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Avalanche Forecast

Archived

Jan 16th, 2025–Jan 17th, 2025

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

Little Yoho.

Mt. Field, Mt. Stephen, and Mt. Dennis avalanche closure zones are CLOSED on Friday, January 17th.

New windslab development in the alpine down into treeline and possibly below with strong to extreme SW wind on Thursday.

Confidence

Moderate

Avalanche Summary

Thursday morning, several size 2 wind-triggered slabs and loose dry avalanches were observed in Little Yoho on Mt. Stephen and Mount Field. Avalanche control on Mt Bosworth produced one size 2.5 sliding on the deep persistent layer.

Snowpack Summary

10 cm new today with strong to extreme SW - W winds created new wind slabs at all elevations in terrain exposed to the wind. 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

On Friday, we will see cooling temperatures (-14C) and easing winds as arctic air moves in for the weekend. Saturday temperatures will be in the -20C range with sunny skies and light NW wind

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.