Avalanche Forecast

Issued: Mar 29th, 2018 4:12PM

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

Avalanche Canada mbender, Avalanche Canada

In the north of the region, newly formed win slabs may be sitting on a weak layer of facets or surface hoar on shady aspects in the alpine and tree line.

Summary

Confidence

Moderate - Due to the number of field observations

Weather Forecast

FRIDAY:  Mix of sun and cloud in the north. Mostly cloudy with isolated flurries in the south / Light to moderate west wind / Alpine temperature -2 / Freezing level 1400 m SATURDAY: Mix of sun and cloud / Light to moderate southeast wind / Alpine temperature -1 / Freezing level 1500 m SUNDAY: A mix of sun and cloud with isolated flurries / Light to moderate west wind / Alpine temperature -4 / Freezing level 900m

Avalanche Summary

On Tuesday there was report of a skier triggered wind slab from the north of the region in the alpine near ridge top running on a layer of facets buried March 21.Reports on Monday from the north of the region show several skier triggered and natural storm slab avalanches size 1.5 to 2.5 running on either facets or surface hoar on north through east aspects in the alpine and tree line.

Snowpack Summary

Last weekend's 20-40 cm of storm snow sits on a crust that is present at all elevations on solar aspects as well as low elevation northerly aspects. On northerly and east aspects at treeline and alpine elevations the storm snow sits on a mix of large surface hoar and or facets.Deeper in the snowpack in the north of the region, north and east aspects are harboring cold snow and a surface hoar layer buried early March that is about 40-60 cm below the surface. This layer exists at alpine and treeline elevations, but it is not everywhere. This layer has produced large human triggered avalanches in the north of the region in the past week. Also in the north of the region a weak layer buried mid-February is about 60 to 80 cm below the surface and has been reactive in snowpack tests. The layer is composed of sugary facets, a sun crust on solar aspects, and surface hoar that is present at and below tree line. In the south of the region, around the Coquihalla and in Manning Park, the recent storm snow overlies a recent crust that caps a well settled snowpack.

Problems

Storm Slabs

An icon showing Storm Slabs
Moderate to strong southwest winds have built wind slabs. These slabs seem to be most reactive in the north of the region, specifically on shady aspects where they may be sitting on a layer of weak facets or surface hoar.
Use ridges or ribs to avoid pockets of wind loaded snow.Be cautious as you transition into wind affected terrain.Watch for whumpfing, hollow sounds, and shooting cracks.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Mar 30th, 2018 2:00PM

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