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Avalanche Forecast

Archived

Feb 29th, 2024–Mar 1st, 2024

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

Regions

Coquihalla, Harrison-Fraser, Manning, Skagit.

Dangerous avalanche conditions continue. Natural and human-triggered avalanches are likely.

Stick to simple, non-avalanche terrain without exposure to overhead slopes.

Confidence

Moderate

Avalanche Summary

On Wednesday, numerous natural slab avalanches were reported up to size 1. However, the observations were limited due to visibility and suspect an ongoing avalanche cycle had occurred.

Natural, and human-triggered avalanche activity will likely continue on Friday.

Snowpack Summary

Up to 70 cm of storm snow overlies wind-affected surfaces and old wind slabs in exposed areas 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. Although natural avalanche activity may taper out on this layer as the snow stops falling it will remain possible to human-trigger it for some time afterward.

Weather Summary

Thursday Night

Cloudy with snow 5 to 15 cm. Ridgetop wind 25 gusting to 60 km/h southwest ridgetop wind. Treeline temperature -5 °C. Freezing levels valley bottom.

Friday

Cloudy with sunny periods and isolated flurries. 15 to 50 km/h south ridgetop wind. Treeline temperature -3°C. Freezing level 1000 m.

Saturday

Cloudy with snow 5 cm. 15 to 40 km/h southeast ridgetop wind. 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

  • Storm snow and wind is forming touchy slabs. Use caution in lee areas in the alpine and treeline.
  • 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.

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.