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

Regions

South Coast.

Storm slabs are expected to form overnight and they may be particularly reactive to human traffic on Saturday. A conservative mindset will be important to manage this problem.

Confidence

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

Weather Forecast

FRIDAY NIGHT: Cloudy with snowfall, accumulation 10 to 15 cm, strong west wind, treeline temperature -2 C, freezing level 900 m.

SATURDAY: Mix of sun and cloud, moderate northwest wind, treeline temperature -2 C, freezing level 1000 m.

SUNDAY: Cloudy with snowfall, accumulation 15 to 20 cm, strong southwest wind, treeline temperature -2 C, freezing level 1000 m.

MONDAY: Mix of sun and cloud, light to moderate northwest wind, treeline temperature -5 C, freezing level 500 m.

Avalanche Summary

No new avalanches were observed on Thursday. Avalanche activity is expected to increase during and after Friday night's storm. 

Snowpack Summary

Around 10 to 15 cm of snow is expected Friday night. The snow will fall onto a weak layer of surface hoar, which was reported to be 10 to 15 mm in size and on all aspects and elevations. The surface hoar overlies a breakable melt-freeze crust, meaning that the surface hoar will likely act as an easy sliding layer for the storm snow. The snow will also fall with strong westerly wind, so the deepest deposits will be in lee terrain features.

The remainder of the snowpack is well-settled.

The snowpack depth varies from around 200 to 250 cm at the peaks of the North Shore mountains (1400 m) and rapidly decreases with elevation to no snow below 1000 m.

Terrain and Travel

  • Be aware of the potential for larger than expected storm slabs due to the presence of buried surface hoar.
  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • 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.