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Avalanche Forecast

Archived

Feb 12th, 2023–Feb 13th, 2023

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

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

Seek out sheltered terrain to avoid wind slabs and find the best riding.

Confidence

Moderate

Avalanche Summary

On Saturday, wind-affected snow was reported to be reactive to skier traffic. A size 2 wind slab avalanche was released on a west aspect at 1700 m as a skier passed over a convex roll. See MIN for photos of the slide. A skier accidental size 1.5 storm slab avalanche was reported on a steep, northeast, treeline feature.

Evidence of several size 3 natural slab avalanches were observed. It is believed these avalanches ran within the storm and were 24 to 40 hours old.

On Friday, local operators were able to trigger a number of storm slab avalanches with explosives. Control work focused on mitigating the overhead hazards that cornices now pose. Make sure to use caution in areas where cornices are present.

Snowpack Summary

By Monday morning 20 cm of new snow will overlie the previously 40-70 cm of recent wind-affected storm snow. As you descend in elevation wind effect decreases and the temperature effect increases and the new snow may overlie a crust.

A series of crusts are found at varying depths throughout the region. A crust from late January is found at all elevations down 40-100 cm with small facets above it. In the Rhododendron and Pemberton Icefield area, this crust has been reactive to skier traffic and in test pits at treeline. In the Brandywine area, a crust found 60-150 cm deep resulted in a handful of surprisingly large rider-triggered avalanches in the past few days. This layer exists to 1900 m.

Total snowpack depths are reaching 300 cm in some areas.

Weather Summary

Sunday Night

Cloudy and snowing, 20-25 cm accumulation. Strong southwest winds easing to 20 km/h by morning. Treeline temperature -3 °C. Freezing levels 1000 m.

Monday

Mostly cloudy, 5-8 cm accumulation. West winds 20 km/h gusting 40 km/h. Treeline temperature -5 °C. Freezing level 800 m.

Overnight cloudy with isolated flurries, 2-5 cm accumulation. Freezing levels drop to valley bottom.

Tuesday

Sunny. Winds north northwest 10 to 15 km/h. Treeline temperature -10 °C. Freezing level 800 m.

Wednesday

Sunny. Winds west 10 to 25 km/h. Treeline temperature -8 °C. Freezing level 500 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
  • Avoid freshly wind loaded features, especially near ridge crests, roll-overs and in steep terrain.
  • Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.

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.