Avalanche Forecast

Issued: Jan 17th, 2014 8:38AM

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

jfloyer, Avalanche Canada

Northwest Coastal.

Summary

Confidence

Fair - Intensity of incoming weather systems is uncertain

Weather Forecast

A fast moving front will spread some precipitation Friday night and Saturday before the ridge of high pressure rebuilds on Sunday..Saturday: 10-15 cm new snow expected with freezing levels around 1000 m. Ridgetop winds 50-70 kméh from the south.Sunday and Monday: Dry, with a mix of sun and cloud. Freezing levels around 800 m. Winds light southwesterly.

Avalanche Summary

There was an avalanche cycle the ended on Wednesday producing avalanches up to size 4 on all elevation and on all aspects. Most of these avalanches ran on the early January surface hoar layer buried under the storm snow at treeline and below treeline; some of the larger ones ran on the deep persistent basal facet layer in the alpine in the Northern part of the region.

Snowpack Summary

Recent warm temperatures have settled the recent storm snow that ended around 13-14th January, which was previously very reactive on a layer of surface hoar (particularly between 900 and 1400 m) buried around 1 m deep. Weak basal facets near the base of the snowpack were also reactive during this time, particularly in the north of the region. These are found in the alpine and at treeline under over 2 m of snow in some areas. The deep persistent layer at the base of the snowpack is also found in the Southern part of the region, but appears to be less reactive.Extensive wind slab formed on lee and cross-loaded slopes during the SW winds associated with the last storm.

Problems

Deep Persistent Slabs

A weak layer of facets/depth hoar at the base of the snowpack has been responsible for some recent very large avalanches. The likelihood of triggering this layer is now considerably reduced, but the consequences associated with this layer are huge.

Avoid convexities or areas with a thin or variable snowpack.>Be aware of the potential for large, deep avalanches.>Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

4 - 7

Storm Slabs

New snow and wind will likely set up reactive slabs, especially in lee and cross-loaded terrain in the alpine. Given the recent history of large avalanches, there is a chance that a small avalanche triggered near the surface could step down.

Avoid freshly wind loaded features.>Minimize overhead exposure; avalanches triggered by windloading may reach run out zones.>

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

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 4

Valid until: Jan 18th, 2014 2:00PM