Regions
Northwest Coastal.
Wind slabs may keep building, even if snowfall amounts are not great.
Confidence
Fair - Timing, track, or intensity of incoming weather system is uncertain
Weather Forecast
Light snow is expected on Friday, Saturday and Sunday (around 5 cm a day). Winds are moderate to strong, mainly from the south. The freezing level should be near 1900 m on Friday, dropping to 300 m on Saturday.
Avalanche Summary
Explosives triggered a size 1.5 wind slab on Wednesday. A skier also recently triggered a size 1 wind slab in the alpine. Explosives control on Sunday triggered several very large avalanches near Stewart, failing at ground or on a deeply buried crust.
Snowpack Summary
Around 1 m of recent storm snow was redistributed by strong and variable winds, creating widespread wind slabs. Operators report settlement and bonding within the storm snow. Older buried surfaces include wind slabs, hard crusts, surface hoar, and/or surface facets. With more snow and wind forecast, new storm slabs are expected to form. The mid-pack is generally well-settled and strong. At the base of the snowpack, weak facets may be found, particularly on shallow alpine slopes in the north of the region. Cornices are large and potentially fragile. Below treeline, the snow appears to be in a spring melt-freeze cycle.
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.