Avalanche Forecast

Issued: Jan 31st, 2017 4:58PM

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

Avalanche Canada swerner, Avalanche Canada

Watch for changing conditions at higher elevations and be cautious around shallow snowpack areas where wind slabs could step down to deeper weak layers.

Summary

Confidence

High - The weather pattern is stable

Weather Forecast

A high pressure system sits over the Interior resulting in a fairly benign weather pattern until Friday. Wednesday/ Thursday: Clear skies with alpine temperatures near -11 and light easterly winds and freezing levels in the valley bottom. Friday: Cloudy with new snow amounts 8-15 cm. Alpine temperatures near -6 with ridgetop winds light from the southeast.

Avalanche Summary

On Monday, several size 2 wind slab avalanches were skier triggered in the lee of ridgetops and a natural cornice failure was able to entrain mass on the slope below but did not pull a slab. Also reported on Monday was  a significant large natural avalanche (size 2.5) on a wind-loaded east facing slope in the Rossland range. This avalanche likely released on a deeper persistent weak layer.Expect wind slabs to linger on lee and crossloaded features at higher elevations.

Snowpack Summary

A variety of surface conditions exist including wind effected snow, sun crusts and surface hoar. Up to 50cm of settled snow now sits above an interface that was buried in mid-January. The interface is composed of facets, surface hoar, and/or sun crusts and the strength of this interface is reportedly variable. Recent snowpack tests have shown sudden results on that interface. Areas with thin snowpacks (e.g. less than 150 cm) have a generally weak snowpack structure with sugary facets near the ground. This includes shallow alpine slopes and most of the Rossland range. These deeper weaknesses warrant monitoring and create a complicating picture especially when it comes to terrain selection and decision making. These layers may sit dormant now with this stable weather pattern but they could reawaken with a change.

Problems

Wind Slabs

An icon showing Wind Slabs
Watch for pockets of wind slabs on exposed features near ridge crests and cross-loaded gullies. Also be cautious around thin rocky areas where wind slabs could 'step down' to deeper weak layers.
Avoid convexities or areas with a thin or variable snowpack.Use ridges or ribs to avoid pockets of wind loaded snow.Avoid steep convexities or areas with a thin or variable snowpack.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Feb 1st, 2017 2:00PM

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