Archived

Avalanche Forecast

Apr 3rd, 2018–Apr 4th, 2018

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

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

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

Regions: Northwest Coastal.

Fresh storm slabs will be reactive to human triggers at higher elevations. Use extra caution on south-facing slopes when the sun is out.

Confidence

Moderate - Due to the number and quality of field observations

Weather Forecast

WEDNESDAY: Mostly sunny, light wind, freezing level up to 600 m, alpine high temperatures near -8 C.THURSDAY: Snow starting in the morning with 4-8 cm accumulations by the afternoon, strong south wind, freezing level near valley bottom, alpine high temperatures near -10 C.FRIDAY: Continued light flurries with another 5 cm of snow, moderate south wind, freezing level up to 600 m, alpine high temperatures near -8 C.

Avalanche Summary

Preliminary reports from Tuesday suggest some avalanche activity likely occurred at higher elevations during the storm.No new avalanches were reported on Monday and activity on Sunday was limited to a few small loose avalanches on steep sun-exposed slopes.Last week, large persistent slab avalanches were reported on east to northeast aspects at all elevations. These were failing on the early-March and mid-March layers.

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

Storm Slabs

15-30 cm of new snow with moderate west wind has formed fresh slabs. Human triggering is likely in steep terrain and where the wind has formed thicker deposits.

If triggered, storm slabs may step down to deeper layers, resulting in large avalanches.Use caution on open slopes and convex rolls Minimize exposure to steep sun exposed slopes when the solar radiation is strong.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

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.

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

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

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 2 - 2.5