Avalanche Forecast

Issued: Dec 26th, 2016 4:56PM

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

jlammers, Avalanche Canada

Cariboos.

Tuesday's snowfall amounts will likely vary throughout the region. In areas that receive more than 20cm of new snow, the Avalanche Danger may be higher than posted.

Summary

Confidence

Moderate - Forecast snowfall amounts are uncertain on Tuesday

Weather Forecast

Tuesday: 10-20cm of new snow / Strong westerly winds / Freezing level at valley bottomWednesday: Overcast skies / Moderate westerly winds / Freezing level at Valley bottomThursday: Light flurries / Moderate westerly winds / Freezing level at Valley bottom

Avalanche Summary

No new avalanches have been reported. With new snow and strong winds forecast for Monday night and Tuesday, I'd expect new wind slab activity in higher elevation terrain on Tuesday.

Snowpack Summary

On Tuesday, new snow and wind are forecast to form fresh wind slabs in exposed higher elevation terrain. 50-80 cm of snow now overlies 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 recent Mountain Information Network report from the Clearwater area suggests this layer may be reactive 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

New snow and wind forecast for Monday night and Tuesday will form new wind slabs in exposed higher elevation terrain.

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.

Elevations: Alpine, Treeline.

Likelihood

Likely - Very Likely

Expected Size

1 - 2

Persistent Slabs

A weak layer buried mid-December now lies up to 70cm 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.

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

Possible

Expected Size

1 - 3

Valid until: Dec 27th, 2016 2:00PM