Archived

Avalanche Forecast

Dec 12th, 2014–Dec 13th, 2014

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

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

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: Sea To Sky.

Although avalanche danger has decreased post-storm, take a cautious approach and gather your own snow pack information before committing to exposed terrain.

Confidence

Fair - Due to the number of field observations

Weather Forecast

Temperatures should stay cooler through the weekend, with a freezing level dropping to around 700 m. Any remaining snow flurries on Saturday should taper off by Sunday. Winds become light for the weekend.

Avalanche Summary

A natural cycle up to size 3 was observed throughout the recent storm. These included wind slabs and storm slabs, primarily at alpine elevations; and loose wet and wet slab avalanches at treeline and below. Some of these events failed on a crust /facet layer buried in late November and were more than 1 metre deep. On Thursday night a slab failed in terrain that had previously been controlled with explosives, 1.5-2m deep, with good propagation. Check the Whistler-Blackcomb avalanche advisory for more details.

Snowpack Summary

The recent prolonged storm dropped 100-200mm of water, with fluctuating freezing levels bringing rain at times to alpine elevations. Snow also accumulated above treeline, leading to deep wind slabs. Now the storm is over, storm slabs and wind slabs are likely to remain problematic for a day or two. However, my bigger concern is a buried crust/facet layer which formed in November and is now down 1-2m. This has woken up with storm snow loading and has the potential for deep slabs and wide propagations, and does not inspire huge confidence.

Avalanche Problems

Storm Slabs

Recent storm and wind slabs may be susceptible to human triggering, especially on the northwest through northeast side of terrain breaks. A storm slab could trigger a more deeply buried weak layer, causing a surprisingly large avalanche.

Use caution in lee areas in the alpine. Recent wind loading has created wind slabs. Avoid these features by traveling on ridge tops or ribs.>Avoid convexities or areas where the snowpack depth transitions from thin to thick.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 2 - 5