Avalanche Forecast

Archived

Mar 21st, 2025–Mar 24th, 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.

The snowpack is untrustworthy at this time and as such, stick to low angle well supported slopes. If the sun comes out of Saturday, watch for decreases to stability on solar aspects.

Confidence

High

Avalanche Summary

A few new windslabs were observed from steep alpine areas on N and E aspects. Some loose dry slides were also being observed due to the moderate to strong winds at upper elevations.

Snowpack Summary

Snowfall over the past few days has added up to 5-8cm at treeline that fell under the influence of moderate to strong winds out of the SW. Watch for new windslabs up to 30cm thick overlying previous wind affect that formed earlier in the week in open areas. On Thursday this problem was showing cracking down 10-15cm along lee features around 2200m.

The snowpack is a 60-100cm dense upper pack that sits on top of a weak base that consists of 40-60cm of facetted crystals. This interface between the two is the January 30th interface and has produced repeatable sudden collapse test results over the past week. This layer (Jan 30th) has been failing on most of the recent avalanches. Unfortunately, do to the widespread nature of the weak crystals, the snowpack will be slow to change. Many recent avalanches have also stepped down to the basal facets and involved the entire snowpack. Repeated settlements (indicating that the snowpack is sensitive to a skiers weight) are still being encountered by forecasters as they travel, with many occurring at the treeline/below treeline features.

Weather Summary

Winds are forecast to drop to light out of the SW with isolated convective flurries throuhgout the day. Temperatures will climb to -5C with a freezing level forecast around 1500m. The sun has lots of power these days so if it comes up, watch for stability to decrease on the solar aspects.

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.