Fresh storm slabs may bond poorly to chunky, variable crusts. Watch for how the new snow is bonding to the old surface.
Confidence
Moderate - Due to the number of field observations
Weather Forecast
Monday will see a brief lull in the active weather pattern before significant precipitation arrives on Tuesday.MONDAY: Cloudy with isolated flurries. Accumulation of 5 cm possible. Ridge wind light from the west. Temperature near 0. Freezing level 800 m.TUESDAY: Snow. Accumulation 20-30 cm. Ridge wind light from the southeast. Temperature near -1. Freezing level 700 m. WEDNESDAY: Sunny with cloudy periods. Ridge wind moderate northerly. Freezing level 600 m.
Avalanche Summary
On Sunday, skiers were able to trigger Size 1 storm slabs on westerly aspects near tree line in the North Shore mountains.
Snowpack Summary
10-25cm of snow from the weekend now sits on a widespread melt-freeze crust, which exists on all aspects and elevations. How well the incoming new snow bonds to this crust will be a critical determinant of avalanche danger on Monday.Below the snow surface, the upper snowpack is well-settled and bonding well to the late-November rain crust. Below tree line the snow pack is thin and there are many early season hazards. Snowpack depths range from 40 cm at 800 m elevation to 200 cm at 1220 m.
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.