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Avalanche Forecast

Archived

Jan 17th, 2025–Jan 18th, 2025

Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely.
Below Treeline
Natural avalanches unlikely.

Regions

Purcells, Dogtooth, East Purcell, West Purcell.

Wind slabs continue to be observed in the region.

Use extra caution in wind-affected terrain and continue to avoid steep, rocky slopes with shallow snow cover.

Confidence

Moderate

Avalanche Summary

On Thursday, several size 1-2 wind slab avalanches were reported across the Eastern Purcells.

On Monday several human-triggered and natural avalanches were reported in the Jumbo area west of Invermere.

Looking to the weekend, we suspect wind slabs to remain possible to trigger, especially where they overlie a layer of surface hoar.

Snowpack Summary

A thin layer of recent snow has covered a variety of surfaces, including sun crust, surface hoar, and wind-affected snow. Recent winds have varied in direction, forming wind slabs on lee slopes.

Older wind slabs may still be found near ridgetops covering a 20 to 30 cm deep surface hoar layer from early January. These slabs may remain sensitive for an extended period.

A weak layer of facets buried in early December is on average 60 to 90 cm deep. In the shallower eastern parts of the Purcells, this layer may only be 30 cm deep. This layer continues to cause sporadic large avalanches.

The snowpack base consists of a thick crust and facets in many areas.

Weather Summary

Friday Night

Partly cloudy. 15 to 30 km/h northwest ridgetop wind. Treeline temperature -16 °C.

Saturday

Mostly sunny. 5 to 15 km/h variable ridgetop wind. Treeline temperature -20 °C.

Sunday

Mostly sunny. 15 to 20 km/h north ridgetop wind. Treeline temperature -21 °C.

Monday

Sunny. 10 km/h west ridgetop wind. Treeline temperature -18 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Avoid steep, rocky, and wind-affected areas where triggering slabs is more likely.
  • Pay attention to isolated wind affected features in the alpine, as well as cross-loaded features at treeline.
  • Be aware of the potential for large avalanches due to buried weak layers.

Problems

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind 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.