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Avalanche Forecast

Archived

Jan 31st, 2025–Feb 1st, 2025

Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches possible, human triggered probable.
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.

A combination of new snow (20 cm+ by Sunday) and moderate to strong winds will cause the avalanche danger to increase. We have some uncertainty on how the deep persistent avalanche problem will react to this new load.

Confidence

Moderate

Avalanche Summary

No new slab avalanches were observed or reported on Friday. Local ski hills have primarily reported loose dry avalanche activity, typically triggered by ski cuts.

Snowpack Summary

5-20 cm of new snow and strong winds will create surface slabs that bond poorly to the underlying snow. The layer being buried on Jan 30 is a mix of crust, surface hoar and facets - none of which will bond well to the new snow. The snowpack is generally weak, with an old crust and depth hoar at the base, so any avalanches starting in the surface layers may step down to the ground and become larger.

Weather Summary

A westerly flow will continue to bring precipitation to the forecast region over the weekend, with an additional 10 to 20 cm of snow expected by Sunday. Moderate to strong winds will accompany the new snow at ridge crests. Temperatures will gradually cool as an arctic air mass moves in, and by early next week, temperatures will plummet, with nighttime lows approaching -30°C.

Terrain and Travel Advice

  • Storm slab size and sensitivity to triggering will likely increase through the day.

Problems

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.

Loose Dry

Loose Dry avalanches are the release of dry unconsolidated snow and typically occur within layers of soft snow near the surface of the snowpack. These avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs.

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.