South Columbia

The gradient in forecast snowfall for Saturday's storm greatly favours the north of the region and the Monashees. Expect less new snow toward the south and east, and CONSIDERABLE danger in areas that see 25 cm or less new snow.

Moderate - Forecast snowfall amounts are uncertain

Friday night: Cloudy with increasing snowfall bringing 10-15 cm of new snow with a focus in the north and the Monashees. Moderate to strong southwest winds, increasing overnight.Saturday: Cloudy with continuing snowfall bringing another 15-30 cm of new snow with a focus in the Monashees. Moderate southwest winds increasing to strong over the day. Alpine high temperatures around -5, with freezing levels rising to a possible 1500 metres.Sunday: Mainly cloudy with isolated flurries and a trace of new snow. Moderate northwest winds decreasing over the day. Alpine high temperatures around -10.Monday: A mix of sun and cloud. Light northwest winds. Alpine high temperatures around -12.

Avalanche activity has diminished over the last few days. On Wednesday, reported activity was limited to two events. One was a large (size 2) persistent slab avalanche that was triggered by a skier in the far southwest of the region as they entered an open glade below a treed ridge on a southeast aspect at 2200 metres. The second was a small wind slab on a west facing aspect at ridgecrest. Otherwise, mainly minor skier and explosives-triggered sluffing continues to show in recent reports. On Monday a few old size 2 natural avalanches were observed on south facing features between 1600 and 2300 m. The avalanche at 1600 m was notable as it was below treeline.Looking forward, increasing snowfall, wind, and freezing levels are setting up conditions ideal for the formation of storm slabs and natural avalanche activity. Although the likelihood of storm slabs 'stepping down' to deeper persistent slab problems is in question, travel plans should account for very large avalanches as the possible result.

A building storm is now depositing new snow on the surface. Below the new snow, 10 to 20 cm of older low density snow sits above old wind slabs in the alpine, and in some isolated areas above small surface hoar (feathery crystals).A weak layer that formed during the dry spell in early December is now 60 to 120 cm deep. The layer is composed of facets, surface hoar, and a sun crust on steep south-facing slopes. This layer was previously responsible for large persistent slab avalanches, but activity has greatly diminished over the last week. Saturday's storm may breathe some life into it, the places of greatest concern will be north and east facing slopes between 1900-2300 m and steep south-facing slopes in the alpine.The lower snowpack is generally strong and settled, with a crust that formed in late October near the bottom of the snowpack.