Avalanche Forecast

Archived

Mar 12th, 2025–Mar 13th, 2025

Alpine

Natural and human triggered avalanches likely.

Treeline

Natural and human triggered avalanches likely.

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

Jasper, Brazeau, Churchill, Cirrus-Wilson, Fryatt, Icefields, Maligne, Marmot, Miette Lake, Pyramid.

More snow is on the way. If an avalanche path didn't slide during the last storm it is likely it will during this storm. Avoid overhead hazard and stick to simple terrain.

Confidence

Moderate

Avalanche Summary

On Monday, observations on the Icefields Parkway corridor revealed widespread natural avalanche activity from during the storm. Large slab avalanches, up to size 3.5, consisted of a mix of storm slab and persistent slab, with occasional step-downs to deeper instabilities. Avalanche control using explosives triggered large storm and persistent slabs with wide propagation. Some avalanche debris reached as far as the road.Tuesday Maligne patrol saw no new avalanches

Snowpack Summary

Up to 60 cm of new snow fell over the weekend. Below this fresh snow, the snowpack is complex, with multiple crusts and facet layers creating persistent weak layers. The bottom of the snowpack consists primarily of weak facets and depth hoar.

Weather Summary

Thursday

Snow.

Accumulation: 22 cm.

Alpine temperature: High -2 °C.

Ridge wind light to 25 km/h.

Freezing level: 1800 metres.

Friday

Flurries.

Accumulation: 6 cm.

Alpine temperature: Low -11 °C, High -9 °C.

Ridge wind light to 20 km/h.

Freezing level at valley bottom.

Terrain and Travel Advice

Use conservative route selection. Choose simple, low angle terrain with no overhead hazard.
Loose avalanches may step down to deeper layers, resulting in larger avalanches.
Avoid exposure to overhead avalanche terrain; avalanches may run surprisingly far.

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.

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.

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.