Avalanche Forecast

Archived

Jan 10th, 2025–Jan 11th, 2025

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.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Regions

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

New snow and wind have created dangerous avalanche conditions.

Conservative route selection and avoiding overhead hazard is strongly recommended

Confidence

Moderate

Avalanche Summary

Thursday, numerous large and very large (size 2 to 3) natural and explosive-triggered storm slabs were reported.

Wednesday, a couple skier-triggered slabs size 1.5-2 were reported on west aspects at alpine/treeline elevations. The failure plane was identified as a layer of surface hoar layer beneath the recent storm snow. Natural storm slabs (size 2 to 3) were also observed. Notably, only a few cases failed on the persistent weak layer.

Snowpack Summary

Since the start of the week, 40 to 80 cm has accumulated in the alpine. Some of this new snow fell as rain Thursday night, with the rain/snow line around 1200 m. A crust or wet snow may exist below that elevation.

The storm snow isn't expected to bond well as it sits on a layer of surface hoar, facets, or a thin crust.

Strong winds have been redistributing the new snow at upper elevations, 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

Friday Night

Cloudy with 0 to 5 cm of snow / light rain below 1000 m. 50 km/h northwest ridgetop wind. Treeline temperature -1 °C.

Saturday

Cloudy with 0 to 4 cm of snow. 30 to 50 km/h west ridgetop wind. Treeline temperature -3 °C. Freezing level valley bottom.

Sunday

A mix of sun and cloud. 20 to 40 km/h west ridgetop wind. Treeline temperature -4 °C. Freezing level valley bottom.

Monday

Cloudy with 2 to 6 cm of snow. 50 to 70 km/h southwest ridgetop wind. Treeline temperature -2 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Use conservative route selection. Choose simple, low angle terrain with no overhead hazard.
Use increased caution at all elevations. Storm snow is forming touchy slabs.
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.

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.