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 12th, 2020–Dec 13th, 2020

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

Regions

Northwest Inland.

  

There have been reports of large explosive triggered avalanches failing on sugary facets near the ground during this past week. Cornice falls or smaller avalanches in motion may have the potential to step-down to these deeper layers, producing large, destructive avalanches.

Confidence

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

Weather Forecast

  

SATURDAY NIGHT: Partly cloudy / Light, southeast ridgetop wind / Alpine low temperature -17/ Freezing level valley bottom.

SUNDAY: Cloudy / Light, southwest ridgetop wind / Alpine high temperature -13 / Freezing level valley bottom.

MONDAY: Mostly cloudy. / Moderate, southwest ridgetop wind / Alpine high temperature -12 / Freezing level valley bottom.

TUESDAY: Cloudy with flurries; 3-5 cm. / Strong, southwest ridgetop wind / Alpine high temperature -10 / Freezing level valley bottom.

Avalanche Summary

There have been a couple reports of large(size 3) explosive triggered avalanches failing on sugary facets near the ground in the north of this region near Tatlatui provincial park during this past week. These have been triggered by both explosives and heavy snow loading during the last storm. 

Data in this region is very sparse. Please submit your observations to the Mountain Information Network. 

Snowpack Summary

Recent winds from a variety of directions have reverse loaded some slopes, creating wind slabs on typically windward features at treeline and above. 

Up to 20 cm of recent snow fell at upper elevations and may sit above a newly formed crust. This new snow may have a poor bond to the underlying crust and be reactive to human triggering. 

In many treeline and below treeline areas, the combination of above freezing temperatures and rain saturated the entire snowpack. As a result, the snow has melted fast at lower elevations, and snowpack depths have seen rapid settlement. 

At the base of the snowpack sits the early November crust with weak, sugary facets below. These facets near the bottom of the snowpack have produced very large deep persistent slab avalanches near the Ningunsaw and Tatlatui Provincial Parks. Although the extent of this snowpack structure in the region is not well-known, it may be more prevalent in northern half of the region. 

Snowpack depths vary substantially with aspect, elevation, and wind exposure. Below treeline the terrain may still be below the threshold for avalanches. 

Terrain and Travel

  • Recent wind has varied in direction so watch for wind slabs on all aspects.
  • 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 lee and cross-loaded terrain.
  • Avoid shallow, rocky areas where the snowpack transitions from thick to thin.

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.

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.