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Avalanche Forecast

Archived

Dec 12th, 2023–Dec 13th, 2023

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

Regions

Sea To Sky, Brandywine, Garibaldi, Homathko, Spearhead, Tantalus, Sky Pilot.

Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.

Confidence

High

Avalanche Summary

On Monday, evidence of the natural avalanche cycle from last weekend continued to be reported with size 1 to 1.5 wind slab and storm slab avalanches being reported.

Explosives control in the region produced size 1.5 storm slab avalanches in lee features above 1900 m.

Thank you to everyone who has been sharing observations on the Mountain Information Network. All the information and photos are very appreciated by forecasters!

Snowpack Summary

A thin melt freeze crust covers 15-20 cm of recent snow. Above 1900 m recent snow overlies a layer of preserved surface hoar above a crust. This weak layer was very reactive during the last storm cycle.

Below 1900m snow surface is moist or in various stages of refreezing. 50 cm down is a thick widespread supportive crust.

Overall, the snow depth remains relatively shallow, with numerous hazards present at or just below the snow surface across all elevations.

Weather Summary

Tuesday Night

Partly cloudy with no precipitation, southwest alpine winds 30 to 50 km/h, treeline temperature 0 °C, freezing levels remain between 2000 and 2500 m overnight.

Wednesday

Cloudy with isolated flurries, 1 to 5 mm accumulation, southwest alpine wind 60 to 80 km/h, treeline temperature -2 °C, freezing levels drop to 1200 m through the day.

Flurries continue overnight bringing another 10 to 20 mm of accumulation.

Thursday

Cloudy with scattered flurries, 2 to 6 mm accumulation, northwest alpine wind 10 to 25 km/h, treeline temperature -3 °C, freezing level 1000 m.

Friday

Mainly cloudy with scattered flurries, 3 to 10 mm accumulation, southwest alpine wind 30 to 50 km/h, treeline temperature -3 °C, freezing level 2000 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Be careful with wind slabs, especially in steep, unsupported and/or convex terrain features.
  • Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
  • Early season avalanches at any elevation have the potential to be particularly dangerous due to obstacles that are exposed or just below the surface.

Problems

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.