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

Feb 9th, 2023–Feb 10th, 2023

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 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.

An avalanche cycle continues, evidenced by today's avalanche control results and observations of natural avalanches, We expect this current peak in avalanche danger to last for a few days while the snowpack adjusts. Human triggering is likely in avalanche starting zones.

Confidence

High

Avalanche Summary

Very touchy windslabs found Thursday during avalanche control on HWY 93 S. Some avalanches released when the bag hit the slope before the explosive detonated. Field teams observed widespread activity up to size 3 on the Icefields Parkway yesterday with propagations up to 300 meters and around the sunshine area Thursday to size 2. Avalanche control on Sunshine road Wednesday and on Hwy 93 S Thursday produced results up to size 3. Many avalanches stepped to the ground, especially in terrain that has not previously avalanched.

Snowpack Summary

Regional snowfall totals since Feb 1: Bow Summit 43 cm, Bosworth 37 cm, Sunshine 34 cm, Simpson 31 cm, Stanley 22 cm.

Strong winds have moved this new snow into widespread, reactive windslabs at higher elevations, confirmed by avalanche control on Wednesday & Thursday. Two crusts are buried within the upper snowpack and the November facets remain near the base. These buried weak layers are now producing avalanches, including a wake-up of the November facets. Minimal reactivity has been observed below treeline.

Weather Summary

Another system crosses the region Friday with 2-4 cm of snow, moderate-strong SW winds and alpine temperatures in the -2 to -10 range.

Saturday, expect isolated flurries with minimal accumulations. Winds will be in the 30-40 km/h range.

Sunday valley bottom temperatures reach +2C before dropping to cooler temperatures with the passage of a cold front bringing 5-10 cm and strong winds for areas along the Divide and West.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Make conservative terrain choices and avoid overhead hazard.
  • If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.

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.