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Avalanche Forecast

Archived

Mar 1st, 2024–Mar 2nd, 2024

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 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.

Regions

Coquihalla, Harrison-Fraser, Manning, Skagit.

While danger ratings are dropping and natural activity may stop, human triggering is still likely

Stick to conservative terrain, avoid large slopes and overhead hazard

Confidence

Moderate

Avalanche Summary

Avalanche activity was observed Thursday to size 2.5, with the largest slabs reported from wind loaded features. Observations are currently limited, however we expect rider triggering is still likely.

Snowpack Summary

Up to 90 cm of recent snow has been heavily wind affected in exposed terrain. Storm snow sits over wind-affected surfaces and 30 to 60 cm of settling snow in sheltered areas.

Multiple weak layers exist in the upper and mid snowpack. The most concerning weak layer is a widespread crust found down 60 to 100 cm, with weak, faceted snow immediately above it. This layer will need time to adjust to the new snow load.

The storm snow and buried weak layers have produced recent large avalanche activity. Although natural avalanche activity may taper off, it will remain possible to human-trigger it for some time afterward.

Weather Summary

Friday Night

Partly cloudy with 5-10 cm of snow possible early evening. 20-40 km/h southerly winds, Freezing level 1000 m.

Saturday

Cloudy with 5 cm of snow possible, and afternoon sun. 30-40 km/h southerly winds. Treeline temperature -5 °C. Freezing level hovers around 700 m.

Sunday

Cloudy with sunny periods and isolated flurries. Light southeast ridgetop wind. Treeline temperature -6 °C. The freezing level hovers around 900 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.
  • Remote triggering is a concern, watch out for adjacent and overhead slopes.
  • Brief periods of sun could quickly initiate natural avalanche activity.
  • Storm slabs in motion may step down to deeper layers resulting in large avalanches.

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.

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.