Archived

Avalanche Forecast

Apr 10th, 2017–Apr 11th, 2017

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

1: Low

The avalanche danger rating at treeline will be low

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

1: Low

The avalanche danger rating at treeline will be low

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: Kootenay Boundary.

There are lingering wind slabs on northeast aspects, and watch for the influence of the sun on southern aspects.

Confidence

Moderate - Due to the number of field observations

Weather Forecast

Tuesday: Flurries. Mostly calm winds. Freezing level around 1600 m. Wednesday: Dry with sunshine in the morning, becoming cloudy with some flurries in the afternoon. Winds 20-30 km/h from the southeast. Freezing level around 1600 m. Thursday: 15-20 cm new snow overnight Wednesday and into Thursday. Winds light southeasterly. Freezing level around 1500 m.

Avalanche Summary

On Monday, a size 2 avalanche was ski cut in recent storm snow in the Monashees. A similar sized avalanche was also naturally triggered. On Saturday there was an accidentally triggered size 2 wind slab reported in the Valhallas. I think this kind of shallow wind slab in alpine terrain is representative of a lingering wind slab concern: localized pockets, lee and cross-loaded features, around 20 to 30 cm thick. Although not in this region, Saturday's fatal avalanche accident on Mt. Harvey (South Coast Mountains) highlights several of the risks posed by cornices: multi-ton snow boulders serve as large triggers potentially releasing big avalanches on the slopes below, and they can break well back making for tricky travel along ridge crests.

Snowpack Summary

In exposed high elevation terrain, recent moderate southerly winds and new snowfall have formed wind slabs in leeward features. At lower elevations and on sun exposed slopes, there is likely moist or wet snow sitting on top of several well bonded crust layers in the upper snowpack.

Avalanche Problems

Wind Slabs

Wind slabs have recently formed in north facing terrain at higher elevations and are expected to remain reactive to human triggering.

Be cautious as you transition into wind affected terrain.Use ridges or ribs to avoid pockets of wind loaded snow.Extra caution needed around cornices with current conditions.

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

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 2

Loose Wet

Watch for loose wet avalanches on steep south-facing slopes when the sun comes out.

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1 - 2