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Avalanche Forecast

Archived

Dec 20th, 2025–Dec 21st, 2025

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

Regions

South Rockies, Bull, Crowsnest North, Crowsnest South, Elkford East, Elkford West.

Keep your guard up at all elevations. Wind slab formation has been extensive and could extend into openings below treeline.

Confidence

Moderate

  • Uncertainty is due to the limited number of field observations.

Avalanche Summary

On Friday, numerous explosive triggered persistent slab avalanches up to size 3 were reported in the alpine. They were failing on a crust down around 100 cm.

Several human and explosive triggered wind slabs up to size 2 were also reported on southeasterly aspects at treeline and above.

Snowpack Summary

5 to 10 cm of new snow brings recent snow totals to 50 to 70 cm. The recent snow and strong west winds have formed slabs overlying a 5 to 15 cm thick crust.

Above 1800 m, a prominent crust is down 100 to 150 cm deep.

Below 1800 m, the mid/lower snowpack is moist to the ground in most areas.

Weather Summary

Saturday Night
Cloudy with isolated flurries. 3 to 10 cm of snow. 50 km/h southwest ridgetop wind. Treeline temperature -7 °C. Freezing level valley bottom.

Sunday
Mostly cloudy. 35 km/h southwest ridgetop wind. Treeline temperature -7 °C. Freezing level valley bottom.

Monday
Mostly cloudy. 35 km/h southwest ridgetop wind. Treeline temperature -6 °C. Freezing level valley bottom.

Tuesday
Mostly cloudy. 40 km/h southwest ridgetop wind. Treeline temperature -5 °C. Freezing level valley bottom.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Make conservative terrain choices and avoid overhead hazard.
  • Watch for newly formed and reactive wind slabs as you transition into wind-affected terrain.
  • Keep your guard up at all elevations. Wind slab formation has been extensive and could extend into openings below treeline.
  • 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.