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Avalanche Forecast

Archived

Jan 4th, 2025–Jan 5th, 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.

West winds are forecast to increase into the moderate range in the alpine late in the day Saturday. If this happens, expect these winds to redistribute the recent 10-20cm of storm snow into slabs near ridge crest.

Confidence

Moderate

Avalanche Summary

The majority of the natural activity following the most recent snowfall has been reported as small loose dry out of very steep terrain on Highway 93N and 93S.

Evidence of a large deep avalanche off of Mount Lefroy North East face was observed on Jan 3rd and is believed to be 24-48 hours old.

The ski areas continue to deal with small, remnant wind slabs up to sz 1.5.

Sunshine had another size 1.5 slab as a result of explosives in a shallow area on the deep persistent weak layer.

Snowpack Summary

Up to 25cm of low-density recent snow overlies a weak, faceted, mid and lower snowpack. Very weak depth hoar and facets associated with remnant crusts are found near the ground. 60-100cm of snow at treeline elevations.

Weather Summary

A trough will push east towards the region Saturday evening before the competing high pressure over the prairies pushes back west Sunday.

Winds will increase into the moderate range late Saturday with trace amounts of new snow overnight before winds shift northwest to bring clearing and a bit of cooling through Sunday.

Terrain and Travel Advice

  • Avoid thin areas like rocky outcrops where you're most likely to trigger avalanches on deep weak layers.
  • Pay attention to the wind; once it starts to blow, sensitive wind slabs are likely to form.

Problems

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.

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.