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 20th, 2024–Dec 21st, 2024

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

Regions

Kootenay Boundary, Bonnington, Grohman, Kootenay Pass, Norns, Rossland, Ymir, Crawford, Moyie, St. Mary, West Purcell, Badshot-Battle, Goat, Kokanee, Retallack, Valhalla, Whatshan.

Don't let good riding lure you into complacency, large and surprising avalanches have failed on buried weak layers in the past few days.

Tune in to Nelson's State of the Snowpack!

Confidence

Moderate

Avalanche Summary

A widespread natural avalanche cycle took place during the storm on Wednesday. Observations have been limited following the storm, but there have been several persistent slab avalanches reported throughout the region since (size 2).

Snowpack Summary

As much as 60 cm of recent snow has been redistributed by southwest winds into deeper deposits in lee terrain features at higher elevations.

A weak layer of surface hoar in sheltered, shaded terrain and a sun crust on south-facing terrain is now buried 40 to 90 cm. This layer has been most active in the Goat Range.

The lower snowpack is strong and bonded. Treeline snow depths range from 100 to 180 cm.

Listen in to Friday night's State of the Snowpack for more details on the snowpack and avalanche danger.

Weather Summary

Friday Night

Cloudy with up to 5 cm of new snow. 15 to 40 km/h southwest ridgetop wind. Treeline temperature -1 °C.

Saturday

A mix of sun and cloud with up to 2 cm of new snow. 15 to 40 km/h southwest ridgetop wind. Treeline temperature -1 °C.

Sunday

A mix of sun and cloud with isolated flurries. 20 to 50 km/h southwest ridgetop wind. Treeline temperature -3 °C.

Monday

Cloudy with up to 5 cm of new snow. 15 to 40 km/h southwest ridgetop wind. Treeline temperature -3 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Stay off recently wind loaded slopes until they have had a chance to stabilize.
  • Uncertainty is best managed through conservative terrain choices.
  • Approach steep and open slopes at and below treeline cautiously, as buried surface hoar may exist.
  • Be aware of the potential for large avalanches due to a buried crust.

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.

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.