Dashboard Regions Weather Stations Radar Alerts Glossary
Contact About
Log In

Register for an account and never miss a forecast again!

Register

Avalanche Forecast

Archived

Dec 24th, 2022–Dec 25th, 2022

Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.

Regions

Banff Yoho Kootenay, Little Yoho, Banff, East Side 93N, Kootenay, Lake Louise, LLSA, Sunshine, West Side 93N, Field.

Natural avalanche activity will taper off Sunday, but human triggering will remain likely for the next while.

Increased winds, warmer temps, and new snow have added load to a very weak faceted snowpack. A conservative approach to terrain is recommended through the holidays until things improve.

Confidence

Moderate

Avalanche Summary

Newly formed wind slabs have been reactive to skier and explosive control in the past couple of days. Local ski hills and touring groups reported several new avalanches up to size 1.5 with failures occasionally stepping down into the basal facets to create larger slides. Wind-triggered sluffing in extreme terrain has also been observed.

Snowpack Summary

5-15 cm of new snow and wind are creating new slabs of varying thickness overtop of a weak faceted snowpack. The Dec 17 layer of facets and surface hoar is down 10-25 cm, and the Nov 16 facet, crust and surface hoar layer is down 30-60 cm, just above the weak basal facets. Both of these layers have been reactive in the past couple of days and avalanches triggered on either of these layers can quickly step down to the basal facets producing larger avalanches.

Total snowpack depths at treeline range from 60-120 cms.

Weather Summary

Another 5-10 cm of snow with extreme west winds is expected Saturday night into Sunday. On Sunday an upper ridge develops over the Rockies and the alpine winds will decrease slightly, becoming moderate-strong out of the west. Some flurries are expected Sunday along the divide with a mix of sun and cloud to the east. Alpine temperatures will stay between -5 to -10°C during the day, dropping to -10 to -15°C Sunday night.

Terrain and Travel Advice

  • Watch for fresh storm slabs building throughout the day.
  • Uncertainty is best managed through conservative terrain choices at this time.

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.