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 23rd, 2020–Dec 24th, 2020

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

South Coast Inland.

The alpine is unseasonably warm, which may make slabs easy to trigger.

Confidence

Moderate - Uncertainty is due to how the snowpack will react to the forecast weather.

Weather Forecast

WEDNESDAY NIGHT: Clear skies, 20 to 40 km/h southwest wind, alpine temperature -1 C, above-freezing layer around 2000 m in the south of the region.

THURSDAY: Clear skies, 30 to 50 km/h southwest wind, alpine temperature 0 C, above-freezing layer dissipating by the end of the day in the south of the region.

FRIDAY: Increasing clouds, 20 km/h south wind, alpine temperature -1 C.

SATURDAY: Cloudy with snowfall, accumulation 5 cm, 20 km/h south wind, alpine temperature -5 C.

Avalanche Summary

We received reports of the recent storm snow forming reactive slabs on Wednesday at treeline and alpine terrain.

A few persistent slab avalanches were triggered in the north of the region in the past few days, near the Hurley. They were triggered by riders, heavy machinery, and naturally. The slabs were generally 60 to 90 cm deep, around 2000 m, and released on the weak layers described in the snowpack summary.

Snowpack Summary

Around 60 cm of snow fell near Coquihalla and Manning Park on Monday and 15 cm accumulated near Duffey Lake. Since then, strong wind from variable directions has formed wind slabs in exposed terrain up high. Warm air is forecast for the alpine and particularly for the south of the region, which could mean that these slabs may remain easy to trigger.

A hard melt-freeze crust from early December is found around 40 to 120 cm deep in the snowpack. This crust may have weak layers above it, consisting of feathery surface hoar or sugary faceted grains. These weak layers do not appear to be prevalent in the south of the region but may be found in the north (e.g., Duffey Lake, Hurley). The snowpack should be treated as suspect anywhere you find either surface hoar or faceted grains above the crust.

The remainder of the snowpack is well-settled in the south of the region. In the north, another melt-freeze crust with associated faceted grains around it may be found near the ground. Without evidence of recent avalanche activity, the layer appears to be dormant at this time.

Terrain and Travel

  • Avoid steep slopes when air temperatures are warm, or solar radiation is strong.
  • Be careful as you transition into wind affected terrain.
  • Give the new snow several days to settle and stabilize before pushing into bigger terrain.
  • 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.

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.