North Columbia

It's starting to sound like a broken record, but a persistent slab problem still exists. Although the likelihood of triggering the persistent slab has reduced, the consequences of doing so would be high.

High - The weather pattern is stable

SUNDAY: Sunny with cloudy periods / light northeast wind / alpine temperature -15MONDAY: A mix of sun and cloud / light northeast wind / alpine temperature -14TUESDAY: Mostly sunny / light to moderate east wind / alpine temperature -15

On Thursday, there were two reports of human triggered persistent slab avalanches. They were both size 2 and occurred on north and northeast aspects at treeline and below treeline. These avalanches failed on a persistent weak layer that was buried in mid January.On Wednesday, several natural loose and wind slab avalanches to size 2 were reported. There were also reports of 3 persistent slab avalanches between size 2-2.5. These occurred on south and southeast aspects at alpine and treeline elevations. Two were natural and one was triggered remotely (from a distance) by a person. Over the past week there have been near daily reports of persistent slab avalanches, some of which are human triggered. They have been in the size 2-3 range and are likely failing on the persistent weak layer that was buried mid January.

5-10 cm of snow falling Thursday and Friday has been redistributed by moderate to strong southwest winds. This 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 mix of surface hoar (feathery crystals) and facets (sugary snow), which likely also sit on a sun crust on south facing slopes. These weak layers are most prominent at treeline and below, though south facing slopes at any elevation are suspect as well.Very sporadically, failures have occurred near the base of the snowpack in this region, or in neighboring regions. These releases have almost all been from high alpine areas, possibly triggered close to rocky features.