Avalanche Forecast

Archived

Mar 22nd, 2025–Mar 23rd, 2025

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 possible, human triggered probable.

Regions

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

A SPAW is in effect for the region.

Surface conditions are hiding a nasty persistent layer that's down about 60cm and guilty of causing many large avalanches. Don't try and outsmart the snowpack, instead avoid avalanche terrain altogether.

Confidence

High

Avalanche Summary

Natural activity continued yesterday afternoon with a sizeable 2.5 on the south aspect of CEGNF's peak (aka north peak of Mt. Murray).

Snowpack Summary

Not a lot of positive change in the past day or so. The recent storm snow has continued to settle and become quite stiff, which gives the illusion of improvement. In reality, this stiffening layer is increasing the avalanche hazard by creating wider propagations while potentially increasing the user's comfort with what seems like a stable snowpack. Do not trust the snow! The Jan 30th facet/depth hoar layer is remarkably poor with large grains that are acting as ball bearings. It is down 40-70cm in most areas. Tests on this layer and interface have been oddly consistent with catastrophic failures under moderate loads. In technical terms: compression tests reliably fail in the hard range with sudden collapses in the Jan 30th layer.

Weather Summary

Flurries will continue to blow through the region tonight and tomorrow. They'll offer up only a few centimeters, but enough to keep the snowpack fresh. South west valley bottom winds will be light, but gusty most of the day. Upper level winds will increase as the day goes on. Daytime high of -3 with moments of sunshine from time to time.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Avoid exposure to overhead avalanche terrain; avalanches may run surprisingly far.
Keep in mind that human triggering may persist as natural avalanches taper off.
Watch for newly formed and reactive wind slabs as you transition into wind-affected terrain.

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.