Avalanche Forecast

Issued: Dec 21st, 2016 4:48PM

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

Avalanche Canada mbender, Avalanche Canada

As this past week's storm snow continues to settle it will still be important to evaluate the bond between the old snow surface and the new snow. There is still potential for a weak sliding layer in isolated sheltered areas.

Summary

Confidence

Moderate - Forecast snowfall amounts are uncertain

Weather Forecast

Thursday: Flurries, accumulation 5-10cm / Moderate southwest wind / Alpine temperature -4Friday: Mainly cloudy with isolated flurries / Light northeast wind / Alpine temperature -7Saturday: Sunny with cloudy periods/ Light north wind / Alpine temperature -10

Avalanche Summary

Recent reports from Monday and Tuesday indicate numerous explosive and a few skier triggered storm slab and wind slab avalanches to size 2 in the alpine and treeline at the storm snow/old snow interface . There were also reports of a few remotely triggered avalanches from thin wind scoured ridge crests into adjacent steeper loaded slopes. I would suspect there to be continued potential for skier and rider triggering with some recent very strong winds at upper elevations and a possible weak bond at the storm/old snow interface with buried surface hoar in isolated sheltered areas.

Snowpack Summary

30-50cm of new snow overlies the previous variable snow surface from last week, which includes hard wind pressed or scoured areas, old wind slabs, weak faceted snow, or surface hoar. Moderate to strong southwest wind has redistributed this new snow to form windslabs in the lee of terrain features in the alpine and treeline. The widespread mid-November crust is typically down 1-2m in the snowpack. Recent snowpack and explosive tests have shown the crust to be unreactive, but it could remain a problem in shallow alpine start zones.

Problems

Wind Slabs

An icon showing Wind Slabs
Recent strong southwest winds have created touchy wind slabs in the lee of terrain features
Use ridges or ribs to avoid pockets of wind loaded snow.Be cautious as you transition into wind affected terrain.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Storm Slabs

An icon showing Storm Slabs
Recent new snow sits on top of a variety of potential weak sliding layers.
Dig down to find and test weak layers before committing to a line.Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Dec 22nd, 2016 2:00PM