Avalanche Forecast

Archived

Mar 8th, 2020–Mar 9th, 2020

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Regions

Kananaskis.

This is the time to pull back as the natural cycle is tapering off. Skier triggering is likely with all of the wind slabs in the alpine and tree line.

Confidence

High -

Weather Forecast

Monday is forecast to be a mix of sun and cloud with moderate westerly winds. First thing in the morning in the alpine, the temperature will be -20c and rising to -9c as a high.

Avalanche Summary

The natural avalanche cycle continued on Sunday with numerous avalanches up to size 3 on all aspects and at all elevations. Mount Rundle was controlled by explosives on Sunday, producing large slides that covered the road.

Snowpack Summary

This recent storm has left us with 70-90cm of snow. This storm came in with lots of wind, thus the alpine is dominated by wind slabs, while treeline saw a lot of slab conditions in lee and cross loaded terrain. Expect some areas of wind drifting to be over one meter. Sunday saw a natural avalanche cycle, along with large results during explosive control. It will take some time for this recent storm snow to stabilize. At this time of year, solar radiation can be a huge factor for triggering natural avalanches on sun exposed slopes.

Terrain and Travel

Avoid freshly wind loaded terrain features.
Don't be too cavalier with decision making, storm slabs may remain sensitive to human triggering.
Avoid lee and cross-loaded terrain.
Make conservative terrain choices and avoid overhead hazard.
Extra caution is needed around cornices under the current conditions.
Be aware of the potential for large avalanches due to the presence of a deep persistent slab.

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.

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.

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.