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 7th, 2021–Dec 8th, 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 unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
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.

Investigate the bond of new wind slabs to the old surface. In many areas, wind slabs will be sitting on top of a weak layer of facets or surface hoar, making them more reactive to rider triggering. 

Confidence

Moderate - Uncertainty is due to the limited number of field observations. Uncertainty is due to the fact that deep persistent slabs are particularly difficult to forecast.

Weather Forecast

Tuesday Overnight: 2-10cm of new snow accompanied by strong to extreme southwest winds. Freezing levels at valley bottom with alpine temperatures around -10 C. 

Wednesday: A mainly cloudy day with 2-5 cm of new snow, heaviest in the morning. Winds shifting west and easing in the moderate to strong ranges. Alpine temperatures dropping to around -15 C. 

Thursday: A quieter day with a brief ridge of high pressure developing in northern BC. Partially cloudy with flurries. Accumulation up to 3cm. Moderate to strong NW winds. 

Friday: A strong frontal system will move over the region, bringing strong to extreme SW winds, freezing levels rising to 1000m, and up to 15cm of new snow. Heaviest in the afternoon and increasing into the evening. 

Avalanche Summary

On Saturday, a size 3 avalanche was reported in the Hankin-Evelyn area, failing near the ground. This has us thinking about the potential for a deep persistent weak layer.

If you do head out in the backcountry, please share your observations to the Mountain Information Network!

Snowpack Summary

2-10 cm of new snow overnight will be redistributed into wind slabs in the alpine and treeline by strong to extreme southwest winds. Prior to the new snow, cold and clear nights have promoted faceting and surface hoar growth on the snow surface. This will create a touchy sliding layer for new wind slabs, especially where it overlies a crust.

Exposed areas may be stripped back to the Dec 1 Crust. This crust has been reported up to 1600m in the south end of the region. 

An early season crust can be found near the base of the snowpack. It has shown reactivity in the past week with large loads (explosives' and cornice), creating large avalanches. We don't know how widespread this problem may be, but with incoming snow and wind we are definitely keeping an eye on it, and would be avoiding large features and areas with thin to thick snowpack transitions. 

Snowpack depth at treeline ranges from 100-250 cm, alpine depths average 200-300 cm.

Terrain and Travel

  • Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
  • If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
  • Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.

Problems

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.

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.