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Avalanche Forecast

Archived

Feb 16th, 2024–Feb 17th, 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, Spearhead, Tantalus.

Keep your guard up! This isn't your typical 2-3 day wind slab problem. Slabs have formed over a dangerous mix of weak grains and Saturday's warming may increase their reactivity.

Confidence

High

Avalanche Summary

A combination of transportable snow, elevated winds, and weak grains sitting on the hard early February crust has led to a steady stream of small (size 1 to 1.5) and a few large (size 2) wind slab avalanche reports over the past few days. Natural avalanches have triggered on leeward slopes by wind transport but 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.

Snowpack Summary

Sun and wind are creating variable surface conditions. Exposed terrain is being scoured by northeast wind and forming wind slabs on south and west facing slopes.

Roughly 30 cm of snow sits above large surface hoar and/or faceted crystals at treeline and above. A widespread, supportive crust exists 30 to 40 cm below the surface. It is an excellent bed surface for slabs to form over.

The snowpack well bonded and strong below this crust.

Weather Summary

Friday night

Clear. Southeast alpine wind 30-35 km/h. Freezing level remaining near 1400 m.

Saturday

Increasing high cloud. Southeast alpine winds 20 - 30 km/h. Treeline temperature +2 °C with freezing level reaching 2000 m.

Sunday

Cloudy with flurries bringing up to 5 cm of new snow, light rain below about 1300 m. Southeast alpine winds 25 - 35 km/h. Treeline temperature -2 °C with freezing level around 1400 m.

Monday

Mainly cloudy with isolated flurries. East alpine wind 10 - 20 km/h. Treeline temperature -2°C with freezing level around 1400 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Recent wind has varied in direction so watch for wind slabs on all aspects.
  • Wind slabs may be poorly bonded to the underlying crust.
  • Back off slopes as the surface becomes moist or wet with rising temperatures.

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.

Loose Wet

Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.