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Avalanche Forecast

Archived

Mar 20th, 2024–Mar 21st, 2024

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

Regions

Kootenay Boundary, Bonnington, Grohman, Kootenay Pass, Norns, Rossland, Ymir, Crawford, Moyie, St. Mary, Kokanee, Valhalla.

While conditions are gradually improving with cooling temperatures, very large persistent slab avalanches may remain triggerable in areas not capped by a thick surface crust.

Confidence

Moderate

Avalanche Summary

A natural avalanche cycle that continued into Tuesday saw numerous loose wet avalanches up to size 3 (very large) as well as cornice failures up to size 2, on sunny aspects at all elevations.

Snowpack Summary

A skiff of new snow now sits over predominantly crusty surfaces. Dry snow may be found on high north aspects in the alpine, and moist surfaces may persist at low elevations.

A weak layer of surface hoar is buried 40-60 cm deep in isolated, sheltered areas. A widespread crust with sugary facets above is buried 80-200 cm deep. Both of these layers remain primary concerns for triggering large persistent slab avalanches.

Weather Summary

Wednesday night

Increasing cloud, flurries starting, up to 5 cm. 20 to 30 km/h northwest ridgetop wind. Treeline temperature -2 °C. Freezing level 1500 m.

Thursday

Mostly cloudy with isolated flurries, up to 5 cm of snow. 20 to 30 km/h northwest ridgetop wind. Treeline temperature -1 °C. Freezing level 1900 m.

Friday

Mostly cloudy. 10 to 20 km/h southeast ridgetop wind. Treeline temperature -1 °C. Freezing level 1900 m.

Saturday

Cloudy with isolated flurries, around 5 cm of snow. 20 to 30 km/h northeast ridgetop wind. Treeline temperature -3 °C. Freezing level 1600 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Avalanche hazard may have improved, but be mindful that deep instabilities are still present.
  • Keep in mind that human triggering potential persists as natural avalanching tapers off.
  • Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
  • If triggered loose wet avalanches may step down to deeper layers resulting in larger avalanches.
  • When a thick, melt-freeze surface crust is present, avalanche activity is unlikely.

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.