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Avalanche Forecast

Dec 31st, 2018–Jan 1st, 2019
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.

Strong wind from variable directions have set up a complicated pattern of wind-affected slopes in exposed areas.

Confidence

High -

Weather Forecast

MONDAY NIGHT: Mostly clear skies, moderate northwest winds, freezing level below valley bottom.TUESDAY: Mix of sun and clouds, moderate northwest winds, alpine temperature -10 C, freezing level below valley bottom.WEDNESDAY: Mix of sun and clouds, moderate to strong west winds, alpine temperature -10 C, freezing level below valley bottom.THURSDAY: Cloudy with light snowfall, strong southwest winds, alpine temperature -5 C, freezing level rising to 1500 m.

Avalanche Summary

No new avalanches were observed on Monday. Several loose dry avalanches and a few small (size 1) storm slab avalanches were triggered (ski cut) in this region on Sunday.

Snowpack Summary

The upper snowpack consists of hard wind slabs on north aspects, scoured and a shallower snowpack on south aspects, and a mixed bag of lower density snow in more sheltered areas. In total, 60-90 cm of December snow has formed a slab that sits on a persistent weak layer of facets (sugary snow) that formed during the dry weather in early December. This layer is most likely to be triggered on steep features where the underlying ground cover is smooth, areas where the snowpack depths are variable, or on large convex features.The lower snowpack has a weak structure composed primarily of facets over a crust on the ground. It is very likely that an avalanche triggered on the persistent slab would step down to the lower facets, resulting in a full depth avalanche.

Avalanche Problems

Wind Slabs

Strong winds have set up wind slabs in exposed areas. Winds initially blew from the southwest and then switched to the northwest making for a potentially complicated wind-loaded pattern.
If triggered the wind slabs may step down to deeper layers resulting in large avalanches.Be cautious as you transition into wind affected terrain.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 2

Deep Persistent Slabs

60-90 cm of snow sits on a weak layer of sugary facets. The snow below this layer consists primarily of weak facets all the way to the ground. Avalanches triggered on this layer will likely scour to the ground, resulting in large avalanches.
Watch for whumpfing, hollow sounds, and shooting cracks.Be wary of slopes that did not previously avalanche.Avoid steep slope angles or areas with a thin or variable snowpack.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 2 - 2.5