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Avalanche Forecast

Archived

Dec 26th, 2022–Dec 27th, 2022

Alpine
Natural and human triggered avalanches likely.
Treeline
Natural and human triggered avalanches likely.
Below Treeline
Natural and human triggered avalanches likely.
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.

Regions

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

Warm temperatures have increased the avalanche hazard.

Slabs are now primed to release and smaller avalanches may trigger buried weak layers producing large avalanches.

Confidence

Moderate

Avalanche Summary

Heavy snowfall over the weekend has increased avalanche activity substantially producing numerous small and large-scale avalanches.

The majority of these avalanches have occurred naturally from the storm snow. There have been a number of small and large avalanches that people have triggered accidentally. Again these have occurred from storm slabs but several large avalanches that were accidentally triggered by people have slid on buried weak layers.

Warming temperatures will promote slab properties in the snowpack. Slab reactivity is expected to increase in the storm snow as well as the multiple buried weak layers buried beneath.

Snowpack Summary

The top 50 to 75 cm of the snow pack was fairly unconsolidated before Monday's warming event. This is expected to change as warmth may promote slab properties of this top layer. At higher elevations, strong southwest winds will have redistributed much of this snow into fresh wind slabs. Slabs that are formed may not bond well to older surfaces.

Sitting just below this top layer lies up to three weak layers created earlier in December. Some of these may not exist in all areas of our region. The November weak layer, which will continue to be a concern in this warm-up, can be found anywhere between 75 and 125 cm down. The bottom of the snowpack is generally weak and faceted.

With snowpacks such as this, it is important to keep a heads up and know that very small avalanches can become very large very quickly. Check out our forecaster blog to learn about how to manage persistent slab problems.

Weather Summary

Monday Night

Mostly cloudy, up to 8 cm accumulation, 25 to 40 km/h south southwest wind, freezing levels between 1500 and 500 m.

Tuesday

Cloudy, 5 to 15 cm accumulation, 25 to 45 km/h southwest wind, treeline temperatures -2 °C.

Wednesday

Cloudy, 2 to 10 cm accumulation in some places, 10 to 25 km/h south wind, treeline temperatures -5 to -2 °C, and freezing levels up to 1100 m.

Thursday

A mix of sun and cloud, trace accumulation, 20 km/h southeast wind, treeline temperatures -8 to -5 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Good day to make conservative terrain choices.
  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Storm slabs in motion may step down to deeper layers resulting in large avalanches.
  • Watch for signs of slab formation throughout 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.

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.