Avalanche Forecast

Archived

Dec 17th, 2024–Dec 18th, 2024

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Regions

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

If you find a thick, hard crust capping the snowpack, then hazard is low. Use extra caution if you find either wet snow, or dry wind-blown snow at upper elevations.

Confidence

Low

Avalanche Summary

On Sunday, shooting cracks and small slabs were triggered by riders near Mt.Arrowsmith.

On Saturday, several storm slab avalanches sized 1 to 1.5, were rider-triggered near Mt.Washington.

We expect a widespread wet avalanche cycle to occur Tuesday night during the storm, but that danger will drop rapidly, due to freezing levels returning to 1200 m by morning.

Snowpack Summary

30 to 75 mm of rain is expected to saturate the snowpack right to mountaintop overnight Tuesday. By Wednesday morning the freezing level should drop back to 1200 m and freeze the wet snow into a crust. There is a chance some late precipitation could fall as snow over the crust as the storm moves out. This would improve the riding quality, but also create potential wind slabs on north and west aspects at upper elevations. This storm is forecast to favour the southern and western parts of the Island with higher precipitation amounts.

The mid and lower snowpack is well-settled with no layers of concern.

Total snow depths at treeline vary; from 240 cm near Mt. Washington, to 140 cm near Mt Cain.

Weather Summary

Tuesday Night

Cloudy, with heavy to very heavy rain (30 to 75 mm). 80 to 100 km/h southwest ridgetop wind. Treeline temperature 6 °C. Freezing level rising to 2500 m.

Wednesday

A mix of sun and cloud. 55 to 75 km/h west ridgetop wind. Treeline temperature 2 °C. Freezing level dropping to 1200 m.

Thursday

Cloudy with with moderate to heavy rain. 80 to 95 km/h south ridgetop wind. Treeline temperature 4 °C. Freezing level rising to 2300 m.

Friday

Mostly sunny. 70 km/h south ridgetop wind. Treeline temperature 8 °C. Freezing level rising to 3200 m.

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.
Avalanche activity is unlikely when a thick melt-freeze crust is present on the snow surface.
Loose avalanches may start small, but they can grow and push you into dangerous terrain.

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.

Loose Wet

Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.