Avalanche Forecast

Issued: Dec 27th, 2016 4:16PM

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

jlammers, Avalanche Canada

Cariboos.

Winds will play a large role in driving the avalanche danger on Wednesday as there's lots of loose snow available for redistribution. Use extra caution if the snow feels stiff or slabby.

Summary

Confidence

Moderate - Due to the number of field observations

Weather Forecast

Wednesday: Light flurries / Strong westerly winds / Alpine temperatures of about -13Thursday: About 10cm of new snow / Strong southerly winds / Alpine temperatures of about -10Friday: Light flurries / Moderate westerly winds / Alpine temperatures of about -12

Avalanche Summary

No new avalanches were reported at the time of publishing this bulletin. I'm sure there was some natural wind slab activity in response to new snow and wind on Monday night. Continued strong ridgetop winds should promote ongoing wind slab activity. For the short term, I also expect loose dry avalanches to be triggered easily in steep sheltered terrain.

Snowpack Summary

By Tuesday morning, up to 35 cm of new low density snow had fallen. In higher elevation terrain where the winds were stronger, I would expect new wind slab formation on lee and cross-loaded features. 60-90 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

Wind Slabs

Up to 35 cm of new snow fell on Monday night. In higher elevation terrain where the winds were stronger, these accumulations may have been shifted into much deeper and potentially reactive wind slabs.

Be alert to conditions that change with elevation.Avoids areas where the surface snow feels stiff or slabby.Be cautious as you transition into wind affected terrain.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2

Persistent Slabs

A weak layer buried mid-December now lies up to 80cm below the surface and has the potential for large avalanches. It's a tricky one to manage as it's not a problem in all areas. If in doubt, err on the side of caution and to stick to mellow terrain.

Be aware of the potential for large avalanches due to the presence of buried persistent weak layers.Dig down to find and test weak layers before committing to a line.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

1 - 3

Loose Dry

With all the unconsolidated low-density snow that has accumulated, I'd be on the look out for loose dry avalanches in gullies and other steep features that were sheltered from the wind.

Be cautious of sluffing in steep terrain.Use safe ski cutting techniques before entering steep features.Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2

Valid until: Dec 28th, 2016 2:00PM