Avalanche Forecast

Archived

Dec 26th, 2020–Dec 27th, 2020

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

Below Threshold.

Treeline

Below Threshold.

Below Treeline

Below Threshold.

Regions

Kananaskis.

Stiff windslabs are widespread in alpine terrain. If these fail there is potential to step down to the basal November crust. Good sliding can be found at the treeline and below!

Confidence

High -

Weather Forecast

A few more cm's of snow is forecast to fall over the next 24hrs but accumulations are not expected to be significant. Temperatures will begin to cool and winds will continue in the light to moderate range out of the SW.

Avalanche Summary

No new avalanches were observed over the past 24hrs. An investigation of the Commonwealth ridge avalanche found a fracture line up to 2m deep in places that failed overlying the Nov crust running to the valley floor.

Snowpack Summary

5cm of snow over the past 24hrs is overlying the recent wind slabs that were developed during the Christmas break. Alpine areas are significantly wind affected with some ridgelines scrubbed down to rock and other filled with plump slabs. In some areas the the overburden of the new wind loaded snow awoke the facets overlying the Nov crust triggerring isolated deep slab avalanches up to sz 3. At treeline windslabs are more specific in nature and unsupported or crossloaded features should be places to avoid. Hollow or drummy sounds are a good indication you are moving into wind affected terrain.

Terrain and Travel

Be especially cautious as you transition into wind affected terrain.
Seek out wind sheltered terrain below treeline where you can avoid wind slabs and find great riding.
Avoid lee and cross-loaded terrain.
Avoid areas where the snow feels stiff and/or slabby.

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.

Cornices

Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.