Avalanche Forecast

Archived

Apr 11th, 2025–Apr 12th, 2025

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Below Threshold.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Below Threshold.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Below Threshold.

Regions

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

Newly formed windslabs will remain sensitive to trigger going into the weekend. Be diligent in assessing exposure to overhead hazard before entering terrain.

Even with cooling temperatures in at upper elevations, spring conditions remain below treeline.

Confidence

Moderate

Avalanche Summary

Large cornice failures and small windslabs have been observed at alpine elevations in the last 48 hours. Earlier this week a size 3 deep persistent slab avalanche was observed in the alpine on a N-NW aspect.

Snowpack Summary

Strong South winds and recent snow have formed new windslabs. The upper snowpack at treeline and below is a series of melt-freeze crusts and moist snow. The mid-pack and lower snowpack is dry, faceted and weak. The alpine and treeline snowpack on north aspects remains dry. Average treeline snow depth is around 100-150cm at the icefields area.

Weather Summary

Saturday

Mainly cloudy with scattered flurries.

Accumulation: 5 cm.

Alpine temperature: High -5 °C.

Ridge wind northwest: 15-30 km/h.

Freezing level: 1500 metres.

Sunday

A mix of sun and cloud.

Precipitation: Nil.

Alpine temperature: Low -12 °C, High -5 °C.

Ridge wind west: 10-30 km/h.

Freezing level: 1600 metres.

Monday

Cloudy with sunny periods and isolated flurries.

Precipitation: Trace.

Alpine temperature: Low -7 °C, High -1 °C.

Mostly light ridge wind occasionally gusting to 35 km/h.

Freezing level: 2200 metres.

Terrain and Travel Advice

Make conservative terrain choices and avoid overhead hazard.
Watch for newly formed and reactive wind slabs as you transition into wind-affected terrain.

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.