South Columbia

Heavy snowfall, warm temperatures, and wind are expected to build reactive storm slabs which may overlie a weak layer of surface hoar, facetted snow, or a slick crust.

Choose low-consequence and well-supported terrain with no overhead hazard.

A series of frontal systems impacting the coast will bring continued snowfall throughout the week.

Monday Overnight: Overcast to obscured skies, with rain at lower elevations and snowfall above ~1300 m, 10-20 cm of accumulation. Moderate to strong southwest winds at ridgetop. Freezing level around 1500 m.

Tuesday: Continued snowfall above ~1300 m, 5-20 cm of accumulation, rain at lower elevations. Light to moderate southwesterly winds. Freezing level around 1600 m.

Wednesday: Mix of sun and cloud with some with light precipitation, 0-5 cm of new snow accumulation above 1500 m. Light to moderate westerly winds. Freezing level around 1500 m.

Thursday: Mainly cloudy with light precipitation, 0-5 cm of new snow accumulation above 1500 m. Light to moderate westerly winds. Freezing level around 1500 m.

Numerous natural and skier-triggered storm slab avalanches up to size 2 were reported over the weekend. The storm slabs were most reactive were they were sitting on a sun crust or a weak layer of surface hoar.

A large skier-triggered avalanche was reported on Sunday to the west of the Monashees. This avalanche occurred on a convex roll below treeline and is suspected to have failed on a persistent weak layer in the upper snowpack. The full report can be seen here.

30-50 cm of recent snow and moderate southwest winds has formed storm slabs that have been most reactive in wind-affected terrain; especially where slabs are sitting on a weak layer of surface hoar or a sun crust.

This new snow is sitting on various surfaces, including hard wind-affected snow, sun crusts on southerly slopes, and surface hoar on shady or sheltered slopes. 

The late February persistent weak layer combination of crust, facets and surface hoar is down 40-50 cm. Reports suggest this layer is becoming less reactive in most areas but remains a concern with warming temperatures and additional load on the snowpack.

Two additional persistent weak layers from late January and mid-February are down 80-120 cm. They both consist of surface hoar and/or melt-freeze crusts. Recent trends indicate these layers are gaining strength. 

The most recent human-triggered avalanches on these layers were in the southern Selkirks around the Valhalla, Kokanee, and Goat Ranges over the weekend of March 5-6th. 

• Conservative terrain selection is critical, choose only well supported, low consequence lines.
• Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.
• Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
• Be especially cautious as you transition into wind affected terrain.
• Avoid freshly wind loaded features, especially near ridge crests, roll-overs and in steep terrain.