpack Summary

Recent mod-strong SW winds and last Thursday's storm snow have created wind slabs in the alpine and exposed tree-line terrain. Below this is a semi-supportive mid-pack that may include a rain crust of various thickness up to 2300m. The base of the snowpack consists of weak facets and depth hoar. Tree-line snow depths range from 50-90 cm.

Weather Summary

Light flurries with minimal accumulation are forecasted along the continental divide through Friday. Ridgetop winds will be SW, light to moderate on Tuesday, picking up a bit on Wednesday and then forecasted to be strong on Thursday. Temperatures will be relatively mild with freezing levels near valley bottom.

For more information, click Mountain Weather Forecast.

Terrain and Travel Advice

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.

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.

Deep Persistent Slabs

Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.