Avalanche Forecast

Archived

Mar 19th, 2025–Mar 20th, 2025

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

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

Fresh wind slabs will develop with the new snow and wind.

The potential for a step-down avalanche remains with the persistent slab problem.

Confidence

Moderate

Avalanche Summary

On Monday, two very large persistent slabs were remotely triggered by skiers and a snowcat in the Birkenhead area. They occured on west and east alpine slopes and ran full path. Crowns were 75 to 100 cm and one of them stepped down to the mid-February week layer.

Debris from natural and human-triggered avalanches (such as cornice falls, wind, and storm slabs) from the stormy weekend continues to be reported in the region (up to size 3).

Snowpack Summary

Up to 10 cm of new snow and strong wind is expected by Thursday afternoon, forming small but touchy wind slabs. This overlies wind-affected snow in lee terrain at upper and a melt-freeze crust on southerly slopes up to 2000 m. This sits over 80 to 150 cm of settling storm snow from the past week.

The early March weak layer of facets or surface hoar on a crust is now down 100 to 150 cm and present on all aspects except high north-facing slopes. Very large avalanches (size 3 to 3.5) were reported on this layer in the past week.

Weak layers formed in mid-February and late-January are now buried 110 to 190 cm deep.

Weather Summary

Wednesday Night

Cloudy with up to 5 cm of new snow. 40 to 60 km/h south ridgetop wind. Treeline temperature -6 °C. Freezing level 800 m.

Thursday

Cloudy with up to 5 cm of new snow. 30 to 50 km/h southwest ridgetop wind. Treeline temperature -2 °C. Freezing level 1200 m.

Friday

Cloudy with 10 to 20 cm of new snow with convective flurries. 30 to 40 km/h southwest ridgetop wind. Treeline temperature -2 °C. Freezing level 1200 m.

Saturday

Cloudy with isolated flurries. 15 to 25 km/h west ridgetop wind. Treeline temperature -2 °C. Freezing level 1200 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Be alert to conditions that change with elevation, aspect, and exposure to wind.
If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
Cornice failures could trigger large and destructive avalanches.
Be aware of the potential for loose avalanches in steep terrain where snow hasn't formed a slab.

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.

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.