Avalanche Forecast

Archived

Dec 11th, 2025–Dec 12th, 2025

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 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.

Regions

Sea To Sky, Brandywine, Garibaldi, Homathko, Powell River, Spearhead, Tantalus.

The greatest concern is for alpine north through east-facing, leeward and crossloaded slopes, where both storm slabs and persistent slabs have been most reactive.

Confidence

Moderate

Avalanche Summary

Numerous size 1 to 2.5 explosive and human-triggered storm slabs were reported in the Whistler/ Blackcomb area throughout the recent storm cycle. A few of these slabs stepped down to the Mid-November crust up to 1 m deep, setting off larger than expected avalanches. Most of these slabs released in leeward north through east facing and crossloaded features.

We expect storm slabs and persistent slabs to remain possible to trigger on Friday

Snowpack Summary

A stormy week has brought up to 80 mm into the region, forming widespread storm slabs that may still be settling and bonding.

10 to 20 cm of snow is forecast to fall overnight and through Friday above 1800 m. The new snow may be accompanied by moderate southwesterly winds forming fresh slabs, especially in leeward terrain.

In the alpine, a hard mid-November crust now lies 60–120 cm deep, depending on aspect, with weak facets both above and below it. Recent storm slabs have in some cases, stepped down to this persistent weak layer. Wind-loaded, north-facing terrain appears to be the most concerning.

A meltfreeze crust caps the surface below around 1800 m. The snowpack rapidly diminishes below 1100 m.

Weather Summary

Thursday Night
Cloudy. 2 to 5 cm of snow. 20 km/h outhwest ridgetop wind. Treeline temperature -3 °C. Freezing level 1000 m.

Friday
Cloudy. 5 to 10 mm of precipitation as snow or rain at treeline. 30 km/h southwest ridgetop wind. Treeline temperature 1 °C. Freezing level rising to 1800 m.

Saturday
Mostly cloudy. 10 to 25 mm of precipitation as snow or rain at treeline. 30 km/h southwest ridgetop wind. Treeline temperature 0 °C. Freezing level 1800 m.

Sunday
Mostly cloudy. 45 to 55 mm of precipitation as snow or rain at treeline. 40 km/h southwest ridgetop wind. Treeline temperature 0 °C. Freezing level 1700 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Storm slabs in motion may step down to deeper layers resulting in large avalanches.
Avoid freshly wind-loaded terrain features.
Avalanche activity is unlikely when a thick melt-freeze crust is present on the snow surface.

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.

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.