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Avalanche Forecast

Archived

Dec 30th, 2022–Dec 31st, 2022

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

Regions

Sea To Sky, Brandywine, Garibaldi, Homathko, Powell River, Spearhead, Tantalus, Tetrahedron.

The likelihood of human-triggered avalanches will increase as the storm snow settles into a consolidated slab. Be mindful that small avalanches on the surface could step down to weak layers deep in the snowpack.

Confidence

Moderate

Avalanche Summary

Several large (size 2 to 2.5) slab avalanches were produced during explosive control work on Thursday. All in alpine terrain on a variety of aspects. A number of avalanches slid on deep persistent weak layers, with crowns of 1.5 to 2 m deep.

Please continue to post your observations and photos to the Mountain Information Network.

Snowpack Summary

Recent snowfall has been accompanied by moderate to strong southerly winds since Thursday. Below the new snow is a crust at higher elevations, while at lower elevations (below roughly 1600 m) the upper snowpack remains moist. Deeper in the snowpack a series of weak layers exist consisting of crusts, facets, and buried surface hoar.

Total snow depths are roughly 100 to 200 cm at treeline.

Weather Summary

Friday night

Cloudy with snow, 10 to 20 cm. Moderate southwest winds. -5 C at treeline. Freezing levels 1000 m.

Saturday

Cloudy with light snow, 5 to 10 cm. Light southwest winds. -5 to -10 at treeline. Freezing levels 1000 m.

Sunday

Cloudy with periods of sun. No precipitation. Light southwest winds. -5 to -10 C at treeline. Freezing levels 700 m.

Monday

Mostly sunny, with no precipitation. Light southeast winds. -5 C at treeline. Freezing levels 800 m.

Sunday

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
  • Be especially cautious as you transition into wind affected terrain.
  • Storm slabs in motion may step down to deeper layers resulting in large avalanches.

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.

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.