Regions
Northwest Inland.
The snow load on a layer of buried surface hoar may be reaching the threshold for surprisingly large avalanches, especially at tree-line.
Confidence
Low - Due to the number of field observations
Weather Forecast
A series of powerful storms are going to wallop the coast over the coming days bringing heavy precipitation and strong winds that should spill over into the inland regions. Tuesday should see snowfall accumulations of between 5 and 15 cm. With another 10cm expected by Friday. Winds will be moderate to strong from the southwest and freezing levels should stay below 1000m.
Avalanche Summary
It sounds like there were touchy conditions out there over the weekend. Reports of some large skier triggered and skier controlled avalanches from tree-line suggest that the load on the recently buried surface hoar is reaching critical levels.
Snowpack Summary
New snow is falling on a variety of old surfaces including a crust at lower elevations and south facing slopes, or facets and surface hoar on cooler shaded features. The distribution of surface hoar is definitely our biggest knowledge gap. Bellow this we're still dealing with a thin early season snowpack.
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.