Archived

Avalanche Forecast

Jan 9th, 2013–Jan 10th, 2013

Alpine

4: High

The avalanche danger rating in the alpine will be high

Treeline

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

3: Considerable

The avalanche danger rating below treeline will be considerable

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

3: Considerable

The avalanche danger rating below treeline will be considerable

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

2: Moderate

The avalanche danger rating below treeline will be moderate

Regions: South Columbia.

Confidence

Fair

Weather Forecast

Thursday: Light N wind. Alpine temperature near -11. No precipitation.Friday: Light NW wind. Alpine temperature near -12. No precipitation.Saturday: Light W wind. Alpine temperature near -14. Light snow.

Avalanche Summary

A widespread natural cycle of avalanches up to size 3 has been observed over the past two days. Many failed during rapid wind-loading on Tuesday night. Skiers have also been triggering numerous avalanches, including a size 2-2.5 slab which was triggered remotely from 30 m away. Many avalanches have been failing on surface hoar or facets below the storm snow.

Snowpack Summary

Deep storm snow overlies weak old snow surfaces including surface hoar (most prevalent at and below treeline), facets and sun crusts (found on some steep south to south-west aspects). There is a poor bond at this interface. In wind-exposed terrain, wind slabs and cornices have formed in the lee of ridges and ribs. Storm snow will take time to settle and stabilize, even after the weather improves and temperatures drop. A strong mid-pack overlies a weak facet/crust layer near the base of the snowpack.

Avalanche Problems

Storm Slabs

Deep storm snow is bonding poorly to the old snow surface. Large storm slabs remain possible, even after the weather improves.

Avoid open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.>Avoid exposure to overhead avalanche terrain, as large avalanches may reach the end of runout zones.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 1 - 5

Wind Slabs

Wind slabs have formed behind terrain breaks such as ridges and ribs. These could be triggered by the weight of a person or snowmobile and could be surprisingly large.

Stay off recent wind loaded areas until the slope has had a chance to stabilize.>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: Likely

Expected Size: 1 - 6