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Avalanche Forecast

Archived

Nov 28th, 2022–Nov 29th, 2022

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

Natural avalanche activity has tapered off, but the potential for human triggered avalanches remains, with lots of uncertainty around the likelihood of triggering slabs sitting over the weak basal facets. Treat steep terrain with extra caution.

The cold temperatures pose another hazard so dress warm and be prepared to stay out longer than expected.

Confidence

Moderate

Avalanche Summary

One size 2 skier triggered avalanche on the basal facets was observed near Lake Louise Monday afternoon. A couple size 2-2+ Na avalanches that failed during the recent storm were also observed on the 93N. They also appear to have failed on the basal facets.

Snowpack Summary

Over the past three days, up to 20 cm of storm snow has accumulated at treeline. The storm snow arrived with strong SW/W winds creating fresh wind slabs in the alpine and open treeline locations.

The snowpack below this recent snow is a mix of weak facets, spotty surface hoar, or sun crust on steep south aspects. 40-80 cm of total snow exists at treeline throughout the region, with up to 120 cm in loaded alpine features.

Weather Summary

Temperatures stay cold with alpine highs of -20°C as an arctic ridge settles into the region. Alpine winds remain light from the W/SW on Tuesday. Skies will become cloudy with trace amounts of new snow expected as an upper trough moves through the area.

https://avalanche.ca/weather/forecast

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
  • Fresh snow rests on a problematic persistent slab, don't let good riding lure you into complacency.
  • Watch for wind-loaded pockets especially around ridgecrest and in extreme terrain.

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.

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.