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 18th, 2020–Dec 19th, 2020

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

Regions

Northwest Inland.

New snow and wind will mean that storm slabs are to be expected, and will likely be reactive to human triggering, especially in wind loaded areas.

Confidence

Moderate - Uncertainty is due to the limited number of field observations.

Weather Forecast

FRIDAY NIGHT - Flurries, 5-15 cm / west wind, 50-80 km/h / alpine low temperature near -8

SATURDAY - Flurries, 5-15 cm / southwest wind, 40-80 km/h / alpine high temperature near -4 

SUNDAY - Sunny with cloudy periods and isolated flurries / southwest wind, 30-60 km/h / alpine high temperature near -6 

MONDAY - Mainly sunny / light winds / alpine high temperature near -7 

Avalanche Summary

There were a few natural avalanches up to size 2 reported on Thursday. Check out this great MIN report from Hankin that outlines a few avalanche observations.

A wind slab avalanche likely stepped down to the facets described in the snowpack summary, producing a large avalanche near Smithers earlier this week. 

Please consider sharing your observations to the Mountain Information Network Thank you to those that have already submitted this winter!

Snowpack Summary

20-40 cm of recent fresh snow and strong southwest wind has likely formed reactive storm slabs. This new snow likely sits on a melt-freeze crust from early December, which may have weak and sugary faceted grains growing around it.

 

A crust that was buried in early November is near the base of the snowpack. This crust has weak facets associated with it. These facets have produced large avalanches in both the south and north of the region within the past week.

Snowpack depths vary substantially with aspect, elevation, and wind exposure. 

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.
  • If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
  • Avoid shallow, rocky areas where the snowpack transitions from thick to thin.

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.