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Avalanche Forecast

Archived

Feb 15th, 2023–Feb 16th, 2023

Alpine
Natural avalanches unlikely, human triggered possible.
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

South Coast Inland, Birkenhead, Duffey, South Chilcotin, Stein, Taseko.

Avalanches are possible in wind-loaded areas at treeline and above. Carefully evaluate wind loading as you move through terrain and investigate the bond of wind slabs to the crust below them before committing to a slope.

Avoid shallow rocky areas where the snowpack transition from thick to thin and triggering deep persistent layers is more likely.

Confidence

Moderate

Avalanche Summary

On Tuesday, several large natural deep persistent slab avalanches were reported near South Chilcotin Mountains Provincial Park and the Birkenhead area. The avalanches were up to size 3 and were likely triggered by cornices or wind. See this MIN for photos of a few of the avalanches.

Numerous small loose dry avalanches were reported to size 1.5 on all aspects. A skier accidental size 1 wind slab avalanche was reported in northeast facing alpine terrain.

On Monday afternoon, search and rescue technicians responded to a fatal avalanche incident north of the Sea to Sky region. The avalanche is believed to have occurred on Saturday and was initiated in a shallow rocky area. See the MIN for more details.

A skier remote triggered, size 2 avalanche was reported on a cross-loaded morainal feature. The group reported the avalanche as a soft wind slab over a crust. The slope fractured 30 m above the group. See the MIN for more information.

Snowpack Summary

10-20 cm of recent storm snow is being redistributed by variable winds. This overlies wind-affected surfaces at higher elevations and a crust at lower elevations. On steep solar slopes, a new sun crust has formed on the surface.

A melt-freeze crust from late January is found down 60-80 cm. At the moment this layer appears to be gaining strength though in isolated areas small facets are still found surrounding the crust.

There is a widespread weak layer of large sugary of facets at the bottom of the snowpack. This layer has recently resulted in a handful of large destructive avalanches. These avalanches seem to be concentrated in the northern half of the region however the layer is found throughout. Snowpack depths around treeline range between 150 to 250 cm.

Weather Summary

Wednesday Night

Cloudy with isolated flurries, trace accumulation. Winds west 10 km/h gusting 40 km/h. Treeline temperature -10 °C. Freezing levels drop to the valley bottom.

Thursday

Mainly cloudy with isolated flurries, 1-3 cm accumulation. Winds southwest 25 km/h gusting to 40 km/h. Treeline temperature -8 °C. Freezing level 800 m.

Overnight flurries bring 2-10 cm accumulation.

Friday

Cloudy with sunny periods and isolated flurries, trace accumulation. Winds west 25 km/h. Treeline temperature -8 °C. Freezing level 1000 m.

Saturday

Cloudy with isolated flurries, trace accumulation. Winds west 25 km/h. Treeline temperature -5 °C. Freezing level 1200 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Pay attention to the wind, once it starts to blow fresh sensitive wind slabs are likely to form.
  • Recent wind has varied in direction so watch for wind slabs on all aspects.
  • Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
  • In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.

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.