Avalanche Forecast

Archived

Dec 20th, 2024–Dec 21st, 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.

Alpine

Natural avalanches possible, human triggered probable.

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.

Large avalanches running to ground in the alpine have been observed in Jasper as a result of the new snow and winds. Avoid traveling in or under large wind affected slopes.

Small loose avalanches still have the potential to be hazardous above ice routes and terrain traps.

Confidence

Moderate

Avalanche Summary

Friday numerous loose dry avalanches up to size 1.5 were observed south of Parker Ridge on steep solar aspects. Thursday several avalanches were observed along the Churchill Range on east faces in alpine up to size 2.5 and running to ground. Some of these avalanches were caused by falling cornices.

Snowpack Summary

Strong southwest winds and 15-20 cm of recent snow have developed windslab in lee features. The 7mm Surface Hoar that formed last week is likely flattened by winds but assume it could be preserved under new snow in sheltered locations. With warm temperatures there is a possibility of a temperature crust on southern aspects at lower elevations. The mid and lower snow pack has multiple layers of surface hoar in sheltered terrain, melt freeze crusts and facets.

Weather Summary

Saturday

Mainly cloudy with isolated flurries. Precipitation: Trace. Alpine temperature: High -1 °C. Ridge wind southwest: 10 km/h. Freezing level: 2000 metres.

Sunday

Mainly cloudy with isolated flurries.Precipitation: Trace. Alpine temperature: Low -10 °C, High -3 °C. Ridge wind southwest: 15-30 km/h. Freezing level: 1600 metres.

Terrain and Travel Advice

Be mindful that deep instabilities are still present in the snowpack.
Be careful as you transition into wind-affected terrain.
Small avalanches may cause climbers to fall or bury belayers and gear.

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.

Loose Dry

Loose Dry avalanches are the release of dry unconsolidated snow and typically occur within layers of soft snow near the surface of the snowpack. These avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs.