Avalanche Forecast

Archived

Feb 23rd, 2024–Feb 24th, 2024

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Regions

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

The incoming storm is expected to bring continued strong winds and snowfall amounts of up to 10-20 cm between Friday evening and Monday morning. Use caution in areas which are exposed to overhead hazard and show evidence of wind slab development.

Confidence

Moderate

Avalanche Summary

Strong winds are contributing to cornice growth and are producing wind slabs in areas where snow is available for transport. Three recent avalanches were observed in the Churchill group originating from steep, rocky terrain and ranged in size from 1.5 to 2.5. Increased avalanche activity is expected throughout the weekend as snow accumulates and the strong winds continue.

Snowpack Summary

The multiple buried crusts within the upper snowpack are starting to lose strength in some areas. The Feb 3rd crust is down 15-30cm in wind protected areas. Strong ridgetop winds are producing wind slabs in the alpine where snow is available for transport. The Persistent and Deep Persistent weak layers continue to produce sudden fractures in tests and have been reactive to cornice failures in steep, rocky terrain.

Weather Summary

The Mountain Weather Forecast is available at Avalanche Canada https://avalanche.ca/weather/forecast

Saturday's Weather Flurries with accumulation of 5-10 cm.

Alpine temperature: High -5 °C.

Ridge wind west: 25 km/h gusting to 70 km/h.

Freezing level at valley bottom

Terrain and Travel Advice

Avoid shallow snowpack areas, rock outcroppings and steep convex terrain where triggering is most likely.
Minimize exposure to overhead avalanche terrain, large avalanches may reach the end of runout zones.

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.