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Avalanche Forecast

Archived

Jan 5th, 2023–Jan 6th, 2023

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

Regions

Kootenay Boundary, Bonnington, Kootenay Pass, Norns, Rossland, Ymir, Moyie, St. Mary.

With snow available for transport and wind in the forecast, wind slabs will be developing throughout the day. Monitor the wind direction and anticipate slopes where newly formed wind slabs may exist.

Confidence

Moderate

Avalanche Summary

After a dynamic period of large avalanches occurring on deep persistent weak layers, reported avalanche activity has tapered.

Going forward, snow available for transport may build touchy wind slabs over various surfaces.

Snowpack Summary

Forecasted flurries overnight will further bury various surfaces of crust on steep south-facing slopes, surface hoar that developed over the past few days, and 30 to 40 cm of previous snow. A hard melt-freeze crust can be found up to 2000 m. Where it is robust enough to do so, this crust appears to be effectively bridging deeper instabilities, making them more difficult to trigger.

The two persistent weak layers are a 60 to 80 cm deep surface hoar/crust layer that was buried in mid-December and an 80 to 150 cm deep surface hoar/facet layer buried in mid-November.

Weather Summary

Thursday night

Cloudy with 5 cm of new snow, 30 km/h south winds, treeline temperature around -4 °C.

Friday

Cloudy with 5 to 10 cm new snow, 20 to 30 km/h southwest wind, treeline temperature around -5 °C, freezing level 800 m.

Saturday

Cloudy, up to 10 cm of new snow, southeast wind easing to 15 to 20 km/h, treeline temperature -5 °C, freezing level 800 m.

Sunday

Cloudy, up to 5cm of new snow, 20 to 30 km/h south winds, treeline temperatures -5 °C

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Pay attention to the wind, once it starts to blow fresh sensitive wind slabs are likely to form.
  • Be mindful that deep instabilities are still present and have produced recent large avalanches.

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.