Avalanche Forecast

Issued: Jan 15th, 2019 4:00PM

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

jfloyer, Avalanche Canada

Northwest Coastal.

Danger will be highest on slopes that face the sun and where winds have recently blown the snow into slabs. Expected outflow winds could locally increase avalanche danger.

Summary

Confidence

Moderate - Wind speed and direction is uncertain

Weather Forecast

TUESDAY NIGHT: Dry with clear spells. Cooling.WEDNESDAY: Dry with a mix of sun and cloud. Treeline temperatures around -5C. Easterly outflow winds are expected at 1300 m and below in large valleys that drain towards the west; in other areas winds are expected to be light.THURSDAY: Dry with a mix of sun and cloud. Treeline temperatures around -8C. Easterly outflow winds continuing.FRIDAY: Dry with cloud increasing through the day. Treeline temperatures around -8C. Moderate southeasterly winds.

Avalanche Summary

Storm slab avalanches up to size 3 continued to be reported into Sunday due to the warm and wet storm that has affected this region. Storm and wind slabs are likely gaining strength, except on slopes facing the sun and where wind effect is pronounced.An avalanche incident was reported in the Shames backcountry area last Thursday. The incident involved two skier triggered avalanches occurring in succession with two people involved and partially buried. The details can be found on the Mountain Information Network. (here) An very large (size 3.5) natural avalanche occurred in the north of the region on Sunday that is believed to have initiated on a buried layer of surface hoar then stepped down to the weak layer from early December.

Snowpack Summary

A warm and wet storm brought up to 100 mm precipitation between Wednesday and Sunday last week, with rain falling as high as 1500 m. Precipitation has now ended and temperatures have started to cool. New snow from the storm is likely to have blown into wind slab deposits at higher elevations. The snow is crusty at lower elevations.In some sheltered areas the new snow is sitting on a weak layer of surface hoar (feathery crystals). For most of the region, a weak layer of facets (sugary snow) buried in early December exists down 180-250 cm. The likelihood of triggering this layer is decreasing, but it could be triggered by humans in shallow snowpack areas, particularly in the north of the region. The potential may also exist for storm slab avalanches to step down to this layer, resulting in large avalanches.

Problems

Wind Slabs

Wind slabs from the previous storm exist on north to east aspect. Outflow winds blowing from the east may set up new wind slabs on westerly aspects where new snow is available for wind transport.

Avoid freshly wind loaded features, especially near ridge crests, roll-overs and in steep terrain.Minimize exposure to steep, sun exposed slopes when the solar radiation is strong.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1.5 - 2.5

Valid until: Jan 16th, 2019 2:00PM