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Avalanche Forecast

Archived

Dec 12th, 2023–Dec 13th, 2023

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

Vancouver Island, East Island, North Island, South Island, West Island.

Wind slab size and reactivity will increase throughout Wednesday with the incoming wind and snow.

Confidence

Moderate

Avalanche Summary

No avalanches have been reported recently. We anticipate natural avalanche activity to increase through the day Wednesday with forecast strong winds and snow.

If you are out in the backcountry please consider filling out a MIN report.

Snowpack Summary

Snow arriving on Wednesday will bury a recently formed melt-freeze crust. Below the crust is 10-20 cm of storm snow from last weekend.

This snow sits on a combination of 1-3 cm crust and rimed surface hoar that constituted the pre-storm surface. Observations in the Mt Washington area on Sunday showed minimal bonding of the new snow to this layer.

Although the snow below this crust (and likely the snow above, as well) was previously moist from rain, it is for the most part dry and not particularly dense or consolidated.

In general, the snowpack is still quite shallow with many early-season hazards. Only specific terrain features with smooth ground cover and gullies are above the threshold for avalanches.

Weather Summary

Tuesday Night

Mostly cloudy with no precipitation, southwest alpine winds 70 to 100 km/h, freezing level dropping to 1600 m by the morning.

Wednesday

Cloudy with 5 to 15 cm of snow and rain at lower elevations, southwest alpine winds 70 to 90 km/h, treeline temperature 0 °C, freezing level to 1200 m by end of the day.

Thursday

Clearing skies with another 5 to 15 cm overnight ending by Thursday morning, southwest alpine winds 20 to 30 km/h, treeline temperature -1 °C, freezing level up to 1300 m by the end of the day.

Friday

Cloudy with 2 to 5 cm of snow at higher elevations and rain at lower elevations, southwest alpine winds 60 to 80 km/h, treeline temperature 3 °C, freezing level 1900 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Wind slabs are most reactive during their formation.
  • Closely monitor how the new snow is bonding to the crust.
  • Early season avalanches at any elevation have the potential to be particularly dangerous due to obstacles that are exposed or just below the surface.

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.