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Avalanche Forecast

Archived

Dec 20th, 2024–Dec 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, 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

Lizard-Flathead, Flathead, Lizard.

Wind-loaded terrain will be the main concern at upper elevations, while the potential for buried surface hoar necessitates caution in steep openings at treeline and below.

Confidence

Moderate

Avalanche Summary

A widespread natural avalanche cycle took place during the storm on Wednesday.

On Thursday, explosive control near Fernie produced several storm and wind slabs up to size 2. A notable sled-triggered wind slab was reported at Coal Creek from a ridgetop, wind-loaded feature. More details can be seen here.

Snowpack Summary

Recent snowfall has brought up to 40 cm of snow, with deeper deposits accumulating in lee-facing terrain at higher elevations due to southwest winds.

The mid and lower snowpack is generally well-settled and stable. However, there is some uncertainty about a potential surface hoar layer buried 50 to 80 cm deep, which could be reactive on isolated, steep, sheltered slopes around treeline and below.

Snow depths at treeline range from 120 to 180 cm.

Weather Summary

Friday Night

Cloudy with isolated flurries. 20 to 60 km/h southwest ridgetop wind. Treeline temperature 0 °C.

Saturday

A mix of sun and cloud with isolated flurries. 15 to 40 km/h southwest ridgetop wind. Treeline temperature 0 °C. Freezing level 2200 m.

Sunday

Mostly cloudy with up to 2 cm of new snow. 20 to 50 km/h southwest ridgetop wind. Treeline temperature -2 °C.

Monday

Cloudy with up to 2 cm of new snow. 20 to 50 km/h southwest ridgetop wind. Treeline temperature -2 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Be careful with wind-loaded pockets, especially near ridge crests and rollovers.
  • Look for signs of instability: whumphing, hollow sounds, shooting cracks, and recent avalanches.
  • Approach steep and open slopes at and below treeline cautiously, as buried surface hoar may exist.

Problems

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.