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Avalanche Forecast

Archived

Dec 17th, 2024–Dec 18th, 2024

Alpine
Natural and human triggered avalanches likely.
Treeline
Natural and human triggered avalanches likely.
Below Treeline
Natural avalanches possible, human triggered probable.
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 possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches possible, human triggered probable.

Regions

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

Avalanche danger will be HIGH in areas with more than 30 cm of new snow.

Confidence

Moderate

Avalanche Summary

Natural avalanches are expected on Wednesday in areas with more than 30 cm of snow and on wind-loaded slopes.

On Monday, a few small (size 1) soft slab avalanches were reported, some failing on a 10 to 25 cm deep surface hoar layer.

Snowpack Summary

10 to 20 cm of snow overnight and another 10 to 25 cm during the day will cause short-lived instabilities within the storm snow. Expect deep wind drifts at higher elevations.

The upper snowpack has a mix of crusts and surface hoar layers 20 to 40 cm deep, but assessing the distribution of weak layers is difficult because in some areas a freezing rain crust destroyed or buried the surface hoar.

The lower snowpack is strong and bonded. Treeline snow depths range from 100 to 150 cm.

Weather Summary

Tuesday Night

Cloudy with 10 to 20 cm of snow. 40 to 60 km/h south ridgetop wind. Treeline temperature -5 °C.

Wednesday

Cloudy with 10 to 25 cm of snow. 50 to 70 km/h southwest ridgetop wind. Treeline temperature -3 °C. Freezing level 1500 m in the afternoon.

Thursday

Sunny with cloud increasing in the afternoon. 20 km/h southwest ridgetop wind. Treeline temperature -5 °C.

Friday

Up to 5 cm of snow overnight then clearing skies throughout the day. 20 km/h southwest ridgetop wind. Treeline temperature +2 °C. Freezing level climbing to 3000 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Only the most simple non-avalanche terrain with no overhead hazard is appropriate at this time.
  • Storm slab size and sensitivity to triggering will likely increase through the day.

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.