Regions
Northwest Coastal.
Although the storm has eased off, storm slabs are still likely to be encountered and could be reactive to human triggering, especially in wind loaded areas and with continued warm temperatures.
Weather Forecast
SUNDAY NIGHT - Cloudy with clear periods / light northeast winds / alpine low temperature near -2 / freezing level 1000 m MONDAY - A mix of sun and cloud / light northwest winds / alpine high temperature near 0 / freezing level 1000 mTUESDAY - Cloudy with scattered flurries / southwest winds, 10-20 km/h / alpine high temperature near +1 / freezing level 1000 m WEDNESDAY - Flurries, 5-10 cm / southwest winds, 20-40 km/h / alpine high temperature near 0 / freezing level 1000 m
Avalanche Summary
Several natural and explosives triggered avalanches to size 3 were reported in the region on Sunday.A few explosives triggered avalanches to size 2.5, and a few natural avalanches to size 1.5 were reported in northern portions of the region on Saturday.On Friday, a few natural and explosives triggered avalanches to size 3 were reported in the region, mainly in the northern areas of the region. Some of these avalanches reportedly failed on the recently buried surface hoar layer.A size 2.5 wind slab avalanche was triggered remotely (from 20 m away) just south of the Seven Sisters Provincial Park area on a southeast aspect at 1700 m on Wednesday.
Snowpack Summary
20-30 cm of recent snow has fallen, mainly in alpine areas and further north towards Bear Pass. This precipitation mainly fell as rain at lower elevations, and to higher elevations in the south of the region. The new snow sits on a weak layer of surface hoar (feathery crystals) that may coexist with a sun crust on sun-exposed slopes. Below approximately 1600 m (1000 m near Bear Pass), the recent snow is likely rain-saturated, and sits on a melt-freeze crust and surface hoar combination. In the Shames area, reports suggest that the new snow is bonding to the crust. Avalanches were observed failing on this layer below treeline in the Bear Pass area on Friday.There may be another layer of surface hoar in shady and wind sheltered areas that is now buried approximately 50 cm.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.