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Avalanche Forecast

Archived

Mar 17th, 2024–Mar 18th, 2024

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

Regions

Northwest Inland, Kispiox, Microwave-Sinclair, North Bulkley, South Bulkley, South Bulkley, South Bulkley, Telkwa.

Conservative decision-making is essential following a period of intense warming.

A buried weak layer in the snowpack could produce very large avalanches.

Confidence

Moderate

Avalanche Summary

Large natural persistent slab avalanches (up to size 2.5) were reported on Friday. Pinwheeling and loose wet activity also occurred.

Over the last week, skiers were surprised by large avalanches; several were remotely triggered from a distance from low-angle or flat terrain. These avalanches failed on the buried weak layer described in the snowpack summary.

Snowpack Summary

Expect a surface crust at most elevations. Where the snow still feels wet, or like a slushie, avalanches are more likely to still occur.

A layer of weak, faceted crystals over a crust, or surface hoar, is the primary layer of concern, buried around 40 to 80 cm deep. This layer has produced large avalanches, especially at treeline and below, during the last week.

Weather Summary

Sunday Night

Increasing cloud. 40 to 50 km/h west ridgetop wind. Treeline temperatures 0 °C. Freezing level drops to 1000 m.

Monday

Partly cloudy. 20 to 30 km/h northwest ridgetop wind. Treeline temperatures +2 °C. Freezing level 1500 m.

Tuesday

Partly cloudy. 20 to 30 km/h east ridgetop wind. Treeline temperatures +2 °C. Freezing level 1500 m.

Wednesday

Cloudy with 5 to 10 cm of snow. 30 to 40 km/h east ridgetop wind. Treeline temperatures -1 °C. Freezing level 900 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Avoid exposure to overhead avalanche terrain as temperatures increase.
  • A moist or wet snow surface, pinwheeling and natural avalanches are all indicators of a weakening snowpack.
  • Cornices become weak with daytime heating or solar exposure.

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.

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.