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 31st, 2020–Jan 1st, 2021

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

Regions

Northwest Inland.

A storm will impact the region, bringing snow and strong wind. Slabs may form rapidly over the day and load buried weak layers. Conservative terrain travel is recommended.

Confidence

Moderate - Forecast precipitation (either snow or rain) amounts are uncertain.

Weather Forecast

THURSDAY NIGHT: Cloudy with snowfall, accumulation 5 to 15 cm, 40 km/h southwest wind, alpine temperature -6 C.

FRIDAY: Cloudy with snowfall, accumulation 5 to 15 cm, 40 southwest wind, alpine temperature -5 C, freezing level rising to 1000 m.

SATURDAY: Cloudy with snowfall, accumulation 5 to 10 cm, 60 km/h southwest wind, alpine temperature -8 C.

SUNDAY: Cloudy with snowfall, accumulation 5 to 10 cm, 60 km/h southwest wind, alpine temperature -9 C.

Avalanche Summary

A small but hard wind slab avalanche was remotely triggered by a rider on Wednesday, occurring on a west aspect around 1700 m from reverse loading.

Avalanche activity may spike during the incoming storm, once sufficient snow loads the buried weak layers described in the snowpack summary. Avalanches could be triggered naturally or by riders and the result may be very destructive.

Snowpack Summary

A storm is forecast to drop upwards of 30 cm of snow by Friday afternoon. Storm and wind slabs may form rapidly during the storm and they may overly a weak and feathery surface hoar layer, particularly in sheltered treeline and below treeline terrain.

Around 50 to 100 cm deep, a hard melt-freeze crust from early December may have weak and sugary faceted grains around it. The last reported avalanche activity on this layer was December 17 and 19. The likelihood of triggering this layer may increase during the storm.

The early-November melt-freeze crust may be found near the base of the snowpack and have weak faceted grains around it. The last reported avalanche activity was near Smithers on December 22. The most likely terrain to trigger it would be in shallow and rocky alpine areas.

Terrain and Travel

  • Watch for fresh storm slabs building throughout the day.
  • Be careful with wind loaded pockets, especially near ridge crests and roll-overs.
  • Storm slabs in motion may step down to deeper layers resulting in large avalanches.
  • In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.

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.

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.

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.