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Avalanche Forecast

Archived

Nov 25th, 2020–Nov 26th, 2020

Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural and human triggered avalanches likely.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.

Regions

South Coast.

Welcome to the first forecast of the season! The bond of the recent snowfall is what to investigate, particularly where substantial amounts of snow may have accumulated at higher elevations.

Confidence

Moderate - Uncertainty is due to the limited number of field observations.

Weather Forecast

WEDNESDAY NIGHT: Partly cloudy, light northwest wind, treeline temperature -2 C, freezing level 1000 m.

THURSDAY: Cloudy with late afternoon snowfall, accumulation 5 cm, moderate west wind, treeline temperature -1 C, freezing level 1100 m.

FRIDAY: Cloudy with snowfall, accumulation 20 cm, strong southwest wind, treeline temperature 0 C, freezing level 1400 m.

SATURDAY: Early-morning snowfall then clearing, accumulation 30 to 40 cm, moderate west wind, treeline temperature -3 C, freezing level 1000 m.

Avalanche Summary

Small slabs about 20 cm thick were triggered by skiers on the North Shore Mountains on Monday. We have not received any information since Tuesday's storm, but we suspect that similar avalanches could be triggered within Tuesday's storm snow, particularly at higher elevations.

Our eyes and ears in the mountains are limited at this time of year and may continue this winter due to fewer professional observations. If you see anything while out in the field, please consider sharing it with us and fellow recreationists via the Mountain Information Network (MIN). Even just a photo of where you went is helpful. A big thank you to those that have already shared their observations thus far.

Snowpack Summary

The snowpack depth rapidly changes with elevation. The snowline has been reported to be around 900 m. The snowpack rapidly jumps to around 100 cm deep above 1000 m and between 150 to 200 cm near the mountain tops.

Tuesday's storm dropped a mix of snow and rain at most elevations, with it only falling as snow above about 1500 m. Around 30 cm may have accumulated above 1500 m whereas 10 to 15 cm of moist snow likely accumulated below. Deeper deposits should be expected in lee terrain features at higher elevations.

Numerous melt-freeze crusts and ice layers exists in the snowpack and reports indicate that the surrounding snow is well-bonded to them.

Terrain and Travel

  • Investigate the bond of the recent snow before committing to your line.
  • Be alert to conditions that change with elevation.
  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Be cautious of buried obstacles especially below treeline.

Problems

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.