Northwest Coastal

Wednesday will see a small weather break in a powerful, multi-day storm. It is a good time to remain extremely cautious with all the new snow and rain and give the snowpack time to strengthen.

Moderate - Timing, track, or intensity of incoming weather system is uncertain

TUESDAY NIGHT: Cloudy with light rainfall at lower elevations and snowfall above, accumulation 30 to 40 cm, strong southwest winds, alpine temperature 1 C, freezing level 1600 m.WEDNESDAY: Mix of sun and cloud, moderate to strong west winds, alpine temperature -3 C, freezing level 900 m.THURSDAY: Cloudy with snowfall, accumulation 20 to 40 cm, strong south winds, alpine temperature -1 C, freezing level 700 m.FRIDAY: Mostly cloudy with light snowfall, accumulation 5 cm, strong west winds, alpine temperature -4 C, freezing level 500 m.

It is expected that a natural storm cycle occurred on Monday night into Tuesday with the substantial amount of new snowfall and rain, particularly in the south of the region.On Sunday, a skier remotely triggered a large (size 3) avalanche in the backcountry near Shames. See the MIN report here, which describes it and there are also some photos floating around social media. Although unclear, it appears that the likely culprit was the mid-December weak surface hoar layer described in the snowpack summary.

Up to 50 cm of snow fell on Tuesday, mixed with rain below about 1500 m. Another 40 cm is possible Tuesday night above 1500 m. The storm came with strong southwest winds, which likely produced wind slabs in lee terrain features at high elevations. Below 1500 m, expect soggy snow and a thick melt-freeze crust once it is cold enough. This new snow along with other recent storm snow overlies a weak layer of feathery surface hoar that was buried around December 22. Expect to find this layer about 80 to 120 cm deep.Lower in the snowpack around 150 to 200 cm deep, a weak layer from mid-December exists. It is likely that this layer was the culprit of a large, remotely-triggered avalanche on December 30 near Terrace. There are other reports indicating that this layer is still well-developed in the south of the region and it could be triggered by humans in shallow snowpack areas. Shallower storm slabs could step down to this layer and produce very large avalanches. For the north of the region, such as Ningunsaw, this layer was most prevalent between 1100 and 1300 m.