Avalanche Forecast

Archived

Dec 6th, 2024–Dec 7th, 2024

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

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.

The Icefields Parkway will be closed from Parkers to Big Bend for avalanche control on Saturday December 7th from noon until 4pm. Check for updates on 511.alberta.ca

Incoming snowfall combined with strong winds will create wind slabs in leeward areas. Avalanches may have the potential to step down to deep persistent instabilities

Confidence

Moderate

Avalanche Summary

At Marmot Basin size 2 avalanches failing on the facets above the October 18 MFcr have been produced by large explosives in the alpine on E-S aspects.

Snowpack Summary

Up to 20cm of new snow will sit on a thin melt freeze crust that developed from the previous warm temperatures up to 2200m. The Nov 8th crust and facets are down 30-40 cm at tree-line and below. We have also found surface hoar (6mm) down 70cm at 2500m. The October crust is widespread and is found near the base of the snow pack with facets above and below. Snow depth is roughly 80 cm at treeline and tapers rapidly below.

Weather Summary

Saturday

Cloudy with flurries accumulating up to 15 cm.

Alpine high of -3 °C.

Southwest winds of 15 km/h gusting to 65 km/h at ridgetop.

Freezing level: 1500 metres.

Sunday

A mix of sun and cloud with isolated flurries.

Trace of precipitation.

Low -11 °C, High -8 °C in the alpine.

Mostly light ridge wind occasionally gusting to 55 km/h.

Freezing level at valley bottom.

Terrain and Travel Advice

Be mindful that deep instabilities are still present in the snowpack.
Watch for newly formed and reactive wind slabs 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.