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Avalanche Forecast

Archived

Feb 27th, 2024–Feb 28th, 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 and human triggered avalanches likely.
Treeline
Natural and human triggered avalanches likely.
Below Treeline
Natural and human triggered avalanches likely.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches possible, human triggered probable.

Regions

Kootenay Boundary, Bonnington, Grohman, Kootenay Pass, Norns, Rossland, Ymir, Crawford, Moyie, St. Mary, Kokanee, Valhalla.

Natural and human-triggered avalanches are likely with the arrival of more snow and wind on Wednesday.

Confidence

Moderate

Avalanche Summary

Several remotely triggered avalanches up to size 3 have been reported through the region since the weekend. These avalanches have occurred at various elevations and have been triggered from as far as 100 m away. It is suspected that these slides have occurred on the buried crust/facet layer. Check out this MIN report.

A natural size 3 avalanche was reported in the Nelson area, sliding on the same crust/facet layer. It occurred in alpine terrain in wind-loaded terrain.

Snowpack Summary

Approximately 30 to 50 cm of recent snow has buried a variety of layers that may prolong the bonding time. These layers include sun crusts on south-facing slopes and faceted snow or surface hoar in sheltered, north-facing terrain.

A widespread crust exists down roughly 50 to 80 cm. In many areas, small, weak faceted grains have formed just above or below this crust.

The lower snowpack is generally well-settled and strong.

Weather Summary

Tuesday Night

Mostly cloudy with 5 to 10 cm of snow. 20 to 40 km/h southwest ridgetop wind. Treeline temperature -12 °C.

Wednesday

Cloudy with 5 to 15 cm of snow. 30 to 50 km/h southwest ridgetop wind. Treeline temperature -5 °C. Freezing level 1500 m.

Thursday

Cloudy with 10 to 20 cm of snow. 30 to 50 km/h southwest ridgetop wind. Treeline temperature -5 °C. Freezing level 1500 m.

Friday

Mostly cloudy with 2 to 10 cm of snow. 20 to 40 km/h southwest wind. Treeline temperature -7 °C. Freezing level 1000 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Make conservative terrain choices and avoid overhead hazard.
  • Remote triggering is a concern, watch out for adjacent and overhead slopes.
  • Storm slab size and sensitivity to triggering will likely increase through the day.

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.