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Avalanche Forecast

Archived

Dec 20th, 2025–Dec 21st, 2025

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

Regions

South Coast Inland, Birkenhead, Duffey, South Chilcotin, Stein, Taseko.

Strong winds and fresh flurries will build reactive deposits around ridges and lee features.

If more than 20 cm of new snow accumulates, expect a more widespread slab avalanche problem.

Confidence

Moderate

  • Uncertainty is due to the speed, direction, or duration of the wind and its effect on the snowpack.

Avalanche Summary

No new avalanches were reported in the region since Monday.

On Friday, in the adjacent Sea to Sky forecast region, explosives triggered size 1-2 storm slab avalanches, failing either within the storm snow or on a crust. The few size 2 avalanches were triggered in steep, wind-loaded lee features.

Last Monday, several large (size 2.5 to 3) natural avalanches occurred along the Duffey corridor. These all failed on the mid-November crust and facet layer.

Snowpack Summary

Strong southerly winds are impacting flurries and modifying snow surfaces.

Over the last week, 30 to 50 cm of storm snow accumulated, accompanied by strong alpine winds. This covers a melt-freeze crust that becomes increasingly supportive above 1700 m.

A deeper crust with associated facets, formed in mid-November, exists 50 to 150 cm below the surface and has been responsible for recent large avalanche activity.

Weather Summary

Saturday night
Mostly cloudy. Trace to 5 cm of snow. 30 km/h southwest ridgetop wind. Treeline temperature -6 °C.

Sunday
Mostly cloudy. 15 to 20 cm of snow. 20 km/h south ridgetop wind. Treeline temperature -4 °C.

Monday
Cloudy. 15 cm of snow. 20 km/h south ridgetop wind. Treeline temperature -6 °C.

Tuesday
Mostly cloudy. 10 cm of snow. 30 km/h south ridgetop wind. Treeline temperature -6 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Be especially cautious as you transition into wind-affected terrain.
  • Dial back your terrain choices if you are seeing more than 20 cm of new snow.
  • Avoid shallow, rocky areas where the snowpack transitions from thick to thin.

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.

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.