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

Nov 25th, 2024–Nov 26th, 2024

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

Regions

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

It's all about the wind right now, or lack of it. The past week has been almost calm, and the surface snow is deep and fluffy. This will change when the wind begins to blow: windslabs will form and the danger will rise. Watch closely for this tipping point, but until then enjoy the good conditions and avoid steep NE-NW facing alpine slopes.

Confidence

Moderate

Avalanche Summary

Besides some minor sluffing in the new snow, only one size 1.5-deep persistent slab avalanche, triggered by an explosive, was reported at the LL ski area on Monday. On Saturday (>48 hrs ago), a skier went for a ride in a deep persistent slab avalanche at Bow Summit: size 2, ~50m wide x ~150m long, failed on the Oct crust (ground). This was previously reported as a size 1 but has been upgraded.

Snowpack Summary

10-20 cm of low-density storm snow sits over an early-season snowpack ranging from 50-90 cm deep at treeline. Two weak layers exist: a Nov 9 crust layer 25-40 cm above the ground, and an Oct crust just above the ground with facets and depth hoar developing around the Oct crust. We have limited observations of how widespread this Oct layer is, but it seems to be most prominent at treeline and above on northerly aspects.

Weather Summary

The cool and calm weather should continue for another day, as we are under the influence of a NW flow that brings cold temps, light flurries and mostly light winds. The lack of wind has been the dominant feature of the weather over the past week and we keep expecting it to change, but it hasn't yet. Tuesday will range from -5 to -15 with treeline winds light from the NW an no new snow.

Terrain and Travel Advice

  • Be aware of the possibility for full depth avalanches due to deeply buried weak layers.
  • Pay attention to the wind; once it starts to blow, sensitive wind slabs are likely to form.
  • Be careful with sluffing in steep terrain, especially above cliffs and terrain traps.

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.