Archived

Avalanche Forecast

Apr 6th, 2017–Apr 7th, 2017

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

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

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

1: Low

The avalanche danger rating below treeline will be low

Regions: Northwest Coastal.

Exposed terrain has been walloped by strong winds. Watch for cornices and wind slabs at higher elevations.

Confidence

High -

Weather Forecast

FRIDAY: Cloudy with sunny periods and isolated flurries, moderate southeast wind, freezing level up to 1300 m after an overnight freeze.SATURDAY: 5-10 cm of new snow, light southeast wind, freezing level around 1300 m.SUNDAY: Cloudy with light flurries, moderate south wind, freezing level around 1200 m.

Avalanche Summary

Several natural and explosive triggered wind slabs were reported on Wednesday in north and west alpine features (up to size 2.5). Several avalanches were triggered by cornice falls earlier in the week, including one size 2.5 persistent slab avalanche on the February weak layer. A snowmobiler had a close call with a cornice fall on the weekend at South Douglas (click here for MIN report).

Snowpack Summary

Touchy wind slabs may still exist at higher elevations, as Wednesday's storm delivered 15-20 cm of snow above 1000 m with strong to extreme winds. Extensive wind affect is expected in exposed terrain. An overnight freeze will likely form a crust at lower elevations that will deteriorate with the heat of the day. A weak layer of facets and crusts is buried 100-150 cm deep. The layer has been unreactive recently, but a heavy trigger such as a cornice fall or intense warming may still be able to trigger it.

Avalanche Problems

Wind Slabs

Very strong winds on Tuesday night and Wednesday likely formed reactive wind slabs in the lee of exposed terrain.

Use caution on open slopes and convex rolls Use caution in lee areas. Recent wind loading has created wind slabs.Be aware of the potential for wide propagations due to the presence of hard windslabs.

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

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 2

Cornices

Large cornices may become weak with daytime warming and have potential to trigger slabs on the slopes below.

Give cornices a wide berth when traveling on ridges.Avoid steep slopes below cornices.Even small cornice falls may trigger larger avalanches.

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

Elevations: Alpine.

Likelihood: Possible

Expected Size: 2 - 3