Regions
Northwest Coastal.
Conditions may change dramatically with aspect and elevation across the region. Avalanche danger may be lower in areas that receive less than 20cm of snow overnight and through Sunday.
Confidence
Moderate - Intensity of incoming weather systems is uncertain on Sunday
Weather Forecast
SUNDAY: snow overnight with flurries continuing through the day, up to 20cm expected for coastal areas and around 15cm for inland regions, moderate southerly winds, 1000m freezing level. MONDAY: flurries continue with accumulations of up to 10cm possible, light to moderate southwesterly winds, 800m freezing level. TUESDAY: Light snow with another 10cm possible before clearing, light easterly winds, 1000m freezing level.
Avalanche Summary
Widespread avalanche activity was reported on Thursday with numerous natural and artificially controlled avalanches up to size two at all elevations. Wind slabs, storm slabs and cornice releases were reported at alpine and treeline elevations while several glide cracks and large loose wet avalanches released bellow treeline. On Wednesday a couple of very large wind slab avalanches are suspected to have run on the early February crust in the bear pass highway corridor.
Snowpack Summary
Recent snow has been heaviest in the north of the region, creating storm and wind slabs. Up to 30cm of new snow now sits above old wind effected snow, a crust on sunny aspects or surface hoar in isolated sheltered and shady locations. Previous strong winds created widespread wind slabs and wind pressed surfaces at alpine and treeline elevations. An old crust buried around February 12th that extends up to about 2000m can now be found down 60-80cm. A layer of surface hoar buried late in January remains a lingering concern in the far North of the region.
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.
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.