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Avalanche Forecast

Archived

Jan 18th, 2025–Jan 19th, 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.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely.
Below Treeline
Natural avalanches unlikely.

Regions

Purcells, Crawford, Dogtooth, East Purcell, West Purcell.

Seek out wind sheltered terrain below treeline for the softest snow and lowest hazard.

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

Confidence

Moderate

Avalanche Summary

On Thursday and Friday, 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 forward, we suspect wind slabs will remain possible to trigger, especially where they overlie a layer of surface hoar.

Snowpack Summary

Recent strong to extreme winds from shifting directions have created wind slabs of varying hardness and thickness on lee slopes. These slabs may be overlying a variety of surfaces, including sun crust, surface hoar, and facets.

A surface hoar layer from early January, buried 20–40 cm deep, may be reactive to human triggers, particularly where it is covered by a wind slab.

A persistent weak layer of facets buried in early December is on average 60 to 90 cm deep. In areas near Invermere this layer may only be buried 30 cm. Triggering this layer remains possible in isolated areas.

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

Weather Summary

Saturday Night

Partly cloudy. 30 to 50 km/h northwest ridgetop wind. Treeline temperature -18 °C.

Sunday

Sunny. 20 to 40 km/h north ridgetop wind. Treeline temperature -19 °C.

Monday

Sunny. 50 km/h northwest ridgetop wind. Treeline temperature -20 °C.

Tuesday

A mix of sun and cloud. 60 km/h west ridgetop wind. Treeline temperature -16 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Carefully evaluate steep lines for wind slabs.
  • Avoid steep, rocky, and wind-affected areas where triggering slabs is more likely.
  • Be aware of the potential for large avalanches due to buried weak layers.
  • Seek out wind sheltered terrain below treeline where you can avoid wind slabs and find great riding.

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.