Regions
Northwest Coastal.
Cool and stable weather should mean a gradually strengthening snowpack.
Confidence
Moderate - Due to the number of field observations
Weather Forecast
The storm track will follow the Canada -- USA border over the next few days so the Northwest should be cool and dry.Tuesday: Mix of sun and cloud, dry, light to moderate northeast winds, and alpine temperatures around -5 C.Wednesday: A temperature inversion could mean sunshine in the alpine but grey and cold below the valley cloud. Nil precipitation. Alpine temperatures could near freezing; colder at low elevations. Light but gusting northwest wind. Thursday: Mix of sun & clouds. Dry. Light but gusting north wind. Alpine temperatures around -5 to -10 C.
Avalanche Summary
The north part of the region reported up to size three natural avalanches over the weekend. Poor visibility limited observations in the south but no new avalanches were reported.
Snowpack Summary
The region picked up 20 to 60cm of storm snow over the weekend accompanied by winds out of the southwest, west, northwest, and even a bit of southeast. This has likely led to the development of a cohesive slab, especially in wind exposed features. These new storm and wind slabs rest on a rain saturated snowpack between valley bottom and 800m. Above 800m, the new storm snow rests on settled old snow, or a melt freeze crust that is 3 to 15cm thick. Below this crust the mid-pack is strong, but there are reports of a feathery surface hoar layer on or right around this crust in sheltered locations. There is a second prominent crust that is associated with facets buried at the end of October, look for this widespread interface down around 100 to 200cm below the surface.
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.