Archived

Avalanche Forecast

Jan 11th, 2013–Jan 12th, 2013

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

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

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

2: Moderate

The avalanche danger rating below treeline will be moderate

Regions: South Columbia.

Conditions will be tricky to manage this weekend, as a touchy surface hoar layer is buried only on some slopes and not others. Make constant snowpack assessments as you travel and take a cautious approach to terrain selection.

Confidence

Fair - Due to variable snowpack conditions

Weather Forecast

Saturday: Light W wind. Alpine temperature near -14. No snow.Sunday: Light N wind. Alpine temperature near -15. No snow.Monday: Light NW wind. Alpine temperature near -8. Light snow.

Avalanche Summary

A natural cycle of size 1-3 storm slabs occurred over the last few days. Skiers also several avalanches up to size 2, failing on buried surface hoar or facets. We are now moving into a period when natural activity is likely to decrease, but human-triggering will remain a concern.

Snowpack Summary

50-90 cm of recent snow is settling into slabs above old snow surfaces including surface hoar (found especially at and below treeline in sheltered areas), a sun crust (on steep S to SW-facing slopes) and facets. The distribution of buried surface hoar is patchy, but where it does exist, it is touchy, with widespread propagation and remote-triggering occurring. Recent winds have left wind slabs in the lee of terrain breaks such as ridges and ribs at alpine and treeline elevations. In areas sheltered from the wind, fast-moving sluff could throw you off your feet or carry you into a terrain trap. A strong mid-pack overlies a weak facet/crust layer near the base of the snowpack, which is now considered inactive.

Avalanche Problems

Persistent Slabs

Storm snow is particularly reactive where it overlies buried surface hoar. This weakness may be triggered from a distance and avalanches could be surprisingly large.

Be wary of slopes that did not previously avalanche - even on low angle terrain.>Remote triggering is a concern, watch out for adjacent slopes.>Avoid open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 6

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.

Be cautious as you transition into wind affected terrain.>Use ridges or ribs to avoid pockets of wind loaded snow.>Avoid steep slopes below cornices.>

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

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 5