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Avalanche Forecast

Archived

Dec 25th, 2022–Dec 26th, 2022

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.
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.

Heavy precipitation is forecast overnight as freezing levels spike and then cool. Avalanche hazard will peak with the onslaught of 40-70 mm in 24 hrs - either as a storm slab or wet avalanche problem.

Confidence

Moderate

Avalanche Summary

Through Saturday, explosives and skier traffic produced multiple size 1-2 storm slabs in treeline terrain and higher, on average crowns were 30 cm deep. Later in the day skiers remotely triggered (size 1) a re-loaded slope at treeline. Loose wet avalanches were reported below 1700 m.

With heavy precipitation (40-70 mm) forecast overnight along with falling freezing levels, it's possible heavy snowfall could blanket upper elevations and quickly build a reactive slab by Monday morning.

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

Snowpack Summary

Upwards of 40 cm of storm snow over the weekend has been redistributed by strong south winds. Warm temperatures and rain have impacted most elevations, a melt-freeze crust has formed below 1800 m. The new snow covered a layer of weak and unconsolidated snow produced by the recent cold weather.

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

Sunday Night

Rain and wet flurries, 30-40 mm. Ridgeline low temperature 0 C. South wind 50-70 km/hr. Freezing level spiking above 2400 m and dropping to 2000 m by dawn.

Monday

Depending on freezing levels and the snow-rain line, upwards of 50 cm is possible above 2000 m by noon Monday along with strong southwest wind.

Rain and wet snow with cooling through the day, 30-35 mm. Ridgetop high temperature +2 C. Southwest wind 30-50 gusting to 70 km/hr. Freezing level dropping below 1500 m by end of day.

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

Tuesday

Wet flurries, 20-30 mm Ridgetop low temperature - C. Southeast wind 30-50 km/hr. Freezing level 1500 m.

Wednesday

Flurries, 10 cm. Ridgeline high temperature -2 C. Southwest wind 20-40 km/hr. Freezing level falling to valley bottom.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.
  • Be alert to conditions that change with aspect and elevation.
  • The more the snow feels like a slurpy, the more likely loose wet avalanches will become.

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.

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.

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.