Regions
Northwest Coastal.
Touchy wind slabs are the main concern at treeline and above. The avalanche danger may be higher in the north of the region where very large, full depth avalanches remain a concern.
Confidence
Moderate - The weather pattern is stable
Weather Forecast
Steady weather pattern for the Northwest: Cool and mostly clear, moderate outflow winds.MONDAY: Mix of sun and cloud / Moderate to strong east wind / Alpine temperature -14TUESDAY: Sunny / Moderate east wind / Alpine temperature -14WEDNESDAY: Sunny / Moderate east wind / Alpine temperature -15
Avalanche Summary
Size 2 wind slabs were remotely triggered the south Douglas zone on Saturday, releasing from shallow cross-loaded gullies. Several natural avalanches to Size 2.5 were observed in lee alpine features on Friday near Shames ski hill. (Hard) wind slabs were reactive even on small, relatively low angled slopes at treeline in the same area. In the northern most parts of the region near Bell2 or Ningunsaw there are still reports of natural and skier triggered avalanches to Size 2.5 stepping down to basal facets in the alpine and tree line.
Snowpack Summary
The snow from last week has been redistributed by continuous strong to extreme (north) easterly outflow winds, creating widespread wind effect. Touchy wind slabs on south/southwest aspects up to 45cm thick were running on relatively low angled terrain near 1300m in the Shames backcountry. At lower elevations, precipitation fell as rain and a surface (or near-surface) crust may now be found below about 1000m. Below the recent storm snow the January 18th rain crust is producing moderate sudden shears down 85cm in snowpack tests; however, it isn't showing signs of propagation being likely. The snowpack below this is generally strong and well settled. The exceptions are areas around Bear Pass and Ningunsaw where basal facets (under wind slab) remain an ongoing concern, especially in shallow snowpack areas.
Problems
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.
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.