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Avalanche Forecast

Archived

Feb 21st, 2024–Feb 22nd, 2024

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

Regions

Lizard-Flathead, South Rockies, Akamina, Flathead, Lizard, Bull, Crowsnest North, Crowsnest South, Elkford East, Elkford West.

Recent avalanches in the region indicate that the potential for rider triggering remains possible.

Confidence

Moderate

Avalanche Summary

On Wednesday, several explosive controlled avalanches sizes 1.5 to 2, were failing on the new storm snow in the Lizard Range.

On Tuesday, a skier accidentally triggered a small (size 1) avalanche on the persistent layer described in the snowpack summary.

On Monday, a group of skiers triggered a persistent slab, for details check this MIN. Explosive control also produced a large persistent slab avalanche that failed on faceted snow above the early February rain crust.

Snowpack Summary

5 to 13 cm of snow recently fell across the region. This new snow may have been blown onto lee slopes creating wind slabs. Otherwise, the new snow sits on previously wind-affected or crusty surfaces. In wind-sheltered areas, 30 to 60 cm of settled snow sits above a 10-20 cm thick, rain crust that formed in early February. This crust remains a concern due to a layer of facets that have formed overtop, making it susceptible to human triggering.

Weather Summary

Wednesday Night

Cloudy with 1 to 2 cm of snow, 15 to 25 km/h southwest ridgetop wind, treeline temperature around -2 °C, freezing level dropping to valley bottom.

Thursday

Mostly cloudy with 0 to 2 cm of snow / light rain, 25 km/h southwest ridgetop wind, treeline temperature around 0 °C, freezing level rising to 1700 m.

Friday

A mix of sun and cloud with trace amounts of snow / light rain, 30 km/h southwest ridgetop wind, treeline temperature around 0 °C, freezing level rising to 1600 m.

Saturday

Partly cloudy with 2 to 6 cm of snow / light rain, 30 to 40 km/h southwest ridgetop wind, treeline temperature around 0 °C, freezing level rising to 1600 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Fresh snow rests on a problematic persistent slab, don't let good riding lure you into complacency.
  • Watch for wind-loaded pockets especially around ridgecrest and in extreme terrain.
  • Keep in mind that human triggering potential persists as natural avalanching tapers off.

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.