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Avalanche Forecast

Archived

Jan 24th, 2024–Jan 25th, 2024

Alpine
Natural avalanches possible, human triggered probable.
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.
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.

Recently formed soft and hard slabs overlie a touchy weak layer 10-40cm below the surface are becoming more reactive.

The snowpack is becoming increasingly more complex, this is not a time to be stepping out into complex terrain.

Confidence

Moderate

Avalanche Summary

Lake Louise ski hill had explosive results up to size 2 on the basal weakness out of the steep terrain.

Sluffing continues out of steep terrain.

Snowpack Summary

Surface level hard and soft slabs have formed due to recent warming and strong winds. These overlie touchy weak layers ~10cm and ~40cm below the surface that produce very easy sudden collapse results on compression tests.

The midpack offers some strength and features two crusts that persist as high as 2350m.

The lower part of the snowpack has weak facets and depth hoar and widespread whumphing has been observed in many locations over the last week.

Parks Jan 24th snow profile

Weather Summary

Wed night and Thurs: Scattered flurries across the Range. Trace accumulations. Moderate to strong SW ridgetop winds. Freezing levels at valley bottom.

Friday: Isolated flurries across the Range. Nil accumulations. Mod to strong westerly to SW ridgetop winds. Freezing levels rising to 1500-1800 m.

Sat/Sun: Scattered flurries, trace accumulations. Mod to strong SW winds. Freezing levels rising to 1800-2200 m

Terrain and Travel Advice

  • Avoid areas where the snow feels stiff and/or slabby.
  • If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.

Problems

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.

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.