Avalanche Forecast

Archived

Dec 8th, 2024–Dec 9th, 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.

Below Treeline

Natural avalanches unlikely.

Regions

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

The new snow will make for great skiing but the snowpack is still adjusting to this change. Keep your eyes out for windslabs and carefully assess the potential for triggering the deeper instabilities.

Ice climbers, watch for solar-triggered dry loose avalanches in steep, rocky terrain if the sun breaks through.

Confidence

Moderate

Avalanche Summary

Avalanche control on Saturday, December 7th, produced wind slabs up to size 2 near Parkers Ridge.

At Marmot Basin, size 2 avalanches were observed late last week, failing on facets above the October 18 melt-freeze crust. These were triggered by large explosives in the alpine. This indicates that this layer is a problem in certain areas and can be triggered in the right— or rather, the wrong— locations.

Snowpack Summary

Up to 25cm of new snow sits on a thin melt freeze crust. Strong winds have redistributed this snow into windslabs that may fail on the crust or on deeper layers. Three weak layers exist in the snowpack; the Nov 8th crust and facets that are down 30-40 cm at tree-line and below, surface hoar that has been found down 70cm at 2500m and the October crust which is found near the base of the snow pack with facets above and below. Snow depth is roughly 70 cm at treeline and tapers rapidly below.

Weather Summary

Monday

A mix of sun and cloud. Alpine temperature High -11 °C. Ridge wind from the west (10 km/h). Freezing level at valley bottom.

Tuesday

A mix of sun and cloud. Alpine temperature Low -11 °C and High -7 °C. Ridge wind from the west (10 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

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.

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.