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

Regions

Little Yoho.

An Arctic air mass has moved into the forecast region, bringing temperatures as low as -25°C. When recreating in the backcountry, be prepared for these cold temperatures, as even a minor setback could have serious consequences.

Confidence

High

Avalanche Summary

Minimal natural avalanche activity was observed during a flight across the forecast region on Friday. Avalanche control triggered very few slab avalanches today, with no failures on the deep persistent problem. The majority of results were loose dry avalanches, which entrained the faceted snowpack and ran far down the paths. The largest avalanche was a size 3 on Mount Field.

Snowpack Summary

10 to 15 new today with strong to extreme Thursday have created winds slabs on lee features in the alpine and at treeline. The upper pack may have a thin crust under the new snow on solar aspects and a surface hoar/facet interface under last week's snow, but no avalanches observed on this layer yet. The mid-pack is generally strong; however, a weak facet layer can be found near the ground in shallow snowpack areas. At treeline, average snowpack depth ranges from 120 to 150 cm.

Weather Summary

An Arctic air mass has moved into the forecast region, bringing cold temperatures, clear skies, and light to moderate North winds. Temperatures are expected to drop as low as -25°C over the weekend.

Terrain and Travel Advice

  • Wind slabs are most reactive during their formation.
  • Watch for newly formed and reactive wind slabs as you transition into wind-affected terrain.

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.

Deep Persistent Slabs

Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.