Northwest Coastal

Dangerous avalanche conditions are expected to persist into Sunday as the snowpack continues to adjust to the recent heavy precipitation, strong winds and warm temperatures.

Moderate - Freezing levels are uncertain on Sunday

An amplifying ridge of high pressure will deflect weather systems to the northwest and cause them to weaken as their low centres brush Haida Gwaii. Light to moderate precipitation will stretch from Bella Coola northwards through the Northwest Coastal ranges with freezing levels peaking between 1500 and 1700 m Saturday afternoon through Sunday for areas such as Shames. SATURDAY NIGHT: Freezing level around 1500 m, strong south/southwest wind, 3 to 10 mm of precipitation falling as snow in higher elevation terrain.SUNDAY: Overcast, freezing level around 1500 m, moderate to strong south/southwest wind, 2 to 8 mm of precipitation falling as snow above 1500 m.MONDAY: Overcast, freezing level around 1500 m in the morning rising to about 2000 m in the afternoon, light to moderate south/southwest wind, trace of snow possible.TUESDAY: Scattered cloud cover, freezing level around 2000 m, light to moderate southerly wind, no significant precipitation expected.

On Friday steep alpine features in Bear Pass produced natural avalanches from size 2.5 to 3.5, natural avalanches from size 1.5 to 2.5 were reported at and below treeline.  In the Skeena corridor loose wet avalanches to size 1.5 were reported at and below treeline.  Visibility was limited, but natural avalanches to size 3 were reported from several avalanche paths.  Natural avalanche activity likely continued through Saturday.An avalanche incident was reported in the Shames backcountry area on Thursday. The incident involved two skier triggered avalanches occurring in succession with two people involved and partially buried. The details can be found on the Mountain Information Network. (here)Several natural and explosives triggered avalanches to size 2 were reported in the region on Thursday.

The Northwest Coast has seen upwards of 100 mm of precipitation since Wednesday. Depending on elevation and location in the region, this came in as snow, rain and freezing rain. Strong to extreme winds, warm temperatures and ongoing snowfall/rainfall will be promoting widespread slab formation. The snowpack is likely rain-soaked at lower elevations, particularly in southern portions of the region around Terrace.In some sheltered areas, the new snow is sitting on a weak layer of surface hoar (feathery crystals). 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 decreasing, but it could be triggered by humans in shallow snowpack areas. The potential may also exist for storm slab avalanches to step down to this layer, resulting in large avalanches.In the northern part of the region, near Ningunsaw pass, a couple of weak layers of surface hoar may be found down approximately 150 to 220 cm.