Archived

Avalanche Forecast

Dec 19th, 2014–Dec 20th, 2014

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

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

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

Regions: Purcells.

New snow, strong winds and rising temperatures make a good recipe for rising avalanche danger over the next few days.

Confidence

Fair - Intensity of incoming weather systems is uncertain

Weather Forecast

Expect light to locally moderate snow from Saturday to Monday. Temperatures rise towards 0 at 1500m by Saturday. Winds are expected to be moderate to strong from the west to south-west throughout the period.

Avalanche Summary

On Thursday and Friday, explosive control produced several size 1-2 slabs. These slabs were around 20cm thick. In the Dogtooth area, these failed on reloaded bed surfaces (early November rain crust/facet layer). A size 2.5 naturally-triggered slab was observed at 2600m on an east aspect on Friday.

Snowpack Summary

New snow sits on variable surfaces including wind-affected snow, surface hoar and a crust which exists below about 2200m. Winds are expected to shift new snow onto lee slopes over the next couple of days. A thick rain crust with facets from early November is buried over 1 m down and may still be reactive in isolated areas. A weak layer from the end of November sits in the middle of the snowpack and is still reactive in some areas.

Avalanche Problems

Storm Slabs

Storm snow is expected to be shifted by winds into slabs on lee slopes. In more sheltered areas, loose snow avalanches may be encountered in steep terrain. The new snow sits above a weak layer of buried crystals in some locations.

Avoid freshly wind loaded features by sticking to ridges and ribs.>Be cautious of sluffing in steep terrain.>Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 2

Deep Persistent Slabs

There is still the potential to trigger a deeply buried weak layer, resulting in a surprisingly large avalanche.

Remote triggering is a concern, watch out for adjacent slopes.>Avoid common trigger zones including thin snowpack areas, near rocky outcrops, and steep alpine slopes.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 2 - 5