Avalanche Forecast

Issued: Dec 28th, 2016 5:29PM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is moderate. Known problems include Storm Slabs, Loose Dry and Persistent Slabs.

Avalanche Canada cgarritty, Avalanche Canada

The new snow keeps coming! A fresh dump on Thursday will keep avalanche danger elevated in the region.

Summary

Confidence

Moderate - Intensity of incoming weather systems is uncertain

Weather Forecast

Thursday: An incoming storm wave will deliver 15-20cm of new snow. Winds will be moderate gusting to strong from the southwest. Alpine temperatures to -8.Friday: Mainly cloudy with isolated flurries and a trace of new snow. Winds light gusting to moderate from the west. Alpine temperatures around -10.Saturday: Mainly cloudy with isolated flurries and a trace of new snow. Winds light from the south. Freezing level dropping to valley bottom and alpine temperatures to -12.

Avalanche Summary

At the time of publishing this bulletin, the only new avalanche observations have been related to sluffing of unconsolidated new snow. However, continued strong ridgetop winds along with new snow on Thursday will promote ongoing wind slab development and activity. For the short term, I also expect loose dry avalanches to be triggered easily in steep sheltered terrain.

Snowpack Summary

Up to 45 cm of new low density snow has fallen since Monday. In higher elevation terrain where the winds were stronger, I would expect new wind slab formation on lee and cross-loaded features. 65-100 cm below the surface you'll find the mid-December interface which consists of a variety of old snow surfaces including wind affected snow, faceted (sugary) crystals, and/or surface hoar crystals. Recent tests suggest the the new snow is well bonded to the interface in some areas. However, a few public and professional reports suggest this layer may be reactive in some areas and worth investigating before pushing into steeper terrain. The thick mid-November crust layer typically sits 1-2 m down in the snowpack. Recent test results on this layer suggest it is generally well bonded to the adjacent snow with the possible exception of shallow snowpack areas. This layer is considered dormant at this time but remains an isolated concern that we will likely be tracking through much of the season.

Problems

Storm Slabs

An icon showing Storm Slabs
Up to 60cm of new snow has fallen since Monday and more is on the way. Watch for signs like shooting cracks that tell you the storm snow is consolidating into a slab and expect conditions to be touchier in wind-exposed areas.
Be cautious as you transition into wind affected terrain.Avoids areas where the surface snow feels stiff or slabby.Be alert to conditions that change with elevation.

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

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2

Loose Dry

An icon showing Loose Dry
A lot of unconsolidated low-density snow has accumulated this week. Loose dry avalanches are a risk in gullies and other steep features that are sheltered from the wind.
Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.Use safe ski cutting techniques before entering steep features.Be cautious of sluffing in steep terrain.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2

Persistent Slabs

An icon showing Persistent Slabs
A mid-December weak layer has generated some isolated reports of large avalanches in the Columbia mountains to the south. This layer exists in the Cariboos as well, and may be easier to trigger in thin snowpack areas on the eastern edge of the range.
Dig down to find and test weak layers before committing to a line.Be aware of the potential for large avalanches due to the presence of buried persistent weak layers.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

1 - 3

Valid until: Dec 29th, 2016 2:00PM