Avalanche Forecast

Archived

Dec 14th, 2025–Dec 15th, 2025

Alpine

Natural and human triggered avalanches likely.

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.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Regions

Coquihalla, Harrison-Fraser, Manning, Skagit.

Stormy weather continues, bringing extreme winds and up to 90 mm of precipitation as rain or snow by Monday afternoon.

Travel in avalanche terrain is not recommended.

Confidence

Moderate

Avalanche Summary

Last Wednesday, a very large size 3 avalanche stepped down to a persistent weak layer near Allison Pass. Several wet loose avalanches also occurred, see photo captions for more details.

Looking forward, as another atmospheric river brings significant precipitation, we can expect to see more large avalanches occurring.

Snowpack Summary

50 to 90 mm of precipitation, combined with strong to extreme southerly winds, is forecast to fall by 4 pm Monday. We expect to see widespread reactive storm slabs building as a result.

The snow/rain line elevation is uncertain and expected to fluctuate during the storm. It's possible we could see rain up to 2100 m. There is potential for wet loose avalanches where the snow surface is wet.

A crust with facets, formed in mid-November, was buried 50 to 100 cm before the storm. Storm slabs have the potential to step down to this layer, causing very large avalanches.

Total snowpack depths range from 80 to 140 cm deep at treeline, and diminish rapidly below 1500 m.

Weather Summary

Sunday Night
Cloudy. 10 to 30 mm of precipitation as rain or snow at treeline. 50 km/h southwest ridgetop wind. Treeline temperature 2 °C. Freezing level 2000 m to 2400 m.

Monday
Cloudy. 40 to 60 mm of precipitation as rain or snow at treeline. 70 km/h southwest ridgetop wind. Treeline temperature 3 °C. Freezing level 1900 m to 2500 m.

Tuesday
Mostly cloudy. 20 to 30 cm of snow. 50 km/h southwest ridgetop wind. Treeline temperature -3 °C. Freezing level 1200 m to 1400 m.

Wednesday
Mostly cloudy. 30 to 50 cm of snow. 50 km/h west ridgetop wind. Treeline temperature -6 °C. Freezing level 1000 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.
Avoid exposure to overhead avalanche terrain; avalanches may run surprisingly far.
Storm slab size and sensitivity to triggering will likely increase through the day.

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.