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Avalanche Forecast

Archived

Dec 4th, 2023–Dec 5th, 2023

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

An avalanche cycle is expected to begin on Tuesday. Skiers should be choosing conservative terrain. Ice-climbers should be picking routes with no over-head hazard.

Confidence

No Rating

Avalanche Summary

Ski hills reported several small (size 1) ski-cut or explosive triggered wind-slab avalanches on Monday.

Snowpack Summary

Up to 15 cm of storm snow overlays well developed surface hoar, faceted snow, and sun-crusts on steep south aspects. Strong SW winds have formed fresh windslabs in alpine and tree-line locations. The mid and lower pack is generally weak and facetted. Snow depths range from 40-60 cm at tree-line and up to 90 cm in deeper alpine locations.

Weather Summary

A strong SW flow will bring snow, rising freezing levels and strong winds to the forecast area on Tuesday. Up to 30 cm of snow at tree-line expected by Wed morning. Freezing levels will spike to over 2000m on Tuesday before cooling somewhat by Wednesday. Winds will be strong from the SW.

For more information click Mountain Weather Forecast.

Terrain and Travel Advice

  • Pay attention to the wind, once it starts to blow fresh sensitive wind slabs are likely to form.
  • If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.

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.