Avalanche Forecast

Archived

Jan 20th, 2023–Jan 22nd, 2023

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.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Regions

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

Use good discipline and don't push into bigger terrain. The snowpack is so variable (thick to thin) and thin weak areas are commonplace. These are the places where a skier could trigger the deeper slab problem.

Confidence

High

Avalanche Summary

No new avalanches reported or observed.

Snowpack Summary

A very thin crust exists just below the snow surface, but thankfully this crust disappears above 2000m. A buried layer of surface hoar down 15 to 30cm at treeline continues to produce shears, but the main concern in the snowpack is the persistent moderate shears failing down 70 to 80cm in the mid-November facets. Despite these layers gaining a bit of strength, the lower half of the snowpack remains very weak, and any avalanche initiated in the upper snowpack will likely step down to the lower weaknesses. Thin and rocky areas are of particular concern for triggering the deeper weak layers. Below 2100m the snowpack does not support the weight of a skier if you leave an established skin track.

Weather Summary

Saturday will see North winds becomming more westerly later in the day and temperatures in the -4C range throughout the day under partly cloudy skies. Winds will increase into the moderate range as they shift to the west mid-day. No snow is forecast for this area until Sunday where 5-8cm of snow is forecast to fall.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
Be aware of the potential for surprisingly large avalanches due to deeply buried weak layers.

Problems

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.

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.