Dashboard Regions Weather Stations Radar Alerts Glossary
Contact About
Log In

Register for an account and never miss a forecast again!

Register

Avalanche Forecast

Archived

Dec 16th, 2024–Dec 17th, 2024

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

With winds increasing and new snow on the way, the avalanche hazard is expected to rise by Wednesday.

Recent avalanche reports highlight that the deep persistent problem remains the primary concern; see the avalanche summary for more details.

Confidence

No Rating

Avalanche Summary

On Sunday, we received two separate reports (report 1 / report 2) of large, human-triggered avalanches in the Highway 93N backcountry. Both avalanches failed on the deep persistent avalanche problem. Although recent natural avalanche activity on this layer has been minimal, these reports indicate that it remains active and continues to be the primary concern in the snowpack.

Snowpack Summary

Recent winds have created small wind-slabs in alpine lees. The mid and lower pack is faceted and weak east of the divide, and more settled in western regions. Weak interfaces exist down 20-40 on a facets/suncrust layer, and near the ground on the deep persistent layer (Nov 9 and Oct 20 interfaces). Snowpack depths at tree-line is about 60 cm in eastern areas and 100 cm west of the divide.

Weather Summary

Tuesday: Isolated flurries in the morning, with 2-4 cm of snow accumulation expected throughout the day. Freezing levels will remain at the valley bottom. Ridge winds will increase gradually, reaching moderate to strong values.

Wednesday: Snow intensifying early in the morning, with 10 to 20 cm expected throughout the day. Winds will peak midday, with strong to extreme values from the southwest.

Terrain and Travel Advice

  • Avoid thin areas like rocky outcrops where you're most likely to trigger avalanches on deep weak layers.
  • Watch for newly formed and reactive wind slabs as you transition into wind-affected terrain.

Problems

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.

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.