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Avalanche Forecast

Archived

Feb 17th, 2024–Feb 18th, 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, Flathead, Lizard.

Slab avalanches have been reactive to human triggers. This is most likely where the snow is wind affected.

Choose smaller test slopes before committing to large features.

Confidence

Moderate

Avalanche Summary

On Friday and Saturday near Fernie, a couple of small (size 1) rider-triggered wind slab avalanches were reported.

On Thursday, three large (size 2) explosive triggered persistent slab avalanches were reported. These avalanches failed on the February melt freeze crust, 60 cm deep.

Snowpack Summary

Alpine and open treeline terrain is generally wind-affected. In wind sheltered areas, 30 to 60 cm of settling snow sits on the rain crust formed in early February. In some places, weak, sugary crystals (facets) are starting to form over the crust.

There are crusts and facets in the mid and lower snowpack but they have not produced any recent avalanches.

Weather Summary

Saturday Night

Clear. No new snow expected. Light southwest ridgetop wind. Treeline temperature around -5 °C.

Sunday

Partly cloudy. No new snow expected. Light west or southwest ridgetop wind. Treeline temperature around -7 °C.

Monday

Mostly cloudy. 0-1 cm of snow expected. Light southwest ridgetop wind. Freezing level to 1000 m. Treeline temperature around -7 °C.

Tuesday

Mostly cloudy. 1-5 cm of snow expected. Light to moderate southwest ridgetop wind. Freezing level rising to 1500 m. Treeline temperature around -5 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Keep in mind that human triggering potential persists as natural avalanching tapers off.
  • Keep in mind the crust offers an excellent bed surface for avalanches.
  • Carefully evaluate steep lines for wind slabs.

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.