Avalanche Forecast

Archived

Mar 20th, 2025–Mar 21st, 2025

Alpine

Natural and human triggered avalanches likely.

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 possible, human triggered probable.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Alpine

Natural and human triggered avalanches likely.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Regions

Sea To Sky, Brandywine, Garibaldi, Homathko, Spearhead, Tantalus.

Stormy weather continues !

Avoid avalanche terrain during periods of heavy loading from new snow and wind.

Uncertainty is around how buried persistent weak layers will react to the new load.

Confidence

Moderate

Avalanche Summary

Natural storm slabs were observed on northwest alpine slopes, suspected to have run overnight on Wednesday. Several dry loose were reported from steep terrain at treeline around Whistler.

Avalanche activity will increase during this stormy period and a natural cycle is expected.

Thanks for sharing your observations via the MIN if you are going out into the backcountry.

Snowpack Summary

Another 15 to 30 cm of new snow is expected by Friday afternoon, forming touchy storm slabs. This overlies wind-affected snow in lee terrain at upper elevations and moist, heavy snow or a melt-freeze crust on southerly slopes, especially at lower elevations. This sits over 120 to 175 cm of settling storm snow from the past week.

Under it, a weak layer formed in early March that consists of a crust on all aspects except high north-facing slopes and facets or surface hoar in some areas. Weak layers formed in mid-February and late January are now buried 150 to 250 cm deep.

Below this, the snowpack is well-settled and strong.

Weather Summary

Thursday Night

Cloudy with 15 to 30 cm of new snow. 50 to 70 km/h south ridgetop wind. Treeline temperature -4 °C. Freezing level 1000 m.

Friday

Cloudy with 10 to 15 cm of new snow. 20 to 40 km/h southwest ridgetop wind. Treeline temperature -4 °C. Freezing level 1000 m.

Saturday

Cloudy with isolated flurries. 20 to 30 km/h west ridgetop wind. Treeline temperature -2 °C. Freezing level 1200 m.

Sunday

Cloudy with 20 to 30 cm of new snow. 50 to 70 km/h south ridgetop wind. Treeline temperature +2 °C. Freezing level 1600 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Avoid areas with overhead hazard.
Storm slabs in motion may step down to deeper layers resulting in large avalanches.
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

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.