Regions
Northwest Inland.
Confidence
Fair - Timing, track, or intensity of incoming weather system is uncertain
Weather Forecast
Thursday should be relatively dry before the next frontal system reaches the coast on Thursday evening. Light precipitation is expected for the inland region on Friday and Saturday. Greater amounts are expected for the south of the region.Thursday: Cloudy, dry conditions during the day, snowfall in the evening, freezing level am: 500m pm: 900m, ridgetop wind light S-SWThurs. Night/Friday: Snowfall 5-15cm, freezing level am: 600m pm: 1200m, ridgetop wind 30-50 km/h S-SWSaturday: Snowfall light to moderate, freezing level am: 500m pm: 1000m, ridgetop wind light to moderate S-SW
Avalanche Summary
A natural cycle to size 1 is being reported in the south of the region on Wednesday. In the north, a natural cycle is also reported for Tuesday/Wednesday and the typical avalanche size is expected to be larger than in the south.
Snowpack Summary
Roughly 40-60 cm of dense storm snow now sits on a weak layer consisting of surface hoar and/or a thick layer of faceted snow on shady slopes at all elevations, a sun crust on steep solar aspects, and various wind affected surfaces in exposed terrain. Strong southwest winds have created dense wind slabs on exposed lee slopes and in cross-loaded features. Moist/wet snow or melt-freeze crusts in the upper snowpack are likely at lower elevations, below roughly 1200m. The early February weak layer of facets, crusts, and/or surface hoar is buried down about 60-100 cm. Test results and isolated avalanche activity suggest this layer is still reactive to human-triggering. Basal facets and depth hoar remain a concern in areas with thin or variable snow cover.
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.