South Columbia

New snow and wind will drive the avalanche danger throughout the forecast period. Watch for new wind slabs at treeline and in the alpine.

Moderate - Intensity of incoming weather systems is uncertain

Tuesday night: 8-15cm of new snow / Extreme westerly winds / Alpine temperatures of about -15Wednesday: 3-5cm of new snow / Strong westerly winds / Alpine temperatures of about -16Thursday: 5-10cm of new snow / Strong southerly winds / Alpine temperatures of about -8Friday: 3-8cm of new snow / Light and variable winds / Alpine temperatures of about -8

On Sunday, small avalanches in the new snow were reported including natural and skier triggered size 1 wind slabs on a variety of aspects. Sluffing in steep terrain was widespread. A few size 2 natural avalanches were also reported in alpine terrain, potentially releasing on the mid-February interface 30-40 cm deep. Looking forward, new snow and extreme winds on Tuesday night are expected to promote new wind slab activity at treeline and in the alpine.

By Wednesday morning, new snow and extreme winds are expected to have formed fresh wind slabs at treeline and in the alpine. About 30-50cm below the surface you'll likely find the mid-February interface which is composed of a thick rain crust up to about 1800 m, sun crusts on steep solar aspects, and spotty surface hoar on shaded aspects. This layer could develop into a persistent slab problem once the snow above it settles into a stiffer slab. The mid and lower snowpack are generally well settled and stable.