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Avalanche Forecast

Archived

Dec 28th, 2023–Dec 29th, 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.
Below Treeline
Natural avalanches unlikely.

Regions

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

Despite the "Moderate" avalanche danger the weak nature of the lower snowpack is still a concern. Human triggered avalanches are still possible as demonstrated by the full depth avalanche on Helen Shoulder on Wednesday. Caution around steeper features and larger alpine terrain is warranted.

Confidence

Moderate

Avalanche Summary

On Wednesday a group near Helen Shoulder remote triggered (from 30 m) a size 2 two avalanche on a south aspect at 2450m. The avalanche failed on the deep persistent layer near the ground.

Snowpack Summary

Wind effect, scouring and isolated hard wind slabs can be found in the alpine and some locations at treeline. Sheltered areas at and below treeline have large surface hoar over top of loose faceted snow. The mid-pack contains a rain-crust (below 2300m) in most areas and is somewhat settled and (mostly) supportive to skiers.

The base of the snowpack is a mix of weak facets and depth hoar.

Treeline snow depths range from 60-100 cm.

Weather Summary

A ridge of high pressure over the area will result in mostly clear skies and no forecasted snow through Saturday. Ridge-top winds will be light to moderate from the south-west. Freezing levels will be near valley bottom with a chance of an above freezing layer near 2500m on Saturday.

For more information, click Mountain Weather Forecast.

Terrain and Travel Advice

  • 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

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.