Regions
Northwest Coastal.
Avalanche hazard will likely be on the rise as forecast storm snow begins to stack up.
Confidence
Fair - Intensity of incoming weather systems is uncertain on Saturday
Weather Forecast
5-15 cm of snow is expected for Saturday, another 10-20 cm by Sunday morning, 5-15 cm throughout the day on Sunday and 5-20 cm overnight into the day Monday, with the heaviest snow amounts expected for the southern coastal parts of the region. Freezing levels are expected to remain around 1200 m for the forecast period, and strong southwesterly alpine winds are expected to accompany the most intense snowfall periods.
Avalanche Summary
Several natural storm slab avalanches up to Size 3 were reported on Thursday. Many of them occurred on Wednesday. Storm and wind slabs were also highly reactive to human triggers on Thursday with several skier-controlled avalanches up to Size 1.5 running on a buried crust.
Snowpack Summary
30-50 cm of recent heavy storm snow and thicker wind slabs are poorly bonded to crusts and other slippery previous snow surfaces. A hard crust with weak facets, buried early March, may be lurking over a metre down. This condition seems more specific to the northern parts of the region. Although reports suggest this persistent weakness has gained significant strength, I'd be wary of the possibility of isolated large avalanches on steep, unsupported slopes, especially if temperatures increase, or if solar radiation is strong. On sun-exposed slopes and at lower elevations, the snowpack is likely in a spring melt-freeze cycle. 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.
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.