Avalanche Forecast

Issued: Jan 11th, 2018 3:49PM

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

Avalanche Canada mconlan, Avalanche Canada

Watch for touchy wind slabs at all elevations created from strong outflow winds.

Summary

Confidence

Moderate - Due to the number of field observations

Weather Forecast

FRIDAY: Increasing cloudiness over the day with light snowfall starting in the afternoon, accumulation 10-20 cm overnight, strong outflow winds, alpine temperature near -10 C, freezing level below valley bottom.SATURDAY: Cloudy with light snowfall, accumulation 5 to 10 cm, light to moderate southerly winds, alpine temperature rising to 0 C but cold in the valleys, freezing level near 1800 m with inversion conditions.SUNDAY: Cloudy with light precipitation, accumulation 5-10 mm, moderate southerly winds, alpine temperature near 4 C but possible cold air in the valleys, freezing level near 2000 m with inversion conditions.

Avalanche Summary

A small naturally triggered wind slab was observed on a southerly aspect on Thursday.  More avalanches are likely with continuing strong outflow winds.

Snowpack Summary

The snowpack is variable across the region. Wind slabs and storm slabs are found on some slopes in the alpine and at treeline.  Strong outflow winds have formed wind slabs on southerly and southwesterly lee features at all elevations.Up to 45 cm recent snow overlies several layers of interest in the upper snowpack. These include crusts, surface hoar and facets. A hard crust with associated facets from mid-December sits deeper in the snowpack, about 60 cm down. Any of these layers could create a persistent slab problem if new snow, wind-loading or warming change the properties of the slab above.The lower snowpack is generally strong, with the exception of areas around Stewart and further north where a basal crust and facets exist.

Problems

Wind Slabs

An icon showing Wind Slabs
Strong outflow winds have created stiff wind slabs.  Wind slabs formed from the last storm may also linger in lee features.  If triggered, these slabs may step down to buried weak layers and form large avalanches.
Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.Travel on ridgetops to avoid wind slabs on slopes below.

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

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Jan 12th, 2018 2:00PM

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