Avalanche Forecast

Archived

Dec 22nd, 2022–Dec 23rd, 2022

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely.

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

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

Temperatures are warming up, but strong West winds will keep things feeling cold on Friday. The incoming storm will all contribute to slab formation on top of our weak snowpack and we are expecting a small natural avalanche cycle at some point in the next few days.

Confidence

Moderate

Avalanche Summary

No avalanches were observed or reported on Thursday.

Snowpack Summary

Overall, the snowpack is shallow and weak with a base of facets and depth hoar. Forecasted snow with warmth and wind will create slabs of varying thickness depending on amount of windloading overtop of this weak base. We expect these to build incrementally starting on Friday as the storm moves in.

Total snowpack depths at treeline range from 60-120 cms.

Weather Summary

A pacific front is approaching bringing wet, warm and windy weather - a much needed reprieve from the frigid temperatures we've been having!

Friday: Low temperatures ~-30 rising to highs near -20 at treeline. Alpine winds will increase to strong from the West. Light snow with amounts up to 5 cm.

Saturday: Low temperatures ~ -20 rising to highs near -10 at treeline. Alpine winds increasing to extreme from the West/ Southwest. Light snow with forecasted amounts ranging from 1-10 cm.

Sunday: Low temperatures ~ -8 rising to -2 at treeline. Freezing level elevation ~ 1500m. Alpine winds decreasing to strong from the West. Light snow with amounts up to 5 cm.

The models vary on total snowfall amounts but anywhere from 5- 25 cm over the period. Models agree on warming temperatures and strong to extreme winds.

Terrain and Travel Advice

Watch for fresh storm slabs building throughout the day.
Uncertainty is best managed through conservative terrain choices at this time.

Problems

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.

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.