Regions
Northwest Coastal.
Strong winds and heavy snowfall are expected to increase the Danger to HIGH by morning.
Confidence
Fair - Timing, track, or intensity of incoming weather system is uncertain
Weather Forecast
Overnight and Thursday: A strong pulse of Pacific moisture will continue to bring snow overnight, with 20-30 cm accumulating by morning. Snowfall should moderate during the day, another 10-15 cm is forecast. Strong Southwest winds overnight should gradually become moderate during the storm. Freezing level about 1000 metres.Friday: There should be a bit of a lull in the storm before the next pulse comes on-shore Friday evening. Expect flurries and light to moderate Westerly winds during the day, increasing to heavy snowfall and strong Southwest winds in the evening. Freezing level dropping below 700 metres.Saturday: 20-30 cms of new snow by Saturday morning with strong Southwest winds and rising freezing levels.
Avalanche Summary
The warm new storm snow is not expected to bond well to the shallow weak snowpack. Expect natural avalanche activity and easy triggering from skiers and sledders.
Snowpack Summary
New storm slab is 30 cm deep and growing. Strong Southwest winds are transporting snow and developing deep pockets that are sitting above recent weak surface layers. Rising temperatures during the storm are expected to develop a relatively warm storm slab above a cold layer of wind crusts, surface hoar and surface facets. Snow profile information from the Shames area on Monday before the storm on a South-Southwest aspect at 950 metres, showed a 70 cm base with loose snow in the top 20 cms above a stiff 4 cm crust that is sitting above a softer facet layer. There was another hard crust about 30 cms above the ground. The new storm is a great deal of change for this young and weak snowpack to handle.
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.