Archived

Avalanche Forecast

Dec 17th, 2012–Dec 18th, 2012

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

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

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

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 Coast.

Confidence

Fair - Timing, track, or intensity of incoming weather is uncertain on Wednesday

Weather Forecast

Tuesday: Light SW winds. Alpine temp -15. A few cm snow.Wednesday: Strong to gale S winds. Alpine temp -10. Moderate snow (~20 cm).Thursday: Moderate S winds. Alpine temp -9. Light snow.

Avalanche Summary

Size 1-2 sluffs were running in steep terrain on Sunday and skiers were triggering numerous size 1 soft wind slabs on lee features. A skier also triggered a size 1.5 soft slab at treeline, which failed on a layer of stellars and surface hoar down 30 cm in the Duffey Lake area.

Snowpack Summary

Low density storm snow has been shifted by variable winds into soft slabs in the alpine and at treeline. A layer of surface hoar and stellars buried on Dec 10 exists at treeline in the Duffey Lake area and may be more widespread. Recent snowpack tests produced hard to no results on a deeper surface hoar layer from late November, buried down 70-100 cm. A consolidated mid-pack overlies the deeply buried November crust/facet layer, which gives occasional sudden planar compression test results. This layer has not been observed in the Coquihalla area.

Avalanche Problems

Storm Slabs

Weaknesses within and below the storm snow will need some time to settle and bond. Be alert for wind slabs behind ridges and terrain breaks.

Stay off recent wind loaded areas until the slope has had a chance to stabilize.>Be cautious of sluffing in steep terrain.>Avoid open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible - Likely

Expected Size: 1 - 5