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Avalanche Forecast

Archived

Jan 18th, 2024–Jan 19th, 2024

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

Regions

Banff Yoho Kootenay, Little Yoho, Banff, East Side 93N, Kootenay, Lake Louise, LLSA, Sunshine, West Side 93N, Field.

Forecasted ridgetop winds will become moderate to strong from the SW on Friday. Watch for fresh wind-slabs in the alpine and exposed tree-line locations.

Confidence

No Rating

Avalanche Summary

A road patrol on Highway 93 North in good visibility showed one size 1 wind slab on the east face of Mt Saskatchewan. Sunshine Village reported two natural wind-slabs (size 2) above Bourgeau Left and Right waterfalls. The slab on Bourgeau Right came over the waterfall.

The ski-hills reported several explosive triggered wind-slabs in the alpine.

Snowpack Summary

10-20 cm recent storm snow and increased winds on Friday will create fresh wind-slabs at treeline and above. 30-50 cm overlies the Dec. 31 surface hoar/sun crust. Below this, in the mid-pack, two crusts (Dec. 22 and Dec. 5) exist as high as 2350m and have been providing the primary support for skiing. The base of the snowpack remains weak with depth hoar and facets.

Weather Summary

Friday will bring increasing cloudiness with light snow in the afternoon. Ridgetop winds will be from the SW and increase through the day to mod-strong. Valley bottom temperatures will rise to -13.

Saturday will bring scattered flurries and mod to strong SW winds. Valley bottom temperatures will rise to around -8.

For more information, click here for the Mountain Weather Forecast.

Terrain and Travel Advice

  • 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.

Loose Dry

Loose Dry avalanches are the release of dry unconsolidated snow and typically occur within layers of soft snow near the surface of the snowpack. These avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs.

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.