Avalanche Forecast

Archived

Nov 29th, 2022–Nov 30th, 2022

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Regions

Northwest Coastal, Kitimat, Nass, Rupert, Seven Sisters, Shames, Stewart, Howson, Ningunsaw.

Be cautious as you transition into wind-affected terrain. Easterly outflow winds have started to form fresh wind slabs in unusual areas and at lower elevations than is typical.

Cold temperatures, short days, and early season hazards should factor into your trip planning. Be prepared for an emergency and leave yourself plenty of daylight to get home safely.

Confidence

Moderate

Avalanche Summary

During last week's storm, a natural avalanche cycle occurred with notable very large avalanches (size 3) failing in wind-loaded terrain.

As northeasterly outflow winds increased on Monday night, operators in the north of the region reported several small (size 1) natural wind slabs from steep terrain.

Looking forward to Wednesday, we expect easterly winds to continue to form fresh wind slabs on south and west-facing slopes. These wind slabs will be in more atypical areas that are usually windward, which may take riders by surprise.

Snowpack and avalanche observation data are currently very limited in this region. If you head out in the backcountry, please consider posting your observations to the MIN. (Mountain Information Network)

Snowpack Summary

Last week's storm delivered 70-150 cm of new snow accompanied by very strong southwest ridgetop winds.

Over the past 2 days, strong easterly outflow winds and cold temperatures have started to stiffen the upper snowpack and strip wind ward, easterly aspects. In areas where the storm snow remains loose and powdery, these winds may redistribute it into fresh windslabs.

This storm snow overlies a hard old surface created during the mid-November cool period. This layer consists of a crust below ~1200m and a layer of surface hoar, which has been found primarily in isolated, protected terrain. This layer has not shown any alarming reactivity at this time.

The depth of the snowpack at treeline varies widely from 100-200 cm and tapers rapidly below treeline.

Many early-season hazards such as rocks, stumps, and open creeks exist below treeline.

Weather Summary

Tuesday night

A mix of sun and cloud. Easterly outflow winds increasing to 50-90 km/h. Temperatures dropping to -25 C at treeline.

Wednesday

Mainly sunny. Easterly winds 40-80km/h. High temperature at treeline -22 C.

Thursday

Partially cloudy. Light variable winds. Temperatures rising, high temperature at treeline -13 C.

Friday

A mix of sun and cloud. Easterly winds 40-60km/h. High temperature -12 C at treeline.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
Recent wind has varied in direction so watch for wind slabs on all aspects.
Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
Use ridges or ribs to avoid areas of wind loaded snow.

Problems

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.