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Avalanche Forecast

Archived

Jan 12th, 2025–Jan 13th, 2025

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

Watch for signs of wind slab formation and be cautious around thin areas where the deeper facets may still be triggered.

Confidence

Moderate

Avalanche Summary

Lake Louise triggered small wind slabs up to size 1.5 with explosives near ridge crests. A skier-triggered avalanche also occurred up Chickadee Valley on Saturday with no injuries.

Snowpack Summary

Since December 7, 5 to 10 cm of snow has fallen, and strong to extreme west winds on Friday have created slabs in the alpine and some treeline features. The recent snow sits on a layer of facets and surface hoar that persists in isolated locations.

The middle and bottom of the snowpack are weak, with depth hoar and facets near the ground.

An average of 60-100cm of snow can be found at treeline elevations.

Weather Summary

Monday brings moderate NW winds in the alpine, no snow, and treeline temperatures in the -4 to -9C range.

Terrain and Travel Advice

  • Watch for newly formed and reactive wind slabs as you transition into wind-affected terrain.
  • If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
  • Avoid thin areas like rocky outcrops where you're most likely to trigger avalanches on deep weak layers.

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.