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Avalanche Forecast

Archived

Dec 16th, 2023–Dec 17th, 2023

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

Regions

North Rockies, McBride, Sugarbowl, Kakwa, McGregor, Renshaw, Robson.

Be patient, choose mellow terrain, and give the snowpack time to adjust to the new load.

Storm slabs and buried weak layers may be primed for human triggering.

Confidence

Moderate

Avalanche Summary

No new avalanches were reported on Saturday before 4 pm. We expect that human triggered avalanches will remain likely on Sunday.

If you go out in the backcountry, please consider sharing your observations on the Mountain Information Network (MIN).

Snowpack Summary

Friday night, 20-30 cm of storm snow arrived with strong southwest winds forming reactive storm slabs. This recent snow sits on old, hard surfaces, like windslabs or a frozen crust, which are good sliding surfaces for avalanches.

A concerning layer of surface hoar can be found 50-90 cm below the snow surface.

A crust with sugary facets beneath it can be found just above the ground. Average snowpack depths at treeline range from 65 to 100 cm.

Weather Summary

Saturday Night

Partly cloudy. Trace of snow expected. Light to moderate southwest ridgetop wind. Treeline low around -6°C. Freezing level at valley bottom.

Sunday

Partly cloudy. No new snow expected. Moderate southwest ridgetop wind. Treeline high around -2°C with possible temperature inversion.

Monday

Cloudy. 5-10 cm of snow expected. Light southeast ridgetop wind. Treeline temperature around -2°C with possible temperature inversion.

Tuesday

Cloudy. 2-5 cm of snow expected. Light to moderate southwest ridgetop wind. Treeline temperature around -2°C with possible temperature inversion.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Look for signs of instability: whumphing, hollow sounds, shooting cracks, and recent avalanches.
  • Give the new snow several days to settle and stabilize before pushing into bigger terrain.
  • Storm slabs in motion may step down to deeper layers resulting in large avalanches.

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.