North Columbia

A persistent weak layer that has been most pronounced at lower elevations has created a low likelihood, high consequence scenario that requires discipline and careful terrain selection to manage effectively.

High - The weather pattern is stable

SUNDAY NIGHT: Clear / light, northeasterly winds / Alpine low -19.MONDAY: Sunny / light, northeasterly winds / Alpine high -15.TUESDAY: Sunny / light, northeasterly winds / Alpine high -14.WEDNESDAY: Sunny / light to moderate, easterly winds / Alpine high -9.

Over the past week there have been near daily reports of persistent slab avalanches, some of which were human triggered. They have been large avalanches (size 2-2.5), occurring on a variety of aspects at treeline and below treeline elevations. They are likely failing on the persistent weak layer of surface hoar and/or crusts that were buried mid January.

5-10 cm of recent snow has been redistributed by moderate to strong southwest winds. This snow sits on 10-25 cm of low density snow or older wind slabs that formed on a variety of aspects in many areas. There are two prominent weak layers in the upper snowpack. One was buried at the end of January, and the other was buried mid January. They are approximately 40 and 75 cm below the surface. Both layers consist of a mixture of surface hoar (weak, feathery crystals) and facets (sugary snow), which likely also sit on a sun crust on steep, south facing slopes. These weak layers are most prominent at treeline and below.Very sporadically, failures have occurred near the base of the snowpack in this region, or in neighboring regions. These avalanches have primarily been in steep, rocky, high alpine areas with a shallow snowpack.