Avalanche Forecast

Issued: Jan 18th, 2017 4:35PM

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

Avalanche Canada mbender, Avalanche Canada

It will take a few days for the most recent storm snow to settle and bond. A cautious approach is recommended.

Summary

Confidence

Moderate - Forecast snowfall amounts are uncertain

Weather Forecast

THURSDAY: Cloudy with isolated flurries, accumulation 5-10cm, light to moderate southwest winds, Alpine temperature -7FRIDAY: Cloudy with isolated flurries, light southwest wind, alpine temperature -6SATURDAY: Mix of sun and cloud, wind light southeast, alpine temperature -8More details can be found on the Mountain Weather Forecast.

Avalanche Summary

A person walking at 600 metres elevation triggered a wind slab avalanche 100 cm deep running on a facet layer. It was 20 metres wide on a smooth north aspect that released a size 2.0 avalanche burying one person with just their hand exposed. The person was rescued by their companion. This happened in the Selkirks between Sale Mtn and Keystone Basin. Click here to see the MIN post. Recent reports indicate several natural avalanches to size 2.5 and 3. These avalanches were occurring on all aspects in the alpine and are isolated to the most recent storm snow. There were also a few skier controlled avalanches to size 2 releasing as a storm slab in the upper tree line elevation band. I would expect that skier and rider triggered avalanches will remain likely for the next few days as the storm snow gets a chance to settle and bond.

Snowpack Summary

Storm snow continues to develop storm slabs on all aspects and at all elevations. These new storm slabs are sitting on variable old surfaces that include surface hoar, and hard wind slabs. Before the storm, recent cold and clear weather had promoted both faceting of surface snow as well as the growth of surface hoar that has been reported to be up to 10mm in size in protected areas. Below this surface, our recent new snow was shifted first by southwesterly winds and then by northerly winds. As a result, buried wind slabs exist on a variety of aspects at upper elevations. A layer of faceted "sugar snow" and spotty surface hoar which formed during December's cold snap now lies roughly 1 metre below the surface. This layer is now dormant in many areas, but may still be a concern in shallow snowpack parts of the region, particularly around Clemina Creek. I'd continue to investigate this layer before committing to any large, unsupported features. The lower snowpack seems to be generally strong and well settled.

Problems

Storm Slabs

An icon showing Storm Slabs
New storm snow combined with strong southwest winds and warming temperatures have developed a touchy storm slab problem.
New snow will require several days to settle and stabilize.Watch for signs of instability such as whumpfing, or cracking. Be cautious as you transition into wind affected terrain.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

2 - 3

Valid until: Jan 19th, 2017 2:00PM

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