Archived

Avalanche Forecast

Jan 20th, 2017–Jan 21st, 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

1: Low

The avalanche danger rating at treeline will be low

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Regions: South Rockies.

The consequence of triggering a large persistent slab avalanche warrants a cautious approach to steep open terrain.

Confidence

Moderate - Due to the number of field observations

Weather Forecast

SATURDAY: Cloudy with sunny periods, light winds, alpine temperatures around -5 C.SUNDAY: Cloudy, light to moderate southeast winds, alpine temperatures around -7 C.MONDAY: Cloudy with isolated flurries, light to moderate east winds, alpine temperatures around -10 C.

Avalanche Summary

No new avalanches were reported on Friday. On Thursday, avalanche reports were limited to a size 1 skier-triggered wind slab on a steep convex below treeline feature.Wind slabs may remain possible to trigger in isolated locations over the weekend. The main concern continues to be the possibility of triggering the weak faceted layers deeper in the snowpack, although uncertainty revolves around what type of loading or weak spots are required for human triggering.

Snowpack Summary

Recent flurries and winds have formed hard wind slabs on lee features in exposed terrain, while warm temperatures have moistened the upper snowpack below treeline. The snowpack is quite variable throughout the region. In deeper snowpack areas, the snowpack appears to be well settled 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. Triggering a persistent slab in thinner snowpack area may result in a full depth avalanche.

Avalanche Problems

Persistent Slabs

Triggering deeper weak layers remains possible where hard slabs sit above weak sugary snow.

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

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Unlikely - Possible

Expected Size: 2 - 3

Wind Slabs

Recent flurries and winds have formed thin wind slabs.

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

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

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 2