Regions
Northwest Coastal.
Cracking and whumpfing is showing that our new snow hasn't stabilized yet. The greatest concern is in areas that have been variably pressed and loaded by recent winds.
Weather Forecast
Wednesday night: Mainly cloudy. Moderate southwest winds increasing to strong in the morning.Thursday: Cloudy with flurries beginning midday and bringing 3-5 cm of new snow by end of day, easing overnight. Strong southwest winds. Alpine high temperatures around -1.Friday: Cloudy with scattered rain showers bringing up to 5 mm of rain, continuing and switching to snow overnight. Possible minimal new snow accumulation in high alpine locations. Moderate to strong south or southwest winds increasing over the day. Alpine high temperatures around +1 or +2 with freezing levels reaching 2200 metres before decreasing overnight.Saturday: Cloudy with heavy snowfall bringing 20-30 cm of new snow, ending in the evening. Strong southwest winds decreasing over the day. Alpine temperatures around -2 with freezing levels dropping from about 1500 to 1000 metres over the day.
Avalanche Summary
No new avalanches have been reported in the region. Reports over the weekend documented reactive slabs and evidence of recent avalanches. In the north of the region, storm slab, wind slab, and loose dry avalanches to size 2 were reported on Saturday and Sunday.
Snowpack Summary
Around 50 cm recent snow is being affected by wind, forming slabs and loading snow in lee and cross-loaded terrain. This snow covers a variable surface of wind-affected and faceted snow, a weak layer of surface hoar in more protected areas, but more predominantly a rain crust/surface hoar combination below 1500 m. Recent reports from the Shames area suggest a strengthening bond between the recent snow and the underlying crust now down about 50 cm.Below the interface described above, old wind-affected storm snow is expected to have formed a good bond with the underlying snowpack, although exceptions exist in the far north of the region. Here, the old storm snow may overlie a weak layer of surface hoar (feathery crystals). This layer was identified as the failure plane in several large avalanches in the north of the region last week. It has not shown in reports elsewhere.For most of the region, a weak layer of facets (sugary snow) buried in early December exists down 180-250 cm. The likelihood of triggering this layer is generally low, but it could be triggered by humans in shallow snowpack areas, particularly in the north of the region.
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.