Avalanche Forecast

Issued: Jan 16th, 2014 8:28AM

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.

Avalanche Canada slemieux, Avalanche Canada

Summary

Confidence

Fair - Timing or intensity of solar radiation is uncertain

Weather Forecast

Tonight and Friday: The whole Coast is under a high pressure system and the front affecting the Northern part of the region should move out tonight. Light precipitation will end tonight North of Stewart, the dry trend continues in the South. Moderate to strong wind from the SW will switch from the S. Temperatures will rise as well as freezing levels up to 3000 m (or 2000 m further North) with a mix of sun and clouds during the day.Saturday: A weakening frontal system will reach the coast which should bring moderate precipitation and strong S winds switching from the SW in the afternoon. Freezing levels are expected to lower to 1400 m. with the arrival of the snow.Sunday: Ridge of high pressure rebuilds over the coast leading to a clearing trend with mild temperatures.

Avalanche Summary

There was an avalanche cycle yesterday at all elevation and on all aspects. Multiple natural releases up to size 4.0.  Most of these avalanches would have run on the early January surface hoar layer buried under the storm snow at treeline and below treeline in all the region and some on the deep persistent basal facet layer in the alpine in the Northern part of the region.

Snowpack Summary

The increased solar radiation and warming trend for tomorrow is driving the avalanche danger. The intense heat will weaken the surface of the snowpack and most likely increase avalanche activity on all aspects, but especially on S and SE aspects slopes when the sun comes out. There is a possibility that loose wet or slabs could step down to deeper instability, especially in the Northern part of the region.In the North, the early January surface hoar buried at around 1 m deep at treeline and below treeline is showing to be a main concern since it has proved to be very active during the last storm, even on low angled terrain. The basal facets also became reactive in the last rapid loading. These are found in the alpine and at treeline under over 2 m of snow in some areas. The persistent weak layers mentioned above are also found in the Southern part of the region,but are not showing as much reactivity.  The extensive windslab formation that happened during the SW wind event have most likely started to bond to the underlying surface in the alpine and at treeline. However, expect steep crossloaded or steep lee features to weaken during the day especially if the sun hits those slopes.

Problems

Deep Persistent Slabs

An icon showing Deep Persistent Slabs
The basal facets layers are gaining strength in the S part of the region but are still reactive in the N. Warming and solar radiation will weaken the snowpack and cornices. Wet loose, slab avalanche or cornice drop could trigger this very deep layer.
Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.>Be aware of the potential for large, deep avalanches.>Avoid convexities or areas with a thin or variable snowpack.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

4 - 7

Storm Slabs

An icon showing Storm Slabs
The settling storm snow and windslabs could weaken tomorrow especially if they get strong solar radiation tomorrow. Expect loose wet avalanches especially on S and SE aspects.
Minimize exposure to sun exposed slopes when the solar radiation is strong.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 4

Valid until: Jan 17th, 2014 2:00PM