Fresh storm slabs may bond poorly to the latest melt-freeze crust. Watch for how the new snow is bonding to the old surface.
Confidence
Moderate - Intensity of incoming weather systems is uncertain
Weather Forecast
Active weather returns on Tuesday with moderate amounts of snow and cool temperatures. TUESDAY: Snow. 5-10cm overnight with 10-15cm accumulation throughout the day. Ridge wind moderate from the east. Temperature near -2. Freezing level 500 m.WEDNESDAY: Sunny with cloudy periods. Ridge wind moderate northerly. Freezing level 600 m.THURSDAY: Cloudy with isolated flurries. Ridge wind moderate from the north west. Temperature near -3. Freezing level 400 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. Since then, rain and subsequent cooling temperatures have 'locked up' the upper snowpack and avalanche activity has ceased.
Snowpack Summary
Temperatures got quite warm at the tail end of Sunday's storm, with up to 30mm rain falling on 15-20cm snow. Clearing overnight into Monday morning resulted in a widespread melt-freeze surface crust. The rained-on snow from the weekend is bonding well to the previous melt-freeze crust from early December's warm weather.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.