Dashboard Regions Weather Stations Radar Alerts Glossary
Contact About
Log In

Register for an account and never miss a forecast again!

Register

Avalanche Forecast

Archived

Dec 29th, 2024–Dec 30th, 2024

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

Regions

Northwest Coastal, Boundary, Kitimat, Nass, Rupert, Seven Sisters, Shames, Stewart, Howson, Microwave-Sinclair, Ningunsaw, Ningunsaw, Ningunsaw.

A problematic weak layer has been producing large, hair-triggered avalanches north of Terrace. Careful snowpack evaluation and conservative decision-making are critical.

Confidence

Moderate

Avalanche Summary

Avalanche activity near Shames was limited to small (size 1-1.5) rider-triggered wind slabs on Saturday.

Between Terrace and Ningunsaw, large (size 2-3) natural and remotely-triggered persistent slab avalanches have been reported in recent days. These avalanches have been triggered from hundreds of meters away, failing on the early December weak layers and running on the early December crust. Check out these sobering MIN reports (1, 2) near Rosswood on Saturday.

Snowpack Summary

Extensively wind-affected surfaces exist in the alpine. Soft snow can be found in sheltered and lower elevation terrain. Below 1000 m, surface snow is moist and/or crusty.

50 to 100 cm of snow settles over a significant weak layer. The layer involves weak grains of surface hoar and facets sitting over a hard crust formed in early December. While this structure is an active problem north of Terrace, including in the Ashman and Douglas areas, observations have been less conclusive near Shames and to the south.

The remainder of the snowpack is well settled and bonded. Treeline snow depth range from 200-280 cm.

Weather Summary

Sunday night

Partly cloudy. <15 km/h variable ridgetop wind. Treeline temperature around -5 °C

Monday

A mix of sun and cloud. 10 to 15 km/h variable ridgetop wind. Treeline high temperature -5 °C.

Tuesday

Mainly cloudy. Isolated flurries with minimal accumulations. 30 to 40 km east or southeast ridgetop wind, increasing. Treeline high temperature -7 °C.

Wednesday

Mainly cloudy. Isolated flurries with minimal accumulations. 20 to 40 km east or southeast ridgetop wind. Treeline high temperature -10 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Be aware of the potential for large avalanches due to buried weak layers.
  • Remote triggering is a concern; avoid terrain where triggering overhead slopes is possible.
  • If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
  • In times of uncertainty, conservative terrain choices are our best defense.

Problems

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.

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind 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.