Avalanche Forecast

Archived

Dec 22nd, 2024–Dec 23rd, 2024

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Regions

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

Seek out sheltered areas less affected by recent winds. Avalanches in the upper snowpack have the potential to step down to deeper instabilities.

Confidence

High

Avalanche Summary

Last week several avalanches were observed along the Churchill Range on east faces in the alpine, up to size 2.5 and running to ground on the deep persistent layer. Some of these avalanches were caused by falling cornices.

Over the weekend the ski hill triggered two size 1.5 deep persistent avalanches with explosives and a small windslab.

Snowpack Summary

A dusting of new snow sits on up the 15cm that fell last week and was redistributed by southwest winds. This wind has loaded lee features, creating windslabs and stripped more exposed areas. In sheltered areas this snow sits on a weak layer of 7mm Surface Hoar.

The mid and lower snow pack has multiple layers of surface hoar in sheltered terrain, melt freeze crusts and facets. Two of these are the deep persistent slab interfaces near the ground.

Weather Summary

Monday

Mainly cloudy. Alpine temperature High of -5 °C. Ridge winds from the southwest, 15 km/h gusting to 45 km/h. Freezing level: 1600 metres.

Tuesday

Mainly cloudy with scattered flurries (up to 4 cm). Alpine temperature Low of -7 °C, High of -5 °C. Ridge wind from the southwest, 25 km/h gusting to 70 km/h. Freezing level at valley bottom.

Terrain and Travel Advice

Be mindful that deep instabilities are still present in the snowpack.
Be careful 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.

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.