Avalanche Forecast

Issued: Mar 19th, 2018 5:20PM

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

Avalanche Canada ghelgeson, Avalanche Canada

Skiers continue to trigger large avalanches on buried surface hoar which means it is not full "go time" yet, especially on the bigger lines. This layer has not been reactive in the south of the region where the danger is generally LOW.

Summary

Confidence

High - Timing, track, or intensity of incoming weather system is uncertain on Thursday

Weather Forecast

Tuesday offers a bit of a drying trend for most of the province. A low approaching from the Gulf of Alaska may bring some precipitation to the region beginning Wednesday afternoon.TUESDAY: Broken cloud cover, freezing level beginning at 500 m rising to 1500 m, moderate westerly wind, trace of precipitation possible. WEDNESDAY: Broken cloud cover, freezing level beginning at 600 m rising to 1600 m, light to moderate southerly wind, trace of precipitation possible.THURSDAY: Broken cloud cover with some clearing in the afternoon, freezing level beginning around 700 m rising to 1400 m, moderate to strong southerly wind, 2 to 8 mm of precipitation possible.

Avalanche Summary

On Sunday another skier triggered avalanche was reported from a north/northeast facing feature between 1900 and 2000 m. The size 2 avalanche failed on the March 8th surface hoar with a crown depth of 20 cm. Small loose wet avalanches were also triggered by direct solar input in steep rocky terrain.On Saturday two size 1.5 skier triggered avalanches were reported from steep northeast facing terrain at 2200 m. The slabs were up to 20 cm in depth likely failing on the recently active surface hoar.We received a great MIN report on Saturday that details a size 3 skier triggered avalanche on the northwest face of Matier that likely occurred in the last few days. More details here.On Friday two size 2 slab avalanches were reported from a north/northeast facing feature between 2100 and 2400 m on the Duffey. The slabs were 20 to 40 cm in depth and failed on surface hoar up to 4 mm in size.

Snowpack Summary

5 to 10 cm of new snow fell March 14th. In most areas the new snow buried a breakable crust formed by days of warm temperatures and sunshine. In the north of the region, polar aspects (those that face north and east) are harboring cold snow and a tricky buried weak layer down 20 to 40 cm below the surface. The layer is widespread in the alpine and at treeline, but it is not everywhere. The layer is composed of surface hoar on polar aspects and a sun crust on solar aspects. This layer continues to produce human triggered avalanches on polar aspects on the Duffey and has not been reported in the south of the region.In the north of the region a weak layer buried mid-February is about 40 to 50 cm below the surface and has been reactive in 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
Large storm slabs continue to be triggered by skiers in high elevation north and east facing terrain where old storm snow rests on reactive surface hoar. Loose wet avalanche activity is unlikely Tuesday due to increased cloud cover.
Heads up! Cornices loom large and if they fail, they will likely initiate storm slabs.Be very careful with open slopes and convex rolls, especially in more extreme terrain.Carefully evaluate big/extreme terrain features before committing to them, its not full go time yet.

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1.5 - 2

Valid until: Mar 20th, 2018 2:00PM