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Avalanche Forecast

Archived

Dec 26th, 2023–Dec 27th, 2023

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, human triggered possible.
Below Treeline
Natural avalanches unlikely.

Regions

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

Continued strong SW winds are taking their toll on an already thin snowpack. Use caution in wind-loaded features and areas with weak basal facets where human triggering is possible.

2023 has been mild and dry so far, fingers crossed for some snow in 2024!

Confidence

Moderate

Avalanche Summary

Wind loading and the deep persistent facets contributed to a close call near Bow Summit on Dec 23rd.

The Lake Louise ski hill snow safety team triggered several small windslabs in lee alpine terrain on Tuesday Dec. 26th.

Snowpack Summary

Wind effect and isolated hard windslabs can be found in the alpine and in isolated spots at treeline from continued moderate to strong SW winds. In sheltered areas at treeline and below, surface hoar and facetted snow sits over two distinct rain crusts in the upper snowpack.

The base of the snowpack is a mix of weak facets, depth hoar and a decomposing Oct crust. Low elevations consist of a re-frozen previously wet snowpack.

Treeline snow depths range from 50-95 cm.

Weather Summary

Mild, dry and windy is the name of the game over the next few days:

Wed: Winds moderate to strong from the SW. Possible above freezing layer between 2500m and 2700m breaking down by the evening.

Thurs & Friday: Strong W-SW winds. Freezing levels at valley bottom.

For more information, click Mountain Weather Forecast.

Terrain and Travel Advice

  • Be especially cautious as you transition into wind affected terrain.
  • Avalanche hazard may have improved, but be mindful that deep instabilities are still present.
  • Early season avalanches at any elevation have the potential to be particularly dangerous due to obstacles that are exposed or just below the surface.

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.