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

Feb 21st, 2020–Feb 22nd, 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 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

South Coast Inland.

Friday night's storm will drop snow onto various surfaces that the snow may not bond well to. Conservative decision making is recommended. The danger may be one step lower in the south of the region (e.g. Coquihalla, Manning), where less snowfall is forecast.

Confidence

Moderate - Forecast snowfall amounts are uncertain.

Weather Forecast

FRIDAY NIGHT: Cloudy with snowfall, accumulation 10 to 15 cm in the north of the region and 5 cm in the south, moderate to strong west wind, alpine temperature -6 C, freezing level 1000 m.

SATURDAY: Mix of sun and cloud, light to moderate northwest wind, alpine temperature -8 C, freezing level 1000 m.

SUNDAY: Cloudy with snowfall, accumulation 5 cm, moderate southwest wind, alpine temperature -7 C, freezing level 800 m.

MONDAY: Morning snowfall and afternoon clearing, accumulation 5 cm, light to moderate west wind, alpine temperature -10 C, freezing level 700 m.

Avalanche Summary

No new avalanches were observed on Thursday. Avalanche activity is expected to increase Friday night into Saturday with the new snow, particularly in the north of the region.

Snowpack Summary

Around 5 to 15 cm of snow is expected to fall Friday night, with the most in the north of the region. The snow will fall onto a melt-freeze crust on solar aspects or a weak layer of surface hoar, which was reported to be 4 to 8 mm in size in sheltered terrain. In the north of the region, the surface hoar sits on about 10 to 15 cm of weak and sugary near-surface facets. Friday night's snow will also fall with strong westerly wind, so the deepest deposits will be in lee terrain features.

The midpack is well-settled.

In the north part of the region (e.g. Duffey/Hurley/Goldbridge), a deep instability exist in the snowpack, consisting of a weak basal facet-crust complex. Sporadic avalanche activity on this layer is keeping it on our radar, with the latest report described here. In the south of the region, including the Coquihalla and Manning areas, there are no concerns about deeply buried weak layers.

Terrain and Travel

  • Be aware of the potential for large avalanches due to the presence of buried surface hoar.
  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • If triggered, storm slabs in-motion may step down to deeper layers and result in very large avalanches.
  • Choose conservative terrain and watch for clues of instability.

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.