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Avalanche Forecast

Archived

Mar 12th, 2023–Mar 13th, 2023

Alpine
Natural and human triggered avalanches likely.
Treeline
Natural and human triggered avalanches likely.
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 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

Coquihalla, Harrison-Fraser, Manning, Skagit.

Part of our region could see up to 45 cm of snow accumulate by noon on Monday.

Reactive storm slabs should be expected.

Confidence

Moderate

Avalanche Summary

A size 2.5 natural glide slab release was reported on Thursday. This avalanche occurred at treeline on a south aspect. No other significant avalanches were reported in the past few days.

Operators in the area reported natural wind slab activity Friday and Saturday. They were on the north and northeast and released at a depth of 10 to 40 cm.

Snowpack Summary

Snow arriving Sunday night will sit on a variety of surfaces. On solar aspects, it may sit on a recently developed sun crust. In sheltered areas, the new snow will bury 10 cm of snow that fell earlier in the week. There are reports of a buried surface hoar layer underneath this layer of recent snow. Strong to moderate south to southwest winds may create new wind slabs at higher elevations. Cornices have also been created.

There are several crusts in the mid/lower snowpack. Their depth ranges from 150 to 250 cm.

A large trigger, such as a cornice fall or a smaller avalanche in motion, could trigger a very large avalanche on one of these deeply buried weak layers. A single rider is unlikely to trigger this layer unless they are in a steep, rocky, and shallow snowpack area.

Weather Summary

Sunday Night

Cloudy, up to 30 cm accumulation mixed with rain, winds southwest 35 km/h gusting to 70, treeline temperatures -5 to 0 °C with freezing levels reaching 1500 m.

Monday

Cloudy, 10 to 15 cm accumulation, winds southwest 30 to 40 km/h gusting to 60, treeline temperatures -7 to -2 °C with freezing levels to 1100 m.

Tuesday

A mix of sun and cloud, trace accumulation, winds southwest 20 to 30 km/h, treeline temperatures around -5 °C with freezing levels going from 300 to 1400 m.

Wednesday

A mix of sun and cloud, trace accumulation, winds westerly 15 to 20 km/h, freezing levels getting up to 1600 m by the end of day.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Watch for changing conditions today, storm slabs may become increasingly reactive.
  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • The more the snow feels like a slurpy, the more likely loose wet avalanches will become.
  • Minimize your exposure time below cornices.
  • Be careful to keep storm day fever from luring you out into bigger terrain features.

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.