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Avalanche Forecast

Archived

Jan 23rd, 2023–Jan 24th, 2023

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

Kootenay Boundary, Bonnington, Kootenay Pass, Norns, Rossland, South Okanagan, Ymir, Moyie, St. Mary.

The stable weather pattern is having little effect on our buried layers causing them to remain with us for the time being.

Seek out low-angle terrain that has a deep snowpack to find the best and safest riding.

Confidence

Moderate

Avalanche Summary

Sunday's avalanche activity saw size one and size two avalanches. These were from wind slabs and persistent slabs. They were triggered naturally and by skiers, accidentally and with ski cuts.

New weak layers are beginning to develop in the upper snowpack while our buried weak layers still pose a threat Under the right circumstances, riders can trigger these layers. Heavier loads like those created by smaller avalanches will trigger these deeper layers as well.

Snowpack Summary

At higher elevations, wind slabs are beginning to form from west and southwest winds. In sheltered areas surface hoar growth has been reported. The top 30 to 50 cm of snow contains a wide variety of layers that include, crusts, surface hoar, and facets. These layers have not yet produced widespread avalanches however, they are important to keep in mind as they vary with aspect and elevation as they still pose a hazard depending on your terrain choices.

Layers that are presently a concern include a surface hoar layer developed in early January and a melt-freeze crust from late December that is now down approximately 70 cm. These layers have created our persistent slab problem. The deep persistent slab problem stems from a weak layer created in mid-November and it is now buried 100 to 190 cm deep. These layers are a major concern and if triggered they can result in large avalanches.

Thank you for inputting your snowpack observations in the MIN. For more information on the state of the snowpack, click HERE.

Weather Summary

Monday Night

Cloudy, no accumulation, wind northwest 20 km/h, treeline temperatures around -6 C.

Tuesday

Cloudy with some sun, up to 4 cm accumulation in the western portion of the region, wind northwest 20 to 30 km/h, treeline temperatures -6 C freezing level reaching 1000 m.

Wednesday

Mostly sunny, no accumulation, wind northwest 20 to 30 km/h, treeline temperatures -5 C.

Thursday

A mix of sun and cloud, trace accumulation, wind west 35 km/h, treeline temperature -5 to 0 C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Be aware of the potential for surprisingly large avalanches due to deeply buried weak layers.
  • Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
  • In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.
  • Recent wind has varied in direction so watch for wind slabs on all aspects.

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.