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Avalanche Forecast

Archived

Dec 6th, 2024–Dec 7th, 2024

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

Regions

Coquihalla, Manning, Skagit.

630 am update: Avalanche conditions will deteriorate on Saturday as a wet storm arrives.

If you see more than 30 cm of new snow at treeline, treat avalanche danger as HIGH.

Confidence

Low

Avalanche Summary

No recent avalanche activity has been reported.

On Saturday, we can expect to see natural loose wet and storm slab avalanches during the storm.

If you are going out in the backcountry, please consider filling out a Mountain Information Network (MIN) report.

Snowpack Summary

By mid-morning, heavy, wet snow begins to accumulate at upper elevations. Any old surface layers such as facets, surface hoar or thin crusts have likely been neutralized by the rainy start to the storm. Below 1000 m, rain soaks an already moist upper snowpack.

The mid and lower snowpack is generally well-settled and bonded.

Snow depths at treeline vary across the region. Around 90 cm is reported in the Coquihalla and 50 cm near Manning Park.

Weather Summary

Friday Night

Increasing cloud, light rain starting in early am. 50 to 70 km/h southwest ridgetop wind. Treeline temperature +4 °C. Freezing level dropping 3000 m to 2500 m.

Saturday

Rain turning to wet snow, 10 to 30 cm accumulation. 40 to 60 km/h southest ridgetop wind. Treeline temperature 0 °C. Freezing level dropping 2500 m to 1000 m.

Sunday

10 to 20 cm of snow. 20 to 40 km/h northwest ridgetop wind. Treeline temperature -4 °C. Freezing level 1000 to 1300 m.

Monday

A mix of sun and cloud. 10 to 20 km/h northwest ridgetop wind. Treeline temperature -5 °C. Freezing level 500 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Watch for rapidly changing conditions during periods of heavy loading from new snow, wind, or rain.
  • Watch for fresh storm slabs building throughout the day.
  • As the storm slab problem worsens, the easy solution is to choose more conservative terrain.
  • Keep in mind that the high density of wet avalanches can make them destructive.

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.