Regions
South Coast Inland.
Observations of reactive surface hoar have renewed concern for slab avalanche danger in the north of the region. Avalanche danger is generally LOW in the south of the region, requiring normal cautions.
Weather Forecast
Saturday: A mix of sun and cloud. Light northeast winds. Freezing level to 1400 metres with alpine high temperatures of -4, slightly warmer in the south of the region. Sunday: Cloudy with isolated flurries and a trace of new snow. Light southwest winds. Freezing level to 1300 metres with alpine temperatures around -5, slightly warmer in the south of the region.Monday: A mix of sun and cloud. Light southwest winds. Freezing level to 1400 metres with alpine temperatures around -4, slightly warmer in the south of the region.
Avalanche Summary
Reports from Thursday included one observation small storm slab releasing with a ski cut on the steep flank of a couloir in the north of the region. Several other recent natural storm slab releases were observed in the same area, ranging from size 1-2 with crown fracture depths of 10-30 cm. North aspects were the most active.Monday's reports showed one size 1.5 wind slab that released with skier traffic on a steeper north aspect (near ridgecrest) in the alpine near Birkenhead Lake. Several solar triggered loose wet releases were reported, averaging size 1.5-2 but reaching size 3 in isolated areas.
Snowpack Summary
5-10 cm of new snow accumulated on Wednesday. In most areas, the new snow has buried a breakable crust formed after days of warm temperatures and sunshine. On higher elevation north aspects in the north of the region, is overlies a mix of about 20 cm of either low density or wind-redistributed storm snow from last week. This older storm snow sits on a sun crust on steep south-facing slopes, cold dry snow and possibly small surface hoar on shady aspects. Recent reports have shown prolonged slab reactivity in areas in the north of the region where this surface hoar exists.In the north of the region a weak layer buried in mid-February is about 40-50 cm below the surface and has been reactive in some snowpack tests. The layer is composed of sugary facets, a sun crust on solar aspects, and surface hoar that is present at and below treeline. The snowpack is well settled in the south of the region around the Coquihalla and in Manning Park.Variable winds in the past month have created cornices on many alpine ridgelines. They become touchier as daily temperatures rise and with the strong late winter sun on clear days.
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.