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Avalanche Forecast

Archived

Feb 5th, 2025–Feb 6th, 2025

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

Regions

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

Choose mellow terrain and watch for signs of instability like whumpfs, shooting cracks or recent avalanches.

Check out the Forecaster Blog "Keeping a Conservative Mindset"

Confidence

Moderate

Avalanche Summary

On Tuesday, several small to large (up to size 2) human triggered avalanches were reported. See this MIN for an example. Most of these avalanches failed on a layer of surface hoar buried at the end of January, and involved the recent storm snow, or associated wind slabs.

We expect human triggered avalanches like these to remain likely for the next few days.

Snowpack Summary

Storm snow totals range from 30 to 60 cm. Deeper deposits are found in wind-loaded areas. The new snow is bonding poorly to old surfaces, which include melt-freeze crusts on sun-exposed slopes, surface hoar or facets on shaded slopes, and wind-affected snow in exposed terrain.

A weak layer of surface hoar buried, 30 to 80cm deep, has been the culprit of many natural and human-triggered avalanches this week. Where this layer is preserved it will remain reactive to human triggering.

The lower snowpack is strong and bonded.

Weather Summary

Wednesday Night

Mostly cloudy. Up to 2 cm of snow. 5 to 10 km/h west ridgetop wind. Treeline temperature -14 °C.

Thursday

A mix of sun and cloud. Light variable ridgetop wind. Treeline temperature -13 °C.

Friday

Sunny. 5 to 15 km/h northeast ridgetop wind. Treeline temperature -13 °C.

Saturday

Partly cloudy. 10 to 20 km/h SW ridgetop wind. Treeline temperature -15 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Closely monitor how the new snow is bonding to the old surface.
  • Fresh snow rests on a problematic persistent slab, don't let good riding lure you into complacency.
  • Be aware of the potential for remote triggering and large avalanches due to buried surface hoar.
  • Be aware of the potential for loose avalanches in steep terrain where snow hasn't formed a slab.

Problems

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.