South Columbia

The persistent slab problem is best managed with patience and conservative terrain choices. Read more in the new forecaster blog here.

High - Due to the number and quality of field observations.

SUNDAY NIGHT: Isolated flurries with localized accumulations of 2-5 cm, light wind from the southwest, alpine temperatures drop to -8°c. MONDAY: Mostly cloudy with a few sunny breaks, light wind, alpine high temperatures around -8°c. TUESDAY: Mix of sun and cloud, light wind, alpine high temperatures around -10°c. WEDNESDAY: Mostly cloudy, light wind, alpine high temperatures around -10°c.

Preliminary reports from Sunday indicate the most recent 20 cm of new snow was reactive to skiers on steep and convex features. No significant avalanche activity was reported on Saturday, as natural and human triggered activity has started to tapered off. However, as recent as Friday, large (size 2-3) persistent slab avalanches were occurring naturally. There have also been a few notable persistent slab avalanches remotely triggered from skiers on adjacent slopes. Most recently, a few large (size 2-2.5) avalanches on north-facing slopes at treeline elevations were remotely triggered by skiers in the Selkirks on Wednesday.

Recent wind from the southwest has formed wind slabs in the alpine and around treeline. A week of stormy weather has deposited 50-100 cm of snow above a weak layer of facets (sugary snow), surface hoar (feathery crystals), and a sun crust (on south aspects) that formed during the dry spell in early December. This layer has been responsible for large persistent slab avalanches over the past week, particularly on northeast facing slopes above 1900 m and on south-facing slopes in the alpine. The potential exists for smaller avalanches to step down and trigger this layer, resulting in very large avalanches. Another weak layer from mid-November is now buried up to 120 cm, but has been less active recently. At the base of the snowpack is a crust that formed in late October.