Archived

Avalanche Forecast

Dec 20th, 2014–Dec 21st, 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: Northwest Inland.

Strong winds and new snow have resulted in Considerable avalanche danger. If you see more snow than forecast in your area, consider these danger ratings to be a bit low.

Confidence

Poor - Timing, track, or intensity of incoming weather system is uncertain

Weather Forecast

Moderate Southerly winds overnight with a 2-3 cms of new snow and freezing levels at valley bottoms. Overcast with a 2-3 cms of new snow during the day on Sunday. Cooler and drier on Monday with moderate Westerly winds. The next pulse of moisture is expected on Tuesday.

Avalanche Summary

There are no new avalanche reports from the region. The forecast new storm is expected to develop a new storm slab that may increase avalanche activity.

Snowpack Summary

The new storm is expected to develop a storm slab above the dusting of new snow which overlies weak surface hoar reported to exist up to at least treeline elevation. Below the new snow you'll likely find wind-scoured surfaces and old wind slabs in exposed terrain, and settled storm snow closer to treeline. Near the base of the snowpack, weaknesses such as the mid-November crust-facet layer are still of concern. I'd use extra caution around steep, unsupported high elevation terrain as avalanches at this interface could propagate over wide distances.

Avalanche Problems

Storm Slabs

The new storm slab continues to develop. Snowfalls have been lower than forecast resulting in less avalanche activity than expected. Strong winds have transported snow into windslabs at higher elevations.

Use ridges or ribs to avoid wind loaded and cross loaded slopes.>Be cautious as you transition into wind affected terrain.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 3

Deep Persistent Slabs

Deeply buried weak layers may release during periods of high loading from new snow and wind. Deeply buried crusts are more likely to be triggered from shallow areas where boulders or trees are at or near the surface.

Avoid convexities or areas with a thin or variable snowpack.>Be aware of thin areas that may propogate to deeper instabilites.>

Aspects: All aspects.

Elevations: Alpine.

Likelihood: Unlikely - Possible

Expected Size: 2 - 4