Archived

Avalanche Forecast

Apr 4th, 2018–Apr 5th, 2018

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

2: Moderate

The avalanche danger rating below treeline will be moderate

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

2: Moderate

The avalanche danger rating below treeline will be moderate

Regions: Northwest Coastal.

It's been a few days since a large avalanche cycle affected this region, but it may still be possible to trigger a large avalanche, especially from convex, wind-loaded terrain features.

Confidence

Moderate - Due to the number of field observations

Weather Forecast

Thursday: 5-10 cm new snow with more in the south than the north. Freezing level around 500 m. Strong southeasterly winds.Friday: Up to 5 cm new snow. Freezing level around 500 m. Moderate southeasterly winds diminishing in the afternoon.Saturday: Mostly dry. Freezing level around 900 m. Light easterly winds.

Avalanche Summary

On Tuesday, there was a size 2 natural wind slab avalanche reported from a north aspect alpine slope. There were also several small (size 1), thin soft slab avalanches on recently wind-loaded features. A large (size 3) glide avalanche was reported from a N-NW slope below treeline. Additionally, steep south aspect slopes released loose wet avalanches in the afternoon.Last week, large persistent slab avalanches were reported on east to northeast aspects at all elevations, failing on the early-March and mid-March layers. There have been no reports of avalanches on these layers so far this week.

Snowpack Summary

10-30 cm of new snow sits above a variety of crusts on all but high north aspects.In the south of the region, 70 to 90 cm of snow overlies two layers of surface hoar. The layers are most prominent on north to east aspects and were buried early-March and mid-March. In the north of the region, these layers are around 40 cm deep.Shallower parts of the region, such as the far north, have weak sugary facets near the bottom of the snowpack.

Avalanche Problems

Wind Slabs

Wind slabs are expected to form where recent new snow has blown in to thicker and denser slabs.

Be careful with wind loaded pockets, especially near ridge crests and roll-overs.If triggered the storm/wind slabs may step down to deeper layers resulting in large avalanches.

Aspects: North, North East, East, South East, South.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 2

Persistent Slabs

A buried surface hoar layer produced large slab avalanches at the end of March. There's some uncertainty as to how long this layer will remain a problem, but it's best to carefully evaluate sheltered north and east slopes.

Pay attention to overhead hazards like cornices which could trigger persistent slabs.Use extra caution in open trees and sheltered features where surface hoar may be preserved.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Unlikely - Possible

Expected Size: 2 - 3