North Columbia

Very large skier triggered persistent slab avalanches continue to be reported in the alpine.

Avoid steep, rocky, and wind-affected areas where triggering slabs is more likely.

On Tuesday, a skier remotely triggered a size 3 persistent slab from 40 m away. It was a steep, rocky, southeast aspect in the alpine.

A couple natural and cornice triggered size 2 storm slabs were also reported on northerly aspects in the alpine.

On Monday, a helicopter remotely triggered a size 2 deep persistent slab on a very steep and rocky northeast aspect in the alpine.

Up to 30 cm of recent snow overlies a crust everywhere except northerly aspects in the alpine where a layer of small surface hoar may be present. Recent snowfall amounts taper with elevation.

Below this is a moist upper snowpack.

Recent avalanche activity has involved multiple persistent weak layers. The most common failure layer is the early March surface hoar, facet, and crust layer, buried 80 to 150 cm deep.

Avalanches have also stepped down to deeper weak layers from February and January, buried 150 to 200 cm deep.

These layers remain a concern for human-triggering and step-down avalanches.

Wednesday Night

Partly cloudy. 10 to 20 km/h northwest ridgetop wind. Treeline temperature -7 °C. Freezing level valley bottom.

Thursday

Mostly sunny. 5 to 10 km/h northwest ridgetop wind. Treeline temperature -4 °C. Freezing level 1600 m.

Friday

Sunny. 5 to 10 km/h northwest ridgetop wind. Treeline temperature 0 °C. Freezing level 2000 m.

Saturday

Sunny. 5 to 10 km/h southwest ridgetop wind. Treeline temperature 4 °C. Freezing level 2500 m.

More details can be found in the Mountain Weather Forecast.

• Cornice failures could trigger large and destructive avalanches.
• Avoid steep, rocky, and wind-affected areas where triggering slabs is more likely.
• Remote triggering is a concern; avoid terrain where triggering overhead slopes is possible.
• Storm slabs in motion may step down to deeply buried weak layers and result in very large avalanches.