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Avalanche Forecast

Archived

Dec 24th, 2022–Dec 25th, 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 and human triggered avalanches likely.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches possible, human triggered probable.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches possible, human triggered probable.

Regions

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

Avalanche hazard will remain elevated with continued precipitation, strong wind, and rising freezing levels.

Confidence

Moderate

Avalanche Summary

This MIN from Saturday documents a small skier-triggered avalanche and a natural slab avalanche in the Callaghan Lakes area.

Early reports Saturday documented wet loose avalanches up to 1700 m.

On Friday, explosives triggered size 1-1.5 slab avalanches up to 30 cm deep.

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

Snowpack Summary

In the last 48 hours, 30-45 cm of new snow covered a layer of weak and unconsolidated snow produced by the recent cold weather. Steady southwest winds have produced deeper depositions around ridges and in wind-loaded terrain. Rain and rising freezing levels have turned snow moist at lower elevations.

A number of layers persist deeper in the snowpack, consisting of facets, surface hoar, and crusts. Most recently, these layers have been unreactive and this heavy load of new snow should provide insight into any deeper instabilities. Total snow depths are roughly 90-140 cm at treeline and up to 200 cm in the alpine.

Weather Summary

Saturday night

Flurries, 5 cm. Ridgetoplow temperature -4 C. Southwest wind 25-35 km/hr. Freezing level 1000 m.

Sunday

Continued precipitation and rising freezing levels will produce a variety of frozen water forms including freezing rain at roadside elevations.

Flurries and wet snow transitioning to rain, 10 mm. Ridgetop high temperature 0 C. Southwest wind 30-60 km/hr. Freezing level rising above 2000 m.

Monday

Heavy rain with freezing levels spiking above 2500 m, 25 mm overnight and another 15 mm through the day. Ridgetophigh temperature +2 C. South wind 50-70 km/hr.

Tuesday

Wet flurries transitioning to snow: 12 mm overnight and another 15 mm through the day. Ridgetop low temperature -2 C. Southwest wind 30-50 km/hr. Freezing level 1500 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Minimize exposure during periods of heavy loading from new snow, wind or rain.
  • Be alert to conditions that change with aspect and elevation.
  • Carefully monitor the bond between the new snow and old surface.
  • The more the snow feels like a slurpy, the more likely loose wet avalanches will become.

Problems

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.

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.