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Avalanche Forecast

Archived

Dec 20th, 2022–Dec 21st, 2022

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

Regions

North Columbia, South Columbia, Blue River, Premier, Clemina, Esplanade, Jordan, North Monashee, North Selkirk, West Purcell, Badshot-Battle, Central Selkirk, Goat, Gold, Whatshan.

Avalanche activity on the persistent weak layers has decreased. However, it is important to stay vigilant. Maintain good travel habits and check out our forecaster blog on managing a persistent slab.

Come prepared with lots of warm layers, hot drinks and a headlamp when venturing out. Cold temperatures and short days can turn even small incidents like broken equipment into a very bad time.

Confidence

Moderate

Avalanche Summary

On Monday, two natural size 2 wind slab avalanches were observed, and several smaller wind slabs released in steep terrain. A size 2 slab avalanche was triggered remotely by riders, and two small size 1 wind slabs were triggered by skiers. Explosive control resulted in a small slab avalanche.

On Sunday, skiers triggered several small avalanches of size 1 below treeline about 40 cm deep. A small natural avalanche released on a northern aspect around 2000 m and there were several reports of whumpfing and shooting cracks.

On Saturday, skiers triggered a size 1 wind slab avalanche on a southeast aspect at 2300 m.

Snowpack Summary

Snowpack depths at treeline range from 100-150 cm. In the alpine, snowpack depths are highly variable from extensive wind-affect in many locations.

Surface: 5-15 cm of recent snow overlies 5-8 mm surface hoar in sheltered areas. On steep solar slopes, new snow overlies a sun crust. Moderate westerly winds have built thin wind slabs in alpine lees.

Upper-pack: Cold temperatures are faceting the upper snowpack. 40-50 cm settling snow overlies a weak layer of 5 mm surface hoar in sheltered and shaded terrain and a sun crust on sunny south-facing slopes.

Mid-pack: Buried 60-90 cm deep, is a persistent weak layer of surface hoar, crust, and faceted crystals. This layer has been most reactive at treeline between 1700-2200 m, but it was also observed as low as 1450 m and on all aspects.

Lower-pack: Below the mid-November layer is a generally weak, faceted snowpack.

Weather Summary

Tuesday Night

Decreasing cloud coverage, trace of snow, 20 km/h northerly wind, temperature low at -32 °C.

Wednesday

Mix of sun and some clouds, trace of new snow, 20 km/h northeast wind, temperature high around -26 °C.

Thursday

Sunny, 10 km/h easterly wind, temperature high at -27 °C.

Friday

Cloudy, 5-10 cm new snow, 40 km/h southerly wind, temperature high at -20 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Be mindful that deep instabilities are still present and have produced recent large avalanches.
  • Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.
  • Avoid making assumptions about this layer based on the presence of aggressive tracks on adjacent slopes

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.