Archived

Avalanche Forecast

Mar 22nd, 2013–Mar 23rd, 2013

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

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

1: Low

The avalanche danger rating below treeline will be low

Regions: South Coast.

Avalanche danger may spike on slopes receiving direct sun. Avoid travelling on or underneath sun-baked terrain.

Confidence

Fair - Timing or intensity of solar radiation is uncertain

Weather Forecast

Saturday-Monday: Mainly sunny with a few clouds and light winds. Alpine temperatures near -5, dropping overnight.

Avalanche Summary

On Thursday, wind slabs were triggered naturally and by skiers in the size 1.5-2 range, mainly on NE aspects at treeline and above. Skiers also triggered small storm slabs which failed on a buried crust. On Wednesday, a widespread natural cycle was observed, with avalanches to size 2.5 failing with solar warming. Cornice fall was also occurring.

Snowpack Summary

The snowpack is variable across the region. Recent storm snow has been redistributed by mainly SW winds into wind slabs over various crust layers in the upper snowpack. In some areas, a melt-freeze crust down about 35 cm has a questionable bond with the snow above. Surface hoar, buried down about 50-70 cm, gave hard, sudden (pops) results in recent snowpack tests. Triggering this layer has become less likely, but still remains possible with a heavy load or from a thin-spot trigger point. Cornices are large and unstable in some areas. Warm temperatures may weaken them further.

Avalanche Problems

Wind Slabs

Wind slabs may be lurking behind ridges and ribs and in cross-loaded gully features.

Be cautious as you transition into wind affected terrain.>Travel on ridgetops to avoid wind slabs on slopes below.>

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

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 4

Persistent Slabs

Avalanches failing on a crust and/or surface hoar layer buried about 50-70 cm down are becoming less likely, but could be triggered with a heavy load, or from a thin or convex-shaped part of a slope.

Choose well supported terrain without convexities.>Be aware of thin areas that may propagate to deeper instabilites.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible

Expected Size: 2 - 6

Cornices

Cornices are reported to be large and may become unstable with mild temperatures and sunny periods. Cornice fall could trigger a slab on the slope below.

Do not travel on slopes that are exposed to cornices overhead.>Stay well to the windward side of corniced ridges.>

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

Elevations: Alpine.

Likelihood: Possible

Expected Size: 3 - 6