Avalanche Forecast

Archived

Mar 15th, 2025–Mar 16th, 2025

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

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.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Regions

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

Danger will be HIGH in areas that receive 25 cm or more of new snow.

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

Confidence

Moderate

Avalanche Summary

A widespread region-wide avalanche cycle of natural and human-triggered avalanches occurred over the last few days, with slabs up to size 3 (very large). These avalanches occurred on all aspects and elevations. The majority were storm slabs but a significant amount failed on persistent layers as well.

Looking forward: Avalanche activity is expected to continue through Sunday.

Snowpack Summary

25 to 40 cm of recent snow previously formed widespread storm slabs. An additional 10 to 20 cm is forecast to fall overnight and through Sunday. Southwesterly winds will be building especially reactive slabs on lee north through east facing slopes near ridgetops.There is potential for the new snow to overload deeper persistent layers in the upper to mid snowpack, causing storm slabs to step down. These layers include:

Facets/surface hoar/crust from early March buried 25-50 cm.
Facets/surface hoar/crust from mid-February buried 40-90 cm
Facets/surface hoar/crust from late January buried 80-120 cm.

The rest of the snowpack is well settled with no other layers of concern.

Weather Summary

Saturday Night

Cloudy with 2 to 10 cm of snow. 35 to 45 km/h south ridgetop wind. Treeline temperature -8 °C.

Sunday

Cloudy with 5 to 10 cm of snow. 30 to 40 km/h southwest ridgetop wind. Treeline temperature -4 °C.

Monday

A mix of sun and cloud. 15 to 25 km/h west ridgetop wind. Treeline temperature -5 °C.

Tuesday

A mix of sun and cloud. 15 to 30 km/h northwest ridgetop wind. Treeline temperature -5 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Avoid avalanche terrain during periods of heavy snowfall.
As the storm slab problem worsens, the easy solution is to choose more conservative terrain.
Be aware of the potential for human triggerable storm slabs at lower elevations, even on small features.
Remote triggering is a concern; avoid terrain where triggering overhead slopes is possible.

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.