Avalanche Forecast

Archived

Mar 22nd, 2025–Mar 23rd, 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 and human triggered avalanches likely.

Treeline

Natural and human triggered avalanches likely.

Below Treeline

Natural avalanches possible, human triggered probable.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches possible, human triggered probable.

Regions

Kootenay Boundary, Bonnington, Grohman, Kootenay Pass, Norns, Rossland, Ymir, Crawford, Moyie, St. Mary, Kokanee, Retallack, Valhalla, Whatshan.

Continued snowfall will keep storm slabs reactive and stress buried weak layers. Conservative terrain choices are crucial.

Confidence

Moderate

Avalanche Summary

Storm slabs have produced many size 1 to 2 avalanches in recent days, including numerous human-triggered slabs in the top 30 cm and larger natural avalanches in alpine terrain.

Two large persistent slab avalanches occurred on Thursday: a skier-triggered size 2 in the Monashees and a natural size 3 in the Selkirks.

Expect continued storm slab activity on Sunday. Persistent slab avalanches will become likely as temperatures warm this week.

Snowpack Summary

Storm slabs will grow on Sunday with 10 to 15 cm of new snow adding to the 15 to 25 cm snow from the previous few days.

Several weak layers in the snowpack are currenlty concerns for triggering persistent slab avalanches:

Facets/surface hoar/crust from early March buried 40 to 70 cm,
Facets/surface hoar/crust from mid-February buried 60 to 100 cm, and
Facets/surface hoar/crust from late January buried 100 to 150 cm.

This complex snowpack combined with dynamic weather makes travel in avalanche terrain dangerous.

Weather Summary

Saturday Night

Mostly cloudy with 0 to 1 cm of snow. 30 km/h southwest ridgetop wind. Treeline temperature -5 °C.

Sunday

Cloudy with increasing snowfall rate and 10 to 15 cm of snow. 40 km/h southwest ridgetop wind. Treeline temperature -5 °C.

Monday

Snow transitioning to rain with 30 to 50 mm in the Monashees and Selkirks and 10 to 20 mm in the Purcells. 60 km/h southwest ridgetop winds. Treeline temperature +2 °C. Freezing level rising to 2400 m.

Tuesday

Cloudy with 10 to 20 mm of rain and then clearing skies in the afternoon. 20 km/h southwest ridgetop wind. Treeline temperature +6 °C. Freezing level 2700 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Use conservative route selection. Choose simple, low angle terrain with no overhead hazard.
Avoid freshly wind-loaded terrain features.
Fresh snow rests on a problematic persistent slab, don't let good riding lure you into complacency.

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.