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Avalanche Forecast

Archived

Mar 13th, 2024–Mar 14th, 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 and human triggered avalanches likely.
Below Treeline
Natural and human triggered avalanches likely.
Alpine
Natural and human triggered avalanches likely.
Treeline
Natural and human triggered avalanches likely.
Below Treeline
Natural and human triggered avalanches likely.

Regions

Glacier.

The strong spring sunshine and rapidly warming temperatures will actively trigger avalanches in the upcoming days. Start your day early, and scale back your exposure as the temperatures rise.

Remote and step down triggering of large avalanches is still a concern, with a robust crust/facet combo lurking ~1m below the surface.

Confidence

Moderate

Avalanche Summary

A field team in the Bonney area Wednesday observed several loose snow avalanches up to size 2.5, from the steep solar slopes of Ross Peak and Mt. Green.

Early this week, wind spikes triggered numerous avalanches up to sz 3, believed to be running in the new storm snow or on the reloaded Feb 3 bed surface.

Last Thursday, we observed naturally-triggered size 3 slab avalanches from Catamount Mtn SE face and Mt. Leda NE face. These were both deep, likely failing on the Feb 3rd crust.

Snowpack Summary

30-40cm of recent storm snow has been blown into a slab by strong Southwest winds in exposed areas. This new snow rests on a variety old surfaces, most importantly a thin suncrust on South & West aspects.

80-140cm of settled snow sits atop a sugary facet layer. These facets are not bonding well to the widespread, very firm crust from Feb 3rd. This crust is a significant persistent weak layer and will be a significant layer of concern for the foreseeable future.

Weather Summary

A ridge builds over BC, resulting in clearing skies, slackening winds, and rising freezing levels (FZL).

Tonight: Clear periods. Alpine low -9°C. Freezing level (FZL) 500m. Light W ridgetop winds.

Thurs: Sun/cloud. Alpine high -3°C, FZL 1500m. Light W winds.

Fri: Sun/cloud, Low -2°C, High 4°C. Temperature inversion. Light N winds. FZL 2500m

Sat: Sun/cloud. Low 3°C, High 4°C. FZL 3200m. Light ridge winds.

Terrain and Travel Advice

  • Use conservative route selection. Choose simple, low-angle, well-supported terrain with no overhead hazard.
  • Avoid exposure to steep sun exposed slopes.
  • A moist or wet snow surface, pinwheeling and natural avalanches are all indicators of a weakening snowpack.
  • If triggered loose wet avalanches may step down to deeper layers resulting in larger avalanches.

Problems

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.

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.