Regions
Northwest Coastal.
Stormy weather is maintaining heightened avalanche danger in the region. This forecast is based on limited observations and demands a cautious approach combined with independent information gathering.
Weather Forecast
Saturday: Cloudy with scattered flurries and 5 to 10 cm of new snow, increasing overnight. Light to moderate south winds. Freezing level to 600 metres with alpine temperatures of -5Sunday: Continuing flurries bringing approximately 5 cm of new snow. Strong south winds. Freezing level rising to 1000 metres with alpine temperatures of -2.Monday: Another round of flurries bringing 5-10 cm of new snow. Strong southwest winds. Freezing level to 1000 metres with alpine temperatures around -3.
Avalanche Summary
Reports from Wednesday included observations of several natural wind slab releases from steep, north-facing alpine terrain in Bear Pass. These were triggered by rain. Reports from Sunday showed evidence of a natural loose wet avalanche cycle focused on steep, low elevation rock slabs along Highway 16 between Terrace and Prince Rupert. Observations of high elevation terrain have been very limited. Please post your observations to the Mountain Information Network (MIN)
Snowpack Summary
Approximately 60 mm of precipitation fell over the region over the midweek storm, accompanied by moderate to strong winds and freezing levels of around 1100 metres. Under these conditions, rain saturated and eroded the snowpack at lower elevations while new snow accumulations of up to 60 cm blanketed the alpine. New snow depths are heavily elevation-dependant, with new snow depths below treeline ranging from 0 to 20 cm. Below the new snow, two weak layers are noted to have formed during the early season. (October 31 and November 11) Although their widespread presence is fairly certain, very few observations or tests of their reactivity exist. With that said, ongoing loading of the upper snowpack carries the potential to activate these deeper weak layers. Looking further to the north of the region near Ningunsaw, the snowpack is starkly different. Here, much drier, colder early season conditions produced a shallow snowpack composed mainly of weak, sugary snow. Snow depths in this part of the region are largely below threshold depths for avalanching.
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.
Loose Wet
Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.