Archived

Avalanche Forecast

Mar 13th, 2012–Mar 14th, 2012

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

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.

Confidence

Fair - Due to variable snowpack conditions

Weather Forecast

Wednesday: light snowfall - light southeast winds - freezing level at 600m Thursday: moderate snowfall - light to moderate south winds - freezing level at 900m Friday: light snowfall - light to moderate southwest winds - freezing level at 700m

Avalanche Summary

A few natural slab avalanches to size 2 occurred in response to recent wind loading in the north of the region. They occurred on steep, lee slopes behind ridges or cornices.

Snowpack Summary

Light amounts of low density snow sit over a variety of old surfaces that include widely distributed hard wind slabs, or melt freeze crusts that exist on most aspects below 1000m and on solar aspects as high as 1600m. In exposed areas the newer low density snow has been shifted into stiffer pockets of soft wind slab. The mid February interface, down around 60cm, is variable and generally consists of a strong melt freeze crust below 1000m. Above that elevation, expect to find buried facets, and/or surface hoar (in more sheltered areas), and/or a sun crust on southern aspects. The surface hoar is not widespread and is gaining strength, but should still be on your radar in steeper, unsupported terrain at treeline and below. Cornices in the area are also reported to be very large and primed for triggering.

Avalanche Problems

Wind Slabs

Fresh windslabs may exist on lee slopes adding to a strengthening, yet widespread hard wind slab problem that developed last week.

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

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 4

Cornices

Large cornices exist in alpine terrain. A failure could be destructive by itself, and could also trigger an avalanche on the slope below.

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

Elevations: Alpine.

Likelihood: Possible

Expected Size: 1 - 5

Persistent Slabs

The persistent weak layer that formed in early February is most prominent on unsupported, sheltered slopes at treeline . Although avalanches on this layer have not been reported this week, triggering may still be possible in isolated terrain.

Aspects: All aspects.

Elevations: Alpine.

Likelihood: Possible

Expected Size: 3 - 5