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Avalanche Forecast

Archived

Feb 22nd, 2024–Feb 23rd, 2024

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 and human triggered avalanches likely.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.

Regions

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

Expect deeper, more reactive new snow in the lee of ridges and exposed terrain features. Make a plan to step back from bigger terrain as winds increase over the day.

Confidence

Moderate

Avalanche Summary

Wednesday's reports showed 5-10 cm in the Whistler area yielding small slab and dry loose results with ski cuts and explosives control. Slabs were more restricted to north aspects.

The previous week had a more sporadic pattern of wind slabs on a range of aspects. These were triggered on buried persistent weak layers of facets and more isolated surface hoar.

There remains uncertainty about the possibility for larger surface avalanches to step down to these weak layers.

Snowpack Summary

10-20 cm of recent snow now overlies a mix of previous surfaces that includes crust on south aspects and on all aspects at lower elevations, faceted snow and/or small surface hoar in sheltered features, and previously wind-affected surfaces in the open. Areas where wind loading has increased the depth of new snow and where larger preserved surface hoar is buried are the most concerning.

30 to 40 cm of snow sits above an older layer of faceted snow or more isolated surface hoar at treeline and above. Just below it, a widespread, thick crust is about 30 to 60 cm deep. This problematic combination remains a concern as it adjusts to the load above it.

The snowpack is well bonded and strong below this crust.

Weather Summary

Thursday night

Cloudy with isolated flurries. 5 to 15 km/h southwest alpine wind, increasing. Freezing level around 1400 m.

Friday

Cloudy. 15 to 35 km/h southwest alpine wind, increasing. Treeline temperature -2 °C with freezing level to 1400 m.

Saturday

Cloudy with flurries bringing about 5 cm of new snow, including overnight amounts. 25 to 35 km/h southwest alpine wind. Treeline temperature -4 °C with freezing level to 1200 m.

Sunday

Cloudy with moderate to heavy snowfall bringing 20 - 30 cm of new snow, including overnight amounts. 40-65 km/h southwest alpine winds, increasing. Treeline temperature -4 with freezing level to 1100 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Wind slabs are most reactive during their formation.
  • If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.

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.