Avalanche Forecast

Archived

Feb 6th, 2023–Feb 7th, 2023

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 possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Regions

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

Hazard levels at Treeline and above could trend towards HIGH if the region receives more snow than what is forecasted. Keep an eye on local conditions and adjust terrain choice accordingly.

Confidence

Moderate

Avalanche Summary

Nothing new reported or observed.

Snowpack Summary

Expected extreme winds and light snowfalls on Tuesday could change the surface snowpack conditions. Expect even more wind slabs to develop (or add to existing hard slabs) in the Alpine. At treeline watch for fresh surface wind slabs to develop through the day.

The rest of the snowpack has seen little change for weeks now. The concerning facets and depth hoar in the lower snowpack still exist, and while the mid-pack has enough density to carry the weight of a skier above 2100m, this is not necessarily the case at lower elevations.

Overall the snowpack condition of stiff and dense wind slabs on the surface, a reasonably dense mid-pack, all sitting on the "house of cards" of deeply buried weak layers, is still a recipe for concern. Full depth avalanches are still possible, especially where thin/shallow/rocky start zones are the potential trigger point.

Weather Summary

Tuesday will be cloudy with temps reaching -5C and light snow developing in the afternoon. Between 5 and 15cm are forecasted, but most models agree on lower amounts. Winds will be extreme and could be blowing at 100km/h out of the SW at ridgetop.

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.
Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
Be aware of the potential for surprisingly large avalanches due to deeply buried weak layers.

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.

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.