Regions
Northwest Coastal.
Weather Forecast
A strong upper ridge of high pressure will dominate the weather pattern for a week or more. However, a weakening Pacific front will move through the ridge Saturday and give light to moderate precipitation through Saturday evening.Saturday Night: Freezing Level: 1100m; Precip: 2/12mm 4/15cm Wind: Strong, SWSunday: Freezing Level: 800m; Precip: Nil; Wind: Light, West.Monday: Freezing Level: Rising throughout the day to 2000m. Precip: Trace; Wind: Mod, South.Tuesday: Freezing Level: 2500m; Precip: Nil; Wind: Mod, SW.
Avalanche Summary
Isolated naturals to size 1.5 were reported from steep solar aspects Friday afternoon. Explosives are still producing results in the alpine if the technician finds just the right spot. On January 13/14 there was a widespread avalanche cycle involving all aspects/elevations. Multiple natural releases up to size 4.0. Most of these avalanches would have run on the early January surface hoar layer buried under the storm snow at treeline and below treeline in all the region and some on the deep persistent basal facet layer in the alpine in the Northern part of the region.
Snowpack Summary
In the North, the early January surface hoar buried at around 1 m deep at treeline and below treeline is showing to be a main concern since it proved to be very active during the last storm even on low angled terrain. The basal facets also became reactive in the last rapid loading. These are found in the alpine and at treeline under over 2 m of snow in some areas. The persistent weak layers mentioned above are also found in the Southern part of the region, but are not showing as much reactivity. The extensive wind slab formation that happened during the SW wind event have most likely started to bond to the underlying surface in the alpine and at treeline. However, expect steep crossloaded or steep lee features to weaken during the day especially if the sun hits those slopes.
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.