Regions
Northwest Inland.
Strong winds and new snow have resulted in Considerable avalanche danger. If you see more snow than forecast in your area, consider these danger ratings to be a bit low.
Confidence
Poor - Timing, track, or intensity of incoming weather system is uncertain
Weather Forecast
Moderate Southerly winds overnight with a 2-3 cms of new snow and freezing levels at valley bottoms. Overcast with a 2-3 cms of new snow during the day on Sunday. Cooler and drier on Monday with moderate Westerly winds. The next pulse of moisture is expected on Tuesday.
Avalanche Summary
There are no new avalanche reports from the region. The forecast new storm is expected to develop a new storm slab that may increase avalanche activity.
Snowpack Summary
The new storm is expected to develop a storm slab above the dusting of new snow which overlies weak surface hoar reported to exist up to at least treeline elevation. Below the new snow you'll likely find wind-scoured surfaces and old wind slabs in exposed terrain, and settled storm snow closer to treeline. Near the base of the snowpack, weaknesses such as the mid-November crust-facet layer are still of concern. I'd use extra caution around steep, unsupported high elevation terrain as avalanches at this interface could propagate over wide distances.
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.
Deep Persistent Slabs
Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.