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 5th, 2023–Dec 6th, 2023

Alpine
Natural and human triggered avalanches likely.
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.
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 is happening with heavy wet storm snow overlaying a generally weak faceted snowpack. Skiers should be choosing conservative terrain. Ice-climbers should be picking routes with no over-head hazard.

Confidence

Moderate

Avalanche Summary

Numerous natural avalanches up to size 2 were reported on Tuesday running as storm slabs and deep persistent slabs at all elevations. Widespread whumphing and cracking was reported in areas not steep enough to avalanche.

Snowpack Summary

Up to 35 cm of moist storm snow overlays well developed surface hoar, faceted snow, and sun-crusts on steep south aspects. Previous strong SW winds have formed windslabs in alpine and tree-line locations. The mid and lower pack is generally weak and faceted. Snow depths range from 40-60 cm at tree-line and up to 90 cm in deeper alpine locations.

Weather Summary

A continued SW flow will bring more snow to the forecast area on Wednesday with another 20 cm possible by the evening. Freezing levels will hover around 1300m then lower to valley bottom on Thursday. Winds should taper through the day on Wednesday and switch from SW to W.

For more information click Mountain Weather Forecast.

Terrain and Travel Advice

  • Storm slabs in motion may step down to deeper layers resulting in large avalanches.
  • Avoid exposure to overhead avalanche terrain, avalanches may run surprisingly far.

Problems

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.