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Avalanche Forecast

Archived

Feb 20th, 2024–Feb 21st, 2024

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.
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, Powell River, Spearhead, Tantalus, Sky Pilot.

Assess for slab properties as you move through terrain.

Rider triggerable slabs are possible where a slab overlies facets, surface hoar or a crust.

Confidence

Moderate

Avalanche Summary

Over the past week we have seen a pattern of human and remotely triggered size 1 to 1.5 wind slab avalanches with a few being up to size 2. Human-triggered avalanches have occurred on a range of aspects. Slabs have been averaging 20 - 30 cm thick, with some failing on buried surface hoar and propagating widely.

Snowpack Summary

Up to 20 cm of new snow could accumulate over a variety of surfaces including; a crust on south aspects and all aspects at lower elevation, Surface hoar in sheltered features and previously wind effected surfaces in exposed terrain.

30 to 40 cm of snow sits above large surface hoar and/or faceted crystals at treeline and above. This is most problematic in places where wind slabs have formed over it. A widespread, supportive crust exists 30 to 60 cm below the surface. It is an excellent bed surface for slabs run to on.

The snowpack is well bonded and strong below this crust.

Weather Summary

Tuesday Night

Mostly cloudy with 5 to 10 cm of new snow expected. 15 to 30 km/h south alpine wind. Treeline temperature -2°C.

Wednesday

Mostly cloudy with 5 to 10 cm of new snow expected. 15 to 30 km/h southeast alpine wind. Freezing level rising to 1700 m.

Thursday

Mostly cloudy with around 5 cm of new snow expected. 5 to 15 km/h southeast alpine wind. Freezing level rising to 1500 m.

Friday

Mostly sunny with trace amounts of new snow possible. 30 to 50 km/h southwest alpine wind. Freezing level rising to 1700 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • The best and safest riding will be on slopes that have soft snow without any slab properties.
  • Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.

Problems

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.

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.