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Avalanche Forecast

Archived

Dec 29th, 2025–Dec 30th, 2025

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

Regions

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

Great skiing continues during a break in snowfall. Watch for reactive wind slabs in exposed alpine and treeline terrain, and be mindful of deep persistent weak layer when transitioning into areas with a thinner snowpack.

Confidence

Moderate

  • Uncertainty is due to the fact that deep persistent slabs are particularly difficult to forecast.

Avalanche Summary

No new natural avalanche observations were reported on Monday. Local ski hills triggered several size 2 wind slabs in the alpine using explosives. On Sunday, a skier-remote size 2 deep persistent slab was reported in the Lake Louise backcountry (see photo below). Although avalanche activity on the deep persistent layer has slowed, we continue to receive evidence of its reactivity.

Snowpack Summary

Variable winds have created fresh windslabs in alpine and open treeline terrain. In sheltered areas, recent storm snow (20-30cm) remains preserved.

There is 40-80 cm over the Dec 15 melt-freeze crust (which is present to ~1800 - 2000m), 80-160 cm over the November facet/crust interface, and, in thinner snowpack areas, facets at the base.

Treeline snow depths range from 100-200cm plus.

Weather Summary

A weak ridge of high pressure will linger over the forecast region on Tuesday. Expect a mix of sun and clouds, moderate to strong ridgetop winds, and no new precipitation. Over the next few days, temperatures will remain seasonably warm, with freezing levels near the valley bottom.

Link to the weather forecast

Terrain and Travel Advice

  • Watch for newly formed and reactive wind slabs as you transition into wind-affected terrain.
  • Be mindful that deep instabilities are still present and have produced recent large 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.