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Avalanche Forecast

Archived

Dec 28th, 2024–Dec 29th, 2024

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

Regions

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

Information on lingering storm instabilities is still in short supply, so bring an assessment mindset with you on Sunday. Wind slab sitting on near-surface crust is the most likely problem.

Confidence

Moderate

Avalanche Summary

No new avalanches were reported on Friday.

Explosives control in the Mount Washington area produced several more size 1.5 - 2 wind slabs in west-facing terrain Thursday.

Numerous size 1 - 1.5 slabs were seen throughout north-facing terrain in the same area Wednesday as well as a size 2 storm slab triggered accidentally by a skier walking along a ridgeline. An island-wide large avalanche cycle took place during the height of the Christmas storm.

Snowpack Summary

Warm temperatures or rain should create a surface crust below about 1400 m and otherwise aid in the rapid settlement of 50 - 80 cm of new snow since Dec 24; 10 - 30 cm of this came Friday night through Saturday. In exposed areas, strong winds have led to a wide-ranging 0 - 200 cm sitting on the pre-storm crust!

Drier snow at higher elevations has likely remained more available for wind transport and should be investigated carefully for the presence and reactivity of wind slabs.

Below the new snow, the snowpack is thoroughly settled and bonded.

Snowpack depths at treeline are now about 130 -180 cm on the north and south island, closer to 250 to 300 cm on the central island.

Weather Summary

Saturday night

Diminishing cloud and easing flurries with minimal accumulations. 20 to 50 km/h southwest ridgetop wind shifting southeast and easing. Freezing level 1000 m.

Sunday

Mainly cloudy with scattered flurries bringing up to 5 cm of new snow in the afternoon/evening. 20 to 40 km/h southeast ridgetop wind shifting southwest and increasing. Freezing level falling from 1100 m to 800 m in the afternoon.

Monday

Mainly cloudy with isolated flurries after less than 5 cm accumulation overnight. 10 to 30 km/h southwest ridgetop wind. Freezing level 800 m to 1000 m.

Tuesday

Cloudy with flurries bringing up to 10 cm of new snow. 40 to 60 km/h southeast ridgetop wind, increasing. Freezing level 700 m to 900 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Be alert to conditions that change with elevation, aspect, and exposure to wind.
  • Watch for newly formed and reactive wind slabs as you transition into wind-affected terrain.
  • Avalanche activity is unlikely when a thick melt-freeze crust is present on the snow 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.