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Avalanche Forecast

Archived

Dec 8th, 2023–Dec 9th, 2023

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

Regions

Kootenay Boundary, Bonnington, Grohman, Kootenay Pass, Norns, Rossland, Ymir, Crawford, Moyie, St. Mary, Kokanee, Retallack, Valhalla, Whatshan.

Riders could trigger storm slab avalanches, particularly where a buried weak layer lingers. The most likely terrain includes slopes that appear relatively smooth at higher elevations.

Confidence

Moderate

Avalanche Summary

Many storm slab and loose wet avalanches released during the intense rainy conditions earlier this week. Natural avalanche activity likely tapered on Friday.

Looking towards the weekend, riders could trigger storm slabs that formed the past few days. We're uncertain on whether avalanches could still release on the surface hoar layer described in the Snowpack Summary, so travelling cautiously until there is evidence it is bonding is a good strategy.

Snowpack Summary

Around 20 to 40 cm of snow rests on a hard melt-freeze crust or moist snow. This loads a buried weak layer of surface hoar found about 50 cm deep. This layer was likely destroyed in many steep slopes during intense rain loading, but it could still linger in isolated features where either the rain or an avalanche hasn't yet destroyed it.

The middle and lower snowpack are likely moist from all the recent rain and will slowly freeze into a hard crust.

Snowpack depths are generally between 60 and 110 cm at treeline, which quickly tapers as you lower with elevation.

Weather Summary

Friday Night

Clear skies with no precipitation, northwest alpine wind 20 km/h, treeline temperature -9 °C.

Saturday

Increasing cloud with 1 to 3 cm of afternoon snow, south alpine wind 20 to 30 km/h, treeline temperature -9 °C.

Sunday

Cloudy with 5 to 10 cm of snow, southwest alpine wind 20 km/h, treeline temperature -6 °C.

Monday

Mix of sun and cloud with 1 to 3 cm of early-morning snow, northeast alpine wind 10 km/h, treeline temperature -4 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Closely monitor how the new snow is bonding to the old surface.
  • Be aware of the potential for larger than expected storm slabs due to the presence of buried surface hoar.
  • Early season avalanches at any elevation have the potential to be particularly dangerous due to obstacles that are exposed or just below the surface.
  • Be cautious of buried obstacles especially below treeline.

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.