Avalanche Forecast

Archived

Mar 10th, 2025–Mar 11th, 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

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

The snowpack will take time to adjust to the new load.Human-triggered avalanches are still likely. Considerable rating means DANGEROUS avalanche conditions. Careful snowpack evaluation, cautious route-finding, and conservative decision-making is essential.

Confidence

Moderate

Avalanche Summary

A road patrol and flight over the Icefields Parkway corridor revealed widespread natural avalanche activity 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.

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

Tuesday:Cloudy with sunny periods and isolated flurries. Precipitation: Trace. Alpine temperature: High -8 °C. Ridge wind southwest: 15-30 km/h. Freezing level at valley bottom.

Wednesday

Flurries. Accumulation: 6 cm. Alpine temperature: Low -8 °C, High -4 °C. Ridge wind southwest: 15 km/h gusting to 50 km/h. Freezing level: 1700 metres.

Terrain and Travel Advice

Use conservative route selection. Choose simple, low angle terrain with no overhead hazard.
Storm slabs in motion may step down to deeper layers resulting in large avalanches.
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.

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.