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Avalanche Forecast

Archived

Dec 20th, 2020–Dec 21st, 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.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely.
Treeline
Natural avalanches unlikely.
Below Treeline
Natural avalanches unlikely.

Regions

South Coast.

A surface crust is likely found up to treeline elevations, with possible wind slabs above. Monday's snow may slide easily on the crust, but only 5 cm is forecast.

Confidence

Moderate - Forecast precipitation (either snow or rain) amounts are uncertain.

Weather Forecast

SUNDAY NIGHT: Partly cloudy, 20 to 40 km/h west wind, treeline temperature -1 C, freezing level 1000 m.

MONDAY: Snow, accumulation 5 cm, 20 km/h east wind, treeline temperature -3 C, freezing level 600 m.

TUESDAY: Clear skies, 10 km/h north wind, treeline temperature -2 C, freezing level 700 m.

WEDNESDAY: Partly cloudy, 10 km/h northwest wind, treeline temperature -1 C, freezing level 800 m.

Avalanche Summary

The surface melt-freeze crust has capped the snowpack and limited avalanche activity where it exists. Any new snow that falls onto this crust is expected to slide easily until the snow bonds to it, which could take a few days. Should you venture to the highest mountain tops in the region, you may come across wind slabs formed on the weekend that could still be triggerable.

Snowpack Summary

Around 5 cm of snow is forecast for Monday, which will fall onto a hard melt-freeze crust up to around 1500 to 1700 m. This snow is expected to slide easily on the crust, but the consequence will be low. Above around 1500 to 1700 m, the weekend's precipitation may have all fallen as snow and formed wind slabs that could still be triggered by riders.

There are numerous other melt-freeze crusts buried in the snowpack, but no recent avalanches or concerning snowpack test results have been observed around them.

Terrain and Travel

  • Watch for areas of hard wind slab on alpine features.
  • Closely monitor how the new snow is bonding to the crust.
  • When a thick, melt-freeze surface crust is present, avalanche activity is unlikely.
  • Cornices often break further back than expected; give them a wide berth when traveling on ridgetops.

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.