Avalanche Forecast

Archived

Mar 20th, 2025–Mar 21st, 2025

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 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.

New snow will improve riding conditions, but unpredictable avalanches are possible with buried persistent weak layers. Choosing a conservative terrain is a good strategy.

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

Successive snowfalls will bring up to 20 cm of new snow, forming touchy slabs. This overlies wind-affected snow in leeward terrain at upper elevations 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

Thursday Night

Cloudy with 10 to 15 cm of new snow. 30 to 50 km/h southwest ridgetop wind. Treeline temperature -4 °C. Freezing level 1000 m.

Friday

Cloudy with up to 5 cm of new snow. 30 to 40 km/h southwest ridgetop wind. Treeline temperature -2 °C. Freezing level 1200 m.

Saturday

Mix of sun and clouds. 15 to 25 km/h soutwest ridgetop wind. Treeline temperature -2 °C. Freezing level 1200 m.

Sunday

Partly cloudy with isolated flurries. 40 to 60 km/h west ridgetop wind. Treeline temperature +4 °C. Freezing level 2000 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Wind slabs are most reactive during their formation.
Watch for newly formed and reactive wind slabs as you transition into wind-affected terrain.
Be aware of the potential for loose avalanches in steep terrain where snow hasn't formed a slab.
Cornice failures could trigger large and destructive avalanches.

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.