Avalanche Forecast

Archived

Mar 6th, 2024–Mar 7th, 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.

Natural activity continued today which tells us the snowpack needs significantly more time to sort itself out. Be patient, and don't let the blue skies lead to complacency.

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

Confidence

High

Avalanche Summary

Na activity continued with fresh windloading today. Most action was on east aspects, below alpine ridges and in steep terrain.

Snowpack Summary

No new snow overnight. Today the sun had enough punch to soften south facing snow. The moist snow surface may extend onto SW facing slopes by late afternoon. In some cases there may even be a sun crust. Steady moderate winds built fresh windslabs on easterly aspects that were avalanching naturally. Most of the action was starting immediately below ridges, but the slopes below were often triggered. Weather stations were all showing significant settlement in the last day or so. Feb 2 crust is down 70-90cm and still touchy. There is a concern for reloading on this layer. Even terrain that already avalanched could go again, especially with the new windloading. The deeper layers are once again with us and a consideration at treeline and above.

Weather Summary

Light cloud cover in the morning will give way to blue skies by late morning. Temperatures will start out cold, -24 and peak at -8 by late afternoon. The sun will offer a few more degrees, possibly even enough to soften the snow. Nothing for snow and light to moderate winds at ridgetop.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.
Remote triggering is a concern, watch out for adjacent and overhead slopes.
If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.

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.