Avalanche Forecast

Archived

Mar 18th, 2025–Mar 19th, 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, 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

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

Fresh wind slabs will build throughout the day. Be mindful of the potential for a step-down avalanche with the persistent slab problem, creating larger-than-expected avalanches.

Confidence

Moderate

Avalanche Summary

Numerous natural wind slabs (size 1.5) were reported from north alpine lee and cross-loaded features. Skier's traffic produced wind slab avalanches (size 1.5), with good propagation along ridge crests at treeline.

On Monday, fast-running sluffs were easily triggered by riders on steep northerly slopes, producing small loose dry avalanches throughout the region.

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

Snowpack Summary

10 to 20 cm of recent snow exists, with deeper deposits of wind-transported snow in lee terrain. Southerly slopes have been sun-affected and the surface snow is moist and/or heavy snow. 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

Tuesday Night

Cloudy with isolated flurries. 30 to 40 km/h south ridgetop wind. Treeline temperature -6 °C. Freezing level 800 m.

Wednesday

Cloudy with 10 to 15 cm of new snow. 40 to 50 km/h southeast ridgetop wind. Treeline temperature -2 °C. Freezing level 1200 m.

Thursday

Cloudy with 10 to 15 cm of new snow. 30 to 50 km/h south ridgetop wind. Treeline temperature -2 °C. Freezing level 1200 m.

Friday

Cloudy with 10 to 15 cm of new snow. 30 to 40 km/h south ridgetop wind. Treeline temperature -2 °C. Freezing level 1200 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Wind slabs are most reactive during their formation.
Be careful as you transition into wind-affected terrain.
If triggered, wind slabs avalanches may step down to deeper layers resulting in larger 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

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.