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Avalanche Forecast

Archived

Dec 21st, 2025–Dec 22nd, 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 unlikely, human triggered possible.
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.

Enjoy the great skiing, but use caution when entering or exposing yourself to larger terrain, especially at higher elevations.

The avalanche hazard is slowly decreasing as the snowpack adjusts to the recent snowfall; however, recent explosive control still triggered large avalanches that ran to mid-runout in avalanche paths.

Confidence

Moderate

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

Avalanche Summary

No new natural avalanches were observed on Saturday, and explosive-triggered avalanches reported by the local ski areas were mostly small.

Previous highway avalanche control in Yoho and on the Sunshine Road Dec 18-19th produced results in the size 2.5-3 range.

On Dec 20th, the Lake Louise ski hill reported several explosive-triggered wind slabs up to 1.5, and Sunshine reported one size 3 persistent slab in previously uncontrolled terrain and one size 2.5 wind slab.

Snowpack Summary

Another 5-20 cm of new snow on Sunday, with the most along the divide. Ongoing moderate to strong SW winds continue to create wind slabs in lee areas at alpine and treeline elevations. 35-60 cm of recent storm snow sits over the Dec 15 interface that includes a melt freeze crust below ~2000 m.

The mid Nov facet/crust layers are down 80-140 cm and were active this week with numerous large natural and explosive controlled avalanches.

Treeline snow depths are between100-180 cm.

Weather Summary

Light flurries continue through Sunday night and Monday with total accumulations along the Divide of 5 to 10 cm. Moderate SW winds and treeline temperatures around -8°C forecasted for Monday.

Link to updated weather forecast tables from Environment Canada.

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.

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.