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Avalanche Forecast

Archived

Mar 11th, 2024–Mar 12th, 2024

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

Regions

Coquihalla, Manning, Skagit.

New snow and wind are causing dangerous avalanche conditions. Stick to smaller, low-angle slopes.

Confidence

Moderate

Avalanche Summary

Minimal avalanche activity has been reported in this region. On Sunday, a small (size 1) storm slab avalanche was triggered by riders at Coquihalla Summit.

Snowpack Summary

Storm slabs will grow with another pulse of snow and wind expected on Tuesday. Prior to this snow, a thin crust layer was reported 20 cm deep on south-facing and below treeline elevations.

A few concerning weak layers exist 80 to 120 cm deep including facets on a crust and, in some areas, surface hoar. While we have not had recent reports of persistent slab avalanches in this region, these layers should not be trusted based on notable activity in neighbouring regions.

Weather Summary

Monday Night

Flurries with 5 to 15 cm of snow. 50 km/h southwest ridgetop wind. Treeline temperature -5 °C.

Tuesday

Flurries with 10 to 20 cm of snow. 50 km/h southwest ridgetop wind. Treeline temperature -5 °C.

Wednesday

Light flurries with 2 to 5 cm of snow overnight then mostly cloudy during the day. 20 km/hr west wind. Treeline temperature -4 °C with freezing level rising to 1200 m.

Thursday

Sunny. 15 km/hr northwest wind. Treeline temperature +5 °C with freezing level rising to 3000 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Minimize exposure during periods of heavy loading from new snow and wind.
  • Choose low-angled, sheltered terrain where new snow hasn't been wind-affected.
  • Carefully monitor the bond between the new snow and old surface.
  • In times of uncertainty conservative terrain choices are our best defense.

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.