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Avalanche Forecast

Archived

Dec 22nd, 2024–Dec 23rd, 2024

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.
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, Badshot-Battle, Goat, Kokanee, Retallack, Valhalla, Whatshan.

The variable distribution of buried weak layers makes assessing avalanche danger tricky. Use caution on steep open slopes at treeline and below, where these layers have been most active.

Confidence

Moderate

Avalanche Summary

Following a widespread avalanche cycle last Wednesday, several human-triggered avalanches have been reported on a buried surface hoar layer.

These avalanches, occurring on north-facing terrain, have been approximately 50 cm deep and range from size 1 to 2. Notably, two avalanches were remote-triggered, including one from 100 meters away by a group of skiers.

Remote-triggered avalanches are a strong sign of an unstable snowpack.

Snowpack Summary

Up to 10 cm of fresh snow has fallen on top of storm snow from earlier in the week. The upper snowpack continues to settle and bond with recent mild temperatures. Wind-affected snow is present at the surface in exposed terrain at higher elevations. At lower elevations, surface conditions range from crusty to moist, depending on the time of day and local temperatures.

Down 50 to 100 cm there are weak layers of facets, crusts, and in some places surface hoar. The distribution of these layers is highly variable throughout the region. Areas currently showing the greatest reactivity are the Goat Range, Bonningtons, and Rossland Range.

Treeline snow depths range from 100 to 180 cm.

Weather Summary

Sunday Night

Cloudy with 0 to 5 cm of snow. 20 to 30 km/h southwest ridgetop wind. Treeline temperature -5 °C.

Monday

Cloudy with 0 to 2 cm of snow. 20 to 30 km/h southwest ridgetop wind. Treeline temperature -5 °C.

Tuesday

Cloudy with up to 10 cm of snow. 20 to 40 km/h southwest ridgetop wind. Treeline temperature -3 °C.

Wednesday

Mix of sun and cloud. 20 to 40 km/h southwest ridgetop wind. Treeline temperature -5 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Approach steep and open slopes at and below treeline cautiously, as buried surface hoar may exist.
  • Surface hoar distribution is highly variable. Avoid generalizing your observations.
  • Be aware of the potential for large avalanches due to a buried crust.
  • Be careful as you transition into wind-affected terrain.

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.