North Columbia

Buried wind slabs that are sitting on facets (weak, sugary snow) may remain reactive to human triggers for longer than what is typical in this region, especially in steep and rocky alpine terrain.

High - The weather pattern is stable

MONDAY NIGHT: Clear / Light, northeasterly winds / Alpine low -18.TUESDAY: Sunny / Light, northeasterly winds / Alpine high -12.WEDNESDAY: Sunny / Light, northeasterly winds / Alpine high -7.THURSDAY: Sunny / Light, northeasterly winds / Alpine high -11.

On Sunday, several human triggered wind slab avalanches up to size 1.5 were reported on north and west aspects in the alpine. Over the past week there have been numerous 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. These layers have created a low likelihood, high consequence scenario that requires discipline and careful terrain selection to manage effectively.

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. These buried wind slabs are sitting on facets (sugary snow) which may cause them to remain reactive to human triggers longer than what is typical for this region.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.