North Columbia

Large persistent slab avalanches continue to be reported, primarily on northerly aspects in the alpine.

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

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

A couple natural and skier triggered wind slabs were reported on northerly aspects in the alpine.

On Sunday, a naturally triggered size 2.5 persistent slab was reported on a northerly aspect in the alpine.

10 to 20 cm of snow overlies a wet, rain-soaked upper snowpack. Expect a surface crust to form at night on most terrain, except possibly on high north alpine slopes.

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 70 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.

Tuesday Night

Mostly cloudy with flurries, 0 to 15 cm of snow. 10 to 20 km/h west ridgetop wind. Treeline temperature -5 °C. Freezing level 800 m.

Wednesday

Mostly cloudy with flurries, 0 to 10 cm snow above 1300 m, rain below. 10 to 20 km/h west ridgetop wind. Treeline temperature -3 °C. Freezing level 1700 m.

Thursday

Mostly sunny. 10 to 20 km/h north ridgetop wind. Treeline temperature -5 °C. Freezing level 1500 m.

Friday

Sunny. 5 to 10 km/h northwest ridgetop wind. Treeline temperature -1 °C. Freezing level 1900 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.
• Triggering deep layers is more likely if the snow surface didn't freeze overnight.
• Use small, low consequence slopes to test the bond of the new snow.