Avalanche Forecast

Issued: Jan 7th, 2017 4:48PM

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

Avalanche Canada cgarritty, Avalanche Canada

New snow combined with sustained winds will keep our wind slab problem alive and well. Even if the rating is still Moderate, stability will be decreasing as new snow piles up.

Summary

Confidence

Moderate - Timing of incoming weather systems is uncertain on Sunday

Weather Forecast

Sunday: Flurries with 5-10cm of new snow arriving late in the day. Winds light to moderate from the southwest. Alpine temperatures around -5.Monday: Cloudy with scattered flurries and 4-7 cm of new snow. Winds light gusting to strong from the southwest. Freezing level to 900 metres with alpine temperatures of -4.Tuesday: A mix of sun and cloud with a trace of new snow. Winds light to moderate from the northwest. Freezing level to valley bottom with alpine temperatures of -8.

Avalanche Summary

A Size 1 wind slab avalanche was triggered by a skier in the Valhalla range on Thursday. The slide had a crown depth of approximately 30 cm and ran on a steep north aspect above 2000 metres in elevation. This serves as a good reminder that the wind slab problem hasn't disappeared yet and that it can be found on north aspects too. No new natural avalanches were reported today, but you can expect our new snow to sluff easily in steep terrain.

Snowpack Summary

Approximately 5 cm of new snow fell over Thursday night, covering facets and surface hoar which formed throughout the region during cold, dry weather earlier this week. On steep solar (south) aspects, a breakable sun crust may exist below the new snow. Recent cold temperatures have been promoting faceting, especially in the upper snowpack. The last snow we received (30-60 cm) was exposed to east through northerly winds during the cold clear period. While many areas saw "reverse loading" of the storm snow into wind slabs on south to west aspects, local wind patterns have seen slabs form on a wide range of aspects. Snowpack testing of various wind slabs continues to yield moderate to hard results with sudden fracture character. Below the wind slabs and storm snow, the weak layer buried on Boxing Day appears to have formed a good bond to the snow above. 50-70 cm below the surface we have another weak layer buried on December 18. This layer appears to be well bonded in most parts of the region, giving moderate results in snowpack tests, but not expected to be reactive to skier loads.

Problems

Wind Slabs

An icon showing Wind Slabs
Recent winds formed slabs behind exposed terrain features and especially on southwest to north aspects. New snow with wind on Sunday will form fresh slabs and require backcountry travelers to manage both old and new windslabs on any given aspect.
Use ridges or ribs to avoid pockets of wind loaded snow.Watch for stability to deteriorate over the day.Use caution in lee areas. Forecast snow and wind will be forming wind slabs.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Jan 8th, 2017 2:00PM

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