Avalanche Forecast

Archived

Feb 26th, 2024–Feb 27th, 2024

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches possible, human triggered probable.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches possible, human triggered probable.

Alpine

Natural and human triggered avalanches likely.

Treeline

Natural and human triggered avalanches likely.

Below Treeline

Natural avalanches possible, human triggered probable.

Regions

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

Approach all avalanche terrain with extreme caution. We are nearing a natural avalanche cycle.

Confidence

Moderate

Avalanche Summary

No avalanche activity was observed during the field day. This was surprising, given the amount of snow and wind. Maybe it is just waiting for a light trigger like a skier.

Snowpack Summary

20-30cm of snow has fallen in this last storm and has become a wind slab in all exposed areas. This new wind slab and storm snow sits on top of a variety of layers:

The February 24 storm interface which is down about 20-30cm and consists of suncrust, previous wind slab. This layer will be sensitive to skier triggering.
The February 3 Rain crust which is down about 40-50cm. This crust has started to develop facets on top of it which is a perfect layer for sliding.

We are at or nearing the critical load of new snow or slab development for a natural avalanche cycle to start.

Weather Summary

Tuesday will be a mixed bag of cloud, sun and isolated flurries. Expect cold temperatures in the morning of -26c in the alpine and then warming to -15c. Winds are forecast to be 25-30km/hr from the SW

Wednesday to Friday: Periods of snow with up to 45cm by Friday. Stay tuned for snow amounts and how it will impact the avalanche hazard...

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
Avoid traveling in runout zones. Avalanches have the potential to run to the valley floor.
Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.

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.

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.

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.