Avalanche Forecast

Archived

Dec 12th, 2023–Dec 13th, 2023

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 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

South Coast Inland, Birkenhead, Duffey, South Chilcotin, Stein, Taseko.

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

Carefully assess convex slopes and open rolls where a weak layer of surface hoar may be preserved.

Confidence

Moderate

Avalanche Summary

No new avalanches have been reported in the region on Tuesday.

This weekend size 1 to 2, natural storm slab avalanches were observed failing on the buried surface hoar layer down 40 - 50 cm at upper treeline.

If you're heading out in the backcountry, please consider sharing any observations on the Mountain Information Network

Snowpack Summary

20 to 30 cm of recent snow has been heavily wind affected in the alpine. Recent snow overlies a supportive crust at lower elevation which tapers out at 1950 m. 40-50 cm down a weak layer of surface hoar is preserved in sheltered areas at treeline. Below this is a series of crusts and basal facets.

Overall, the snow depth remains relatively shallow, creating challenging travel conditions and numerous hazards present at or just below the snow surface across all elevations.

Weather Summary

Tuesday Night

Mainly clear skies with no precipitation, southwest alpine winds 30 to 50 km/h, treeline temperature 0 °C, an above freezing layer remains between 1700 and 2500 m overnight.

Wednesday

Mix of sun and cloud with isolated flurries, 2-5 mm accumulation, southwest alpine winds 70 to 100 km/h, treeline temperature 0 °C, freezing levels 1600 m.

Flurries continue overnight bringing another 5 to 10 mm of accumulation.

Thursday

Mainly cloudy with scattered flurries, 2 to 5 mm accumulation, west alpine winds 10 to 30 km/h, treeline temperature -4 °C, freezing levels 800 m.

Friday

Mix of sun and cloud with isolated flurries, trace accumulation, southwest alpine winds 50 to 70 km/h, treeline temperature -2 °C, freezing levels 1000 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Wind slabs are most reactive during their formation.
Surface hoar distribution is highly variable. Avoid generalizing your observations.
Look for signs of instability: whumphing, hollow sounds, shooting cracks, and recent avalanches.
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.

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.