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Avalanche Forecast

Archived

Dec 4th, 2023–Dec 5th, 2023

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

Regions

Sea To Sky, South Coast, Brandywine, Garibaldi, Homathko, Powell River, Spearhead, Tantalus, North Shore, Sasquatch, Sasquatch, Sky Pilot, Tetrahedron.

UPDATED 9:51 PST

Avalanche danger will increase Monday as heavy snow and rain add significant load to the meagre snowpack. Minimize your exposure to avalanche terrain.

Confidence

Moderate

Avalanche Summary

We are expecting a natural avalanche cycle as the storm intensifies on Monday.

On Saturday, natural and remotely triggered storm slab avalanches size 1-2 were reported near Whistler, and MIN reports from Cypress, Anif and Red Heather describe whumphing and easy failures in snowpack tests. If you're heading out in the backcountry, please consider sharing any observations on the Mountain Information Network 🙏

Snowpack Summary

Below 1800 m, rain soaks the snowpack while heavy storm slabs build at upper elevations. The new load falls on 30-60 cm of snow from the previous storm, which sits over various layers of crusts and old faceted snow, or directly on the ground. In sheltered areas, recent snow may also contain a layer of large surface hoar crystals (which will be eliminated by the rain if we're lucky). The snow line is likely creeping up as rain washes away lower elevations.

Check out the photos and snowpack description in this MIN from our forecaster field trip to Round Mountain on Sunday!

Weather Summary

A warm, wet storm arrives on Monday, culminating Monday night with heavy precip and positive temperatures up to 3000 m. Very heavy precip like this can bring the snow line several hundred meters below freezing level, so expect a mix of snow and rain. Things start to cool off again on Tuesday.

Sunday night

5-10 cm of new snow. Moderate southwest ridgetop wind. Freezing level 1300 m.

Monday

Mixed precip (25-50 mm). Strong south ridgetop wind. Freezing level spiking to 3000m, snow level around 1800 m.

Tuesday

Heavy precip overnight (50-90 mm), easing and becoming snow in the morning (10-20 mm). Strong southerly ridgetop wind easing to moderate southwest. Freezing level dropping from 3000 m to 1500 m.

Wednesday

A mix of sun and cloud. Calm. Freezing level 1500 m.

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 aware of the potential for larger than expected storm slabs due to the presence of buried surface hoar.
  • Early season avalanches at any elevation have the potential to be particularly dangerous due to obstacles that are exposed or just below the surface.

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.