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Avalanche Forecast

Archived

Jan 26th, 2024–Jan 27th, 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 possible, human triggered probable.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural and human triggered avalanches likely.
Below Treeline
Natural and human triggered avalanches likely.

Regions

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

Recent weather conditions have led to slab development at all elevation bands. These slabs are likely to be found sitting on weak layers.

As freezing levels rise over the next few days, expect these slabs to become more sensitive to human triggering and to an increase in natural activity.

Confidence

No Rating

Avalanche Summary

No new avalanches, with good visibility, were observed on a flight from Banff to Lake Louise today. Sunshine saw a natural cornice failure outside the ski area that gouged to ground size 2. Avalanche control on Mount Stephen resulted in size 2 slab avalanches, including one over the ice climb Super Bok.

Bourgeau Left-hand ran sz 2.5 on Thursday with a crown though to be about 50cm deep.

Snowpack Summary

Hard and soft slabs have formed due to recent warming, strong winds, and small snow inputs. These slabs may overlie two weak layers: 1) Facets from the cold snap sit 10 to 30cm deep. 2) Surface hoar or a sun crust have been found in some areas below the facets 30 to 50cm deep.

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

The lower part of the snowpack comprises weak facets and depth hoar.

Weather Summary

Saturday: Trace amounts of snow, SW winds 70kmh decreasing to 40kmh, and freezing levels to 2000m. Little recovery is expected overnight.

Sunday: There will be up to 5cm of snow (possibly rain at lower elevations), 50-70kmh winds from the west, and freezing levels to 2300.

Monday: Freezing levels to 2700m.

For more information, click here.

Terrain and Travel Advice

  • Avoid areas where the snow feels stiff and/or slabby.
  • Avoid shallow snowpack areas, rock outcroppings and steep convex terrain where triggering is most likely.
  • The likelihood of deep persistent slab avalanches will increase with each day of warm weather.

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.