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Avalanche Forecast

Archived

Dec 16th, 2025–Dec 17th, 2025

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

Regions

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

A juicy storm will form fresh problems Tuesday night. Start small on Wednesday as you gather info. Call danger HIGH if you encounter more than 30 cm of new snow or signs of instability.

Confidence

Moderate

  • Forecast precipitation (either snow or rain) amounts are uncertain.
  • Uncertainty is due to rapidly fluctuating freezing levels.

Avalanche Summary

A wet slab avalanche cycle to size 3 was observed in the Whistler area after around 90 mm of rain below 2000 m accompanied by heavy alpine snow. Monday morning, new size 1.5 wet loose releases were observed and explosives produced a size 2.5 wet slab. There's a good chance the largest releases involved the November crust as a failure plane.

Looking forward, more snowfall and mild temperatures are expected to perpetuate active conditions, with a shift toward dry slab activity.

Snowpack Summary

20 to 30 cm of new snow should accumulate above 1500 m by Wednesday morning, bringing 24-hour totals to a possible 50 cm, increasing with elevation. This will overlie a rain-soaked snowpack to 2000 m and add to somewhat uncertain recent dry snow accumulations in higher alpine locations.

A crust with facets, formed in mid-November, was buried 50-120 cm deep, depending on the aspect, before the storm. Wednesday's cooling trend after all the rain bodes well for stabilizing this layer, but limited observations prevent us from gaining total confidence in it, particularly in alpine locations that may have escaped the bulk of the rain.

Weather Summary

Tuesday Night
Cloudy with continuing snowfall bringing 20 to 30 cm of new snow, rain as high as 1500 m. 40 km/h southwest ridgetop wind. Treeline temperature reaching 0 °C with a brief 1700 m freezing level.

Wednesday
Mostly cloudy with isolated flurries and 2 to 3 cm of new snow. 30 km/h southwest ridgetop wind. Treeline temperature -5 °C. Freezing level 1000 m.

Thursday
Cloudy with continuing flurries bringing 10 to 25 cm of new snow, including overight amounts. 20 to 30 km/h south ridgetop wind. Treeline temperature -3 °C. Freezing level 1200 m.

Friday
A mix of sun and cloud with scattered flurries and a few cm of new snow. 10 km/h west ridgetop wind. Treeline temperature -7 °C. Freezing level 600 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Continue to make conservative terrain choices while the storm snow settles and stabilizes.
  • Make observations and continually assess conditions as you travel.
  • Avoid freshly wind-loaded terrain features.

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.