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Avalanche Forecast

Archived

Nov 27th, 2023–Nov 28th, 2023

Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely.
Below Treeline
Natural avalanches unlikely.

Regions

Northwest Coastal, Stewart, Ningunsaw, Ningunsaw.

A weak layer near the bottom of the snowpack means there is the potential for large natural and human triggered avalanches.

Confidence

Low

Avalanche Summary

Reports of avalanche activity have tapered since the storm but 1 large (size 2.5) natural avalanche in the alpine on a northwest facing slope was reported on Sunday.

Observations are very limited at this time of year. If you do head out, do so with a cautious and investigative mindset, and consider submitting a MIN report.

Snowpack Summary

Warm temperatures and rain at lower elevations have made for a moist and heavy snowpack, at higher elevations 5-15 cm of new snow is now burying an old surface crust.

Observations are limited, but above 1500 m a problematic crust/facet combination exists near the base of the snowpack in the Bear Pass and Ningunsaw's area (likely elsewhere too). With total snowpack depths around 150 cm at 1000 m, this layer is a concern for human triggering, particularly in shallow or variable depth snowpack areas in the alpine.

Weather Summary

Monday night

Cloudy with snow, 5 to 10 cm accumulation, southwest alpine wind 40 to 70 km/h, treeline temperature -3 °C.

Tuesday

Mix of sun and clouds with light flurries, northwest alpine wind 30 to 40 km/h, treeline temperature -8 °C.

Wednesday

Mostly cloudy with light flurries, southeast alpine wind 30 to 50 km/h, treeline temperature -12 °C.

Thursday

Mostly cloudy with light flurries, southeast alpine wind 30 to 40 km/h, treeline temperature -9 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Make observations and assess conditions continually as you travel.
  • Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
  • Dial back your terrain choices if you are seeing more than 25cm of new snow.

Problems

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.

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.