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Avalanche Forecast

Archived

Jan 15th, 2024–Jan 16th, 2024

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.

The thaw begins as temperatures warm through the week. Watch for increased wind Tuesday as it may add to the existing windslab problem or trigger small loose dry avalanches.

Confidence

Moderate

Avalanche Summary

Snow safety teams at Lake Louise and Sunshine triggered small windslabs on Monday in immediate lees with ski cuts and explosives. Several loose dry natural avalanches to size 1 were also reported.

Late last week, after the storm, there were several avalanches to size 2.5 on multiple aspects, and some are suspected of sliding on Dec 31 surface hoar, with some stepping down in the alpine to deeper layers. Most were 30-40cm deep, with some stepping down (80 cm thick).

Snowpack Summary

Mod-strong winds in the last week have formed slabs at treeline and above. 20-40 cm of recent snow over the Dec 31 layer that is comprised of surface hoar in sheltered areas and a spotty sun crust on steep solar slopes at treeline and above.

The mid-pack is supportive and contains two temperature/rain crusts from Dec 22nd and Dec 5th that reach as high as 2350 m.

The base of the snowpack consists of weak facets and depth hoar in most areas.

Treeline snow depths range from 80-120 cm.

Weather Summary

The winds have switched to a Westerly flow and the temperatures have started to warm. Expect moderate to strong W-NW winds Tuesday. Tuesday's highs will be around -15C with 2-4 cm of snow. Tuesday night into Wednesday we may see 10 cm.

For more information, click Mountain Weather Forecast.

Terrain and Travel Advice

  • Be carefull around freshly wind loaded features.
  • 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.