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Avalanche Forecast

Archived

Jan 30th, 2023–Jan 31st, 2023

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 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

Kakwa, Pine Pass, Tumbler.

Assess for wind slabs in steep terrain and remember that a small avalanche could step down to deeper weak layers.

Confidence

Moderate

Avalanche Summary

No new avalanches were observed on Sunday. Many wind slab avalanches were triggered by riders and naturally on Saturday. They occurred on all aspects.

Looking forward, riders may trigger wind slab avalanches in wind-exposed terrain as we receive new snow and strong wind. Smaller avalanches could step down to the facets near the base of the snowpack, producing very large avalanches. See more on the potential of triggering deeper weak layers Forecasters' Blog.

Please continue to send in your observations through the MIN.

Snowpack Summary

New snow and strong wind may form new wind slabs in lee terrain features in wind-exposed terrain. The snow will rest on previously wind-affected snow. A melt-freeze crust is found near the snow surface on sun-exposed slopes and everywhere below 1600 m.

Several crust/facet/surface hoar layers exist in the upper and middle portions of the snowpack. Recent observations suggest these layers are not as concerning as in neighbouring regions.

The most concerning layer is at the base of the snowpack from large and weak facets formed in November. This layer is widespread and most likely problematic in steep, rocky alpine terrain.

Weather Summary

Monday Night

Cloudy with snowfall, accumulation 5 to 10 cm with local enhancements possible, 20 to 40 km/h west wind, treeline temperature -12 °C.

Tuesday

Cloudy with snowfall, accumulation 5 to 10 cm with local enhancements possible, 30 to 50 km/h west wind, treeline temperature -12 °C.

Wednesday

Cloudy with snowfall, accumulation 5 to 10 cm, 20 km/h southwest wind, treeline temperature -15 °C.

Thursday

Cloudy with snowfall, accumulation 5 to 10 cm, 30 km/h southwest wind, treeline temperature -9 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
  • Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.
  • Uncertainty is best managed through conservative terrain choices at this time.

Problems

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.

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.