Forecast snow amounts are uncertain. If snow amounts at treeline exceed 20cm, the danger will likely be high there too.
Confidence
Poor - Forecast snowfall amounts are uncertain
Weather Forecast
Synopsis: A broad upper level trough settles in over the Southern Coast which should generate significant precipitation through the weekend.Saturday: Freezing Level: 600m rising to 1300 - 1500m Precipitation: 5-15mm | 5 - 20cm; Treeline Wind: Light, South | Ridgetop Wind: Strong, SouthSunday: Freezing Level: 500m rising to 1200 - 1500m Precipitation: 2-5mm | 2-10cm; Treeline Wind: Moderate, SW | Ridgetop Wind: Strong, SWMonday: Freezing Level: 400m rising to 1400 - 1800m; Precipitation: Trace; Treeline Wind: Light, SE | Ridgetop Wind: Light, SE
Avalanche Summary
Avalanche activity on Thursday was limited to point releases out of steep solar terrain. These loose snow avalanches ran to size 1.5, involving the upper 20 cm of the snowpack.
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.