Regions
Northwest Coastal.
Conditions below tree-line vary greatly with elevation. Many areas are still below the threshold for avalanches but buried surface hoar may be present as you approach tree-line.
Confidence
Low - Due to the number of field observations
Weather Forecast
SATURDAY: Flurries with up to 10cm localized to costal regions, light southwest winds, freezing level at 500m SUNDAY: mainly clear, moderate south east winds, freezing level at valley floor 1000m. MONDAY: mainly clear with flurries possible in the afternoon, light northwest winds, freezing level at valley floor.
Avalanche Summary
Widespread avalanche activity was reported through recent storm, with several avalanche releasing on the layer of surface hoar now buried between 70cm and 1m deep. Natural activity on this layer has slowed since the storm ended on Thursday. Explosive avalanche control around Shames produced smaller storm slab avalanches that released on mid-storm instabilities under larger triggers.
Snowpack Summary
Up to a meter of settled snow fell in the last week which may be sitting upon a layer of buried surface hoar. This layer has the potential for remote triggering and wide propagations. It is likely to be lurking on sheltered north facing slopes at or just below tree-line although it has been spotted well into the alpine in Bear Pass. Strong north through easterly winds overnight on Thursday have reverse loaded lee features. Low, below tree-line elevations may still be bellow threshold for avalanches in many places.
Problems
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.
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind 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.