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Avalanche Forecast

Archived

Mar 12th, 2024–Mar 13th, 2024

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

Regions

Northwest Coastal, Boundary, Kitimat, Nass, Rupert, Seven Sisters, Shames, Stewart, Howson, Ningunsaw, Ningunsaw, Ningunsaw.

Surprising skier-triggered avalanches, including some step-down, are evidence of reactive persistent slabs. Keep choosing low-consequence slopes with no overhead hazard.

Confidence

Moderate

Avalanche Summary

Large and very large slabs and accidentally triggered avalanches continue to occur across the region. On Monday, numerous surprising avalanches were skier-triggered at treeline, including a step-down. Some have been triggered from low-angle terrain onto adjacent slopes. We expect the potential for riders to trigger avalanches will remain elevated over the following days.

For more information, click on the photos below.

Snowpack Summary

Recent storm snow, now totalizing 40 to 80 cm, has formed reactive slabs across the region. Several persistent weak layers are now buried between 80 and 160 cm deep, including hard crusts with overlying weak facets and surface hoar. These weak layers have been responsible for continued avalanche activities over the last week.

At lower elevations, the upper snowpack may be moist or crusty.

Weather Summary

Tuesday Night

Cloudy with 2 of new snow expected. 30 to 40 km/h south ridgetop wind. Treeline temperatures around 0 °C. Freezing level returning to valley bottom.

Wednesday

Cloudy with 3 to 5 cm of new snow expected. 50 to 70 km/h southwest ridgetop wind. Treeline temperatures around 0 °C. Freezing level rising to 1200 m.

Thursday

Cloudy with 10-20 cm of new snow expected. 60 to 80 km/h southwest ridgetop wind. Treeline temperatures around +3 °C. Freezing level rising to 1500 m.

Friday

Cloudy with no precipitation. 40 to 60 km/h southwest ridgetop wind. Treeline temperatures around +5 °C. Freezing level rising to 2500 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Remote triggering is a big concern, be aware of the potential for wide propagations and large, destructive avalanches at all elevations.
  • Back off if you encounter whumpfing, hollow sounds, or shooting cracks.
  • Avoid open slopes and convex rolls at and below treeline where weak layers may be preserved.

Problems

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.

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.