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Avalanche Forecast

Archived

Feb 1st, 2023–Feb 2nd, 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 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.

Regions

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

The deep persistent problem remains a problem. Continue to exercise conservative terrain choices.

Confidence

Moderate

Avalanche Summary

Ski hills reported small windslabs with ski cutting and explosives on Wednesday. In the past few days, in Yoho, a deep persistent slab avalanche was observed on Mt. Carnarvon (size 3) and on Mt. Field (size 2.5). These avalanches illustrate the unpredictability of the deep persistent problem that exists in the snowpack.

Snowpack Summary

Moderate to strong west winds have formed wind effect and fresh wind-slabs at alpine and tree-line elevations. The upper snowpack has a weak interface down 20-40 cm on the Jan 4 surface hoar/suncrust layer. The Nov 16 deep persistent layer is down 40-90 cm and continues to produce variable sudden test results. The mid and lower pack is weak in eastern regions and more supportive in western areas.

Weather Summary

Cloudy skies with light flurries along the continental divide on Thursday morning will taper as a surface ridge builds bringing a clearing trend in the afternoon.

Winds will remain strong from the west with alpine temps in the -5 to -10 range on Thursday.

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.
  • In times of uncertainty conservative terrain choices are our best defense.

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.