Avalanche Forecast

Archived

Jan 11th, 2025–Jan 12th, 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 unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Alpine

Natural and human triggered avalanches likely.

Treeline

Natural and human triggered avalanches likely.

Below Treeline

Natural avalanches possible, human triggered probable.

Regions

Northwest Coastal, Northwest Inland, Boundary, Kitimat, Nass, Rupert, Seven Sisters, Shames, Stewart, Kispiox, Ningunsaw, Ningunsaw, Ningunsaw.

Continue to make conservative terrain choices while the storm snow settles and bonds to underlying layers

Careful route selection and avoiding overhead hazard is recommended

Confidence

Moderate

Avalanche Summary

Numerous large and very large storm slabs up to size 3, occurred across the region over the last few days of stormy weather. Notably, only a few cases failed on the persistent weak layer.

Skiers have also reported widespread whumpfing and shooting cracks.

Looking forward, we expect natural avalanche activity to taper off, but for human triggering to remain likely at upper elevations.

Snowpack Summary

40 to 80 cm of recent storm snow has accumulated in the alpine, and is now settling rapidly with the mild temperatures. Some of this new snow fell as rain, with the rain/snow line around 900 -1200 m. A crust or wet snow may exist below those elevations.

The storm snow may be slow to bond because it sits on surface hoar, facets, or a thin crust.

Strong winds from various directions have been redistributing the new snow, building deeper and more reactive deposits on lee slopes.

A persistent weak layer of surface hoar and facets overlying a crust is buried 90 to 140 cm deep in the southern parts of the region, and up to 240 cm deep in areas north of Stewart. Avalanches failing on this layer will be very large and destructive.

Weather Summary

Saturday Night

Cloudy with 0 to 3 cm of snow. 50 km/h west ridgetop wind. Treeline temperature -2 °C.

Sunday

Partly cloudy. 25 to 35 km/h west ridgetop wind. Treeline temperature -2 °C.

Monday

Cloudy with 5 to 15 cm of snow. 55 km/h southwest ridgetop wind. Treeline temperature -1 °C.

Tuesday

Cloudy with 20 to 40 cm of snow. 80 km/h southwest ridgetop wind. Treeline temperature 0 °C. Freezing level 1300 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Be aware of the potential for remote triggering and large avalanches due to buried surface hoar.
Be especially cautious as you transition into wind-affected terrain.
Keep in mind that human triggering may persist as natural avalanches taper off.
Be mindful that deep instabilities are still present and have produced recent large avalanches.

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.