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Avalanche Forecast

Archived

Dec 15th, 2025–Dec 16th, 2025

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

Regions

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

The next wave of the storm puts us back in snowpack building mode. Keep avoiding avalanche terrain in the alpine and keep your guard up everywhere else.

Confidence

Moderate

Avalanche Summary

A natural wet slab avalanche cycle to size 3 has been observed in the Whistler area after around 70 mm of rain below 2000 m and heavy alpine snow in the past 24 hours. Monday morning, new size 1.5 wet loose releases were observed and explosives produced a size 2 wet slab. The largest releases likely involved the November crust as a failure plane.

Looking forward, heavy snowfall and warm temperatures are expected to perpetuate more activity of a similar nature.

Snowpack Summary

Roughly 30 - 40 cm of new snow should accumulate above about 1200 m by end of day Tuesday, blanketing a rain-soaked snowpack to 2000 m and adding to somewhat uncertain dry 24-hour snow accumulations in higher alpine locations. A reactive new storm slab problem should be the result.

A crust with facets, formed in mid-November, was buried 60-120 cm deep, depending on the aspect, before the storm. Monday's rain will continue to promote destructive avalanches at this layer. Forecast heavy snowfall prevents us from gaining much confidence in it, even as temperatures cool.

Weather Summary

Monday Night
Cloudy with easing precipitation bringing 15 to 20 cm of new snow. 40 km/h southwest ridgetop wind. Treeline temperature -5 °C. Freezing level bottoms out at 1100 m.

Tuesday
Cloudy with increasing snowfall bringing 15 to 25 cm of new snow. 30 - 40 km/h south ridgetop wind, increasing. Treeline temperature around -2 °C. Freezing level 1200 - 1400 m.

Wednesday
Mostly cloudy with scattered flurries adding up to 5 cm after 30 - 40 cm overnight. 20 - 40 km/h southwest ridgetop wind. Treeline temperature -5 °C. Freezing level 1100 m.

Thursday
Mostly cloudy with increasing flurries bringing 10 to 25 cm of new snow, including overnight amounts. 40 km/h south ridgetop wind. Treeline temperature -2 °C. Freezing level rising from 1000 to 1400 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Avoid avalanche terrain during periods of heavy loading from new snow, wind, or rain.
  • Storm slab size and sensitivity to triggering will likely increase through the day.
  • Only the most simple non-avalanche terrain with no overhead hazard is appropriate at this time.

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.

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.