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Avalanche Forecast

Archived

Dec 31st, 2025–Jan 1st, 2026

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, Banff, East Side 93N, 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.

We have limited recent alpine observations.

Confidence

High

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

Avalanche Summary

New natural wind slabs up to size 1.5 were observed today in the Kootenay. Ski hills reported mixed results from explosive control, with generally fewer and smaller avalanches than expected. However, Lake Louise patrol triggered a size 3 deep persistent slab that failed to ground. This fits the recent trend: low overall reactivity, but the potential remains for large, destructive avalanches in isolated areas.

Snowpack Summary

Strong winds have continued to develop windslabs in alpine and open treeline terrain. In sheltered areas, recent storm snow (20-30 cm) remains preserved.

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

Treeline snow depths range from 100-200+ cm.

Weather Summary

A weak ridge of high pressure will remain in place through Thursday, bringing a mix of sun and cloud, moderate ridge-top winds, and freezing levels near valley bottom. Precipitation is expected to begin Friday, with forecast accumulations of 5–10 cm by Saturday.

Link to the 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.
  • Avoid thin areas like rocky outcrops where you're most likely to trigger avalanches on deep weak layers.

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.