Avalanche Forecast

Archived

Dec 20th, 2025–Dec 21st, 2025

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

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

Kananaskis, Bow Valley, Highwood Pass, North 40, Spray - KLakes.

With more than 100cm of snow over the last 5 days, and strong winds, wind slabs are widespread at upper elevations. Although the natural avalanche cycle has tapered, slopes are primed for human triggering. Conservative terrain choices are advised.

Confidence

Avalanche Summary

No new avalanches were observed today, but visibility was limited. There is significant evidence of previous avalanche cycle up to size 3 over the last 4 days.

Snowpack Summary

Another 10cm of new snow has fallen in the last 24hrs. This brings the storm snow total to between 60 and 100cm over the last 5 days. Wind slabs are widespread in the Alpine and on lee and cross-loaded features at Treeline. These wind slabs are likely to be reactive to skier traffic. The November crust is now down 100-150cm, and is showing signs of faceting. Any avalanche triggered in the upper snowpack has a strong likelihood to step down to deeper instabilities.

Weather Summary

Sunday will be mainly cloudy with light snowfall. Total accumulations are expected to be near 5cm. Winds will start off in the strong range from the SW, and then settle down to moderate speeds near midday. Temperatures will be between -10 and -8C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
Be careful as you transition into wind-affected terrain.
Avoid areas with overhead hazard.

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.