Archived

Avalanche Forecast

Jan 19th, 2017–Jan 20th, 2017

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: South Rockies.

The shallow weak snowpack continues to be a concern for triggering large avalanches.

Confidence

Moderate - Wind speed and direction is uncertain

Weather Forecast

FRIDAY: Cloudy with sunny periods, moderate west winds easing throughout the day, freezing level around 1200 m.SATURDAY: Mix of sun and cloud, light southwest winds, freezing level around 1000 m.SUNDAY: Cloudy with isolated flurries, light south winds, freezing level around 800 m.

Avalanche Summary

On Thursday, avalanche reports were limited to a size 1 skier triggered wind slab on a steep convex below treeline feature. We continue to be concerned about triggering the weak faceted layers in the snowpack, and our uncertainty revolves around what type of loading or weak spots are required for human triggering.

Snowpack Summary

Recent flurries and winds have formed thin wind slabs on lee features in exposed terrain at all elevations. The lower snowpack is quite variable throughout the region and the structure depends on snow depth. In deeper snowpack areas, the snowpack appears to be well settled and right side up with isolated concerns about the mid-December facet layer buried 50 to 100 cm deep. In shallow snowpack areas and lower elevations, the snowpack is heavily faceted. If a persistent slab is triggered from thinner snowpack areas it may release on basal facets resulting in a full depth avalanche.

Avalanche Problems

Persistent Slabs

Triggering deeper weak layers will remain possible with warm temperatures and wind loading.

Danger exists where denser snow overlies weak, sugary snow below.Be aware of the potential for full depth avalanches due to deeply buried weak layers.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible

Expected Size: 2 - 3

Wind Slabs

Recent flurries and winds have formed fresh wind slabs. Wind slab avalanches in motion may step down and trigger deep persistent slab avalanches.

Avoid areas where the surface snow feels stiff or slabby.Use ridges or ribs to avoid pockets of wind loaded snow.Be cautious as you transition into wind affected terrain.

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

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 2