Watch for the formation of fresh wind slabs in exposed terrain as southwest wind picks up ahead of the next storm on Thursday. Snow amounts appear modest for Thursday, but watch for hazard to increase through the day, especially in areas that receive more than 20 cm of new snow.
Time and relatively cool temps are likely tempering reactivity of wind slabs formed over the weekend, but a fresh round of wind slabs will likely form Thursday as southwest wind picks up ahead of the next storm.
The early December crust can be found down 80 to 150 cm below the surface. While activity on this interface has really tapered off, it makes it difficult to have much confidence in stepping out into bigger terrain as avalanches failing on this layer have the potential to be very large and destructive.
A storm impacting the region offers a nice refresh of cold snow accompanied by strong wind largely out of the south.
WEDNESDAY NIGHT: Freezing level at valley bottom, trace of snow possible, light variable wind.
THURSDAY: Overcast, freezing level at valley bottom, moderate wind largely out of the southwest, snow beginning in the morning, 2 to 8 cm expected during the day with another 5 to 15 cm expected Thursday night.
FRIDAY: Overcast, freezing level at valley bottom, strong west/southwest wind, 5 to 15 cm of snow possible.
SATURDAY: Broken cloud cover, freezing level at valley bottom, moderate west wind, 1 to 5 cm of snow possible.
Avalanche activity in the storm snow was diminished Tuesday, but there were still some natural avalanches to size 1.5 that were most prevalent in wind loaded upper elevation terrain features.
Lots of natural storm slab and loose dry avalanche activity to size 2 was observed Monday on all aspects.
Over the last week in the North Columbias, reported avalanche activity on the early December crust/facet interface has been confined to a pair of isolated avalanches in complex northeast facing alpine terrain which were triggered with explosive control work. The size 3 avalanches had crowns over a meter in depth.
The weekend storm produced 20 to 60 cm of storm snow accompanied by wind that was quite variable, but mainly out of the south. Early reports from folks exploring in the alpine report that there was less wind loading than expected.
We're actively monitoring the early December crust. In some places it's scoured and on the surface, while in wind loaded terrain features it can be found as deep as 150 cm below the surface. It consists of faceted grains above a bulletproof crust formed by the Atmospheric Rivers of early December. There has been isolated avalanche activity on this crust in the last week that seems to be confined to complex alpine terrain.
