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Avalanche Forecast

Archived

Dec 11th, 2025–Dec 14th, 2025

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

Regions

Waterton Lakes, Waterton.

This week was marked by a large atmospheric river that brough high freezing levels and over 1m of snow to the alpine. With all this new load careful travel and snowpack assessment will be required. Below treeline this precip fell as rain and flushed much of the snowpack out. Travel on skis below treeline will be very difficult.

Confidence

Low

Avalanche Summary

Numerous natural slab and wet loose avalanches were observed this week during the storm with results up to size 3.

Snowpack Summary

In the alpine up to 100cm of snow fell between Mon-Thurs with strong SW winds forming windslabs in lee features. A crust and facet layer make up the bottom of the snowpack, treeline and above, in isolated places that held early season snow. Below 1700m this weeks precip fell as rain/snow and saturated the snowpack. With cooler temps this has begun to refreeze into crust. Alpine snowpack depths 70-150cm however below treeline is as low as 15cm with vegetation and logs exposed.

Weather Summary

Fri

Overcast skies with 10cm snow. Winds 40km/h SW. Valley bottom temps around -5

Sat

Clearing by noon with some AM flurries. Winds increase to 30km/h SW. Valley temps 0 degrees

Sun

Broken skies, no significant precipitation expected. Winds 30km/h SW. Temps remaining warm at valley bottom, high +2

For current weather forecast, please see Mountain Weather Forecast

Current ECC weather table can be found Here

Terrain and Travel Advice

  • If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.

Problems

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.

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.