Regions
Northwest Coastal.
Avalanche danger is expected to remain HIGH tomorrow in the Alpine and then increase to HIGH at all elevations due to the next pulse of warm Pacific moisture on Saturday.
Confidence
Fair - Intensity of incoming weather systems is uncertain
Weather Forecast
Overnight and Friday: Snow this evening is expected to end during the night. Winds will remain strong Westerly during the day and the freezing level should drop back down below 1000 metres.Saturday: The next strong pulse of Pacific moisture should start overnight Friday or early Saturday morning. Heavy snowfall 30-50 cm with extreme Southwest winds and rising freezing level to about 1600 metres.Sunday: Precipitation should taper off to flurries by morning. Winds will remain strong Southwesterly and freezing levels should drop down to about 700 metres.
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
The new storm slab continues to grow. 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.