Regions
Northwest Coastal.
Up to 40cm of new snow has been blown by strong winds into much deeper deposits, and large human-triggered avalanches remain a concern. Conservative terrain selection remains critical.
Confidence
Fair - Due to the number of field observations
Weather Forecast
Mainly overcast skies, strong southwest winds and very light snowfall are expected on Saturday. On Sunday and Monday a Pacific low will make landfall bringing heavy snowfall (up to 40cm) with the highest accumulations forecast for the south of the region. Winds with the storm should be strong to extreme from the southwest. Freezing levels should hover around 1000m on Saturday, spiking briefly to 1500m on Sunday, and then falling back to about 1000m on Monday
Avalanche Summary
At the time of writing, observations were extremely limited, but I expect a large, widespread natural cycle occurred in response to snow and wind-loading over the past few days. I would expect ongoing potential for human triggering of the new snow due to underlying weak surfaces. Looking forward, I would expect natural storm slab activity to ramp up again with new snow and wind forecast for Sunday and Monday.
Snowpack Summary
By Friday morning up to 40cm of new snow had fallen with the highest accumulations occurring in the southwest of the region. The new snow, moderate temperatures and strong southwest winds have likely built dense wind slabs on lee features, and storm slabs in more sheltered spots. The new snow overlies a variety of interfaces including old hard wind slabs, hard crusts, surface hoar, and/or surface facets. At the base of the snowpack, weak facets may be found, particularly on alpine slopes in the north of the region. Keep an eye out for cornices that could fail.
Problems
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.