The forecast new snow and wind should increase the avalanche danger. If the storm comes early the danger may be high by Friday afternoon.
Confidence
Fair - Timing, track, or intensity of incoming weather system is uncertain on Friday
Weather Forecast
Overnight and Friday: Freezing level dropping down to about 600 metres overnight. Snow starting in the early morning near the coast and moving inland as a warm front moves across the region. Expect 15-20 cm of snow near the coast, and 10-15 cm inland during the day. Southwest winds should build to strong values by the afternoon and freezing levels should rise to about 1500 metres.Saturday: A trailing cold front should bring another 15-20 cm of snow to near coastal areas and 5-10 cm further inland by morning. Winds should slow to moderate Southwest during the day as snow continues. Freezing level rising to about 1500 metres during the day.Sunday: Snow ending overnight or early morning. Light Southerly winds and freezing levels rising to about 1300 metres.
Avalanche Summary
No new reports of avalanches.
Snowpack Summary
There may be some areas where the recent snow does not bond well to melt-freeze crusts on solar aspects. The forecast new storm should add a new load above these weak bonds and may be sensitive to triggering from light additional loads like skiers or riders. The persistent weak layers from early March and early February continue to be a concern. The March weak layer of wind-scoured crusts, melt-freeze crusts, and/or surface hoar is reported to be down 70-80 cm. The February crust/facet/surface hoar layer is now deeply buried down 150-250 cm and may still be triggered by heavy loads like cornice falls or storm slab avalanches in motion. Long fracture propagations resulting in very large avalanches are possible with this layer. Avalanches releasing on these layers may step down to the ground during periods of strong solar radiation or warm spring rain.
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.
Deep Persistent Slabs
Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.