Avalanche Forecast

Archived

Mar 4th, 2024–Mar 5th, 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 avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Regions

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

Increasing wind and fresh snow to move around will keep the avalanche rating elevated. This new snow is sitting on a persistent weak layer that can not be trusted. Evaluate each slope you travel through, whether across or below. Remote triggering from below remains likely. The Canmore hill remains closed for at least one more day while clean up crews work on clearing avalanche debris and plowing the road.

A Special Public Avalanche Warning is in effect and has been extended. Click the red SPAW link for details.

Confidence

High

Avalanche Summary

No field day today and no reports of activity.

Snowpack Summary

70-100 cm of recent snow is now overlying the Feb 3rd crust complex. Wind slabs can be expected in this new snow which will be easy to trigger with a skiers weight. A weak layer of faceted crystals also exists above and below this crust that has been producing moderate sheers. This new snow has overloaded this layer and caused a natural avalanche cycle. The November basal facets are alive and well and back on our radar as the February 2 rain crust is deteriorating and not locking in the weaknesses below as it once did. Skier weight has now been able to break through the Feb 2 rain crust in some places, which means that the basal facets can now be more easily affected.

Weather Summary

Tuesday:

Cloudy with sunny periods with possible flurries. Day time high of -16 with 20-30km West winds.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Avoid all avalanche terrain during periods of strong wind.
Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.

Problems

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.

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.