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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 and human triggered avalanches likely.
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

South Coast Inland, Birkenhead, Duffey, South Chilcotin, Stein, Taseko.

The snowpack is not to be trusted right now, especially if the sun pokes out. Surface instabilities and deeply buried weak layers have combined to create dangerous avalanche conditions.

Confidence

Moderate

Avalanche Summary

Operators in the Chilcotins continue to report new persistent slab avalanches running on our buried facet/crust interface, generally to size 2.5. On Monday, two such releases were remote triggered on north aspects from 150 m to 250 m away, one of them a size 3 (very large).

Several size 2 human-triggered avalanches were reported over the weekend. They occurred both within storm snow layers (40 to 60 cm deep) and on the persistent weak layer (100 cm deep).

Snowpack Summary

Roughly 10-15 cm of new snow through Tuesday morning brought 4-day storm totals in the region to 40 to 60 cm, with alpine terrain heavily wind-affected. Storm snow covers a variety of layers including surface hoar in isolated shady areas.

A weak layer composed of weak faceted grains on a crust is now buried 80 to 150 cm deep. This layer remains sensitive to both human and natural triggers and continues to produce large, destructive avalanches.

The mid and lower snowpack below this layer is well-settled and strong.

Weather Summary

Tuesday night

Cloudy with isolated flurries. 10 - 15 km/h southwest ridgetop wind. Freezing level to valley bottom.

Wednesday

A mix of sun and cloud. 10 km/h southwest or northwest ridgetop wind. Treeline temperature -2 °C with freezing level rising to 1500 m.

Thursday

Sunny. 10 km/h southwest or northwest ridgetop wind. Treeline temperature +4 °C with freezing level rising to 3200 m.

Friday

Sunny. 5 km/h variable ridgetop wind. Treeline temperature +9 with freezing level to 3400 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Remote triggering is a concern, watch out for adjacent and overhead slopes.
  • Storm slabs in motion may step down to deeper layers resulting in large avalanches.
  • Back off slopes as the surface becomes moist or wet with rising temperatures.

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.

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.