Avalanche Forecast

Issued: Mar 16th, 2018 4:47PM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is low. Known problems include Storm Slabs.

Avalanche Canada cgarritty, Avalanche Canada

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.

Summary

Confidence

High -

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

An icon showing Storm Slabs
Recent reports are showing continued slab reactivity on shaded aspects where recent snowfall overlies surface hoar. South aspects become an additional daily concern as sun and warming set up loose wet avalanche conditions.
Extra caution needed around cornices with current conditions.Use extra caution on solar slopes or if the snow is moist or wet.Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Mar 17th, 2018 2:00PM

Login