South Columbia

Extra caution is required on Tuesday as freezing levels climb to mountain top elevation and the snowpack sees major warming for the first time this winter. Avoid steep sun exposed slopes during the heat of the afternoon.

Moderate -

On Tuesday, sunny conditions are expected with light alpine wind from the southwest in the morning becoming moderate to strong in the afternoon. Freezing levels are forecast to reach around 2800 m with a temperature inversion keeping the valleys colder than the alpine. A layer of valley fog may also develop. On Wednesday, mostly cloudy conditions are expected with light rain beginning in the afternoon. Alpine wind is forecast to be moderate to strong from the southwest and freezing levels are expected to remain at around 2500 m. Light rain is forecast to continue Wednesday night and Thursday. 5-10 mm of precipitation is currently forecast between Wednesday afternoon and Thursday evening. Freezing levels are forecast to drop to around 2000 m on Thursday.

On Sunday, a few natural wind slabs were observed in the alpine. A MIN report describes a remotely triggered size 3 avalanche on London Ridge. Click here for more details. A skier also triggered a size 1 storm slab on a south aspect at 2000 m elevation. A few natural and explosive triggered cornice releases were also reported but none of these triggered slabs on the slopes below. On Saturday, natural loose dry avalanches up to size 1.5 were reported as well as a couple skier triggered size 1-2 storm slab avalanches. On Thursday through Friday night, widespread natural and human-triggered storm slab avalanches up to Size 3 were reported throughout the region. On Tuesday, storm slabs overlying a weak layer are expected to remain reactive to human triggering. Extra caution is recommended during the heat of the afternoon, especially on sun exposed slopes. This will become increasingly important through the week as freezing levels remain very high. We have entered the first period of substantial warming following months of sustained cold conditions. Any weaknesses lingering in the snowpack will be tested in the coming days.

The storm snow from Thursday and Friday is settling quickly due to the recent mild temperatures. The snow surface is expected to have undergoing some melting on Monday afternoon on sun exposed slopes. Recent strong winds from the south and west had redistributed the recent storm snow in exposed terrain forming touchy wind slabs. The early February weak layer is typically down 50-80 cm and includes a sun crust on steep sun-exposed slopes, faceted snow, as well as surface hoar on sheltered open slopes. The mid and lower snowpack are generally well settled and stable in deeper snowpack areas but may be faceted and weaker in shallower areas.