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Avalanche Forecast

Archived

Nov 27th, 2019–Nov 28th, 2019

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

North Columbia.

Clear, cold, and dry weather is forecast for Thursday. The potential to trigger wind slabs lingers in the alpine.

Confidence

Low - Uncertainty is due to the limited number of field observations.

Weather Forecast

Wednesday night: Mostly clear skies, alpine temperatures -18 C, strong east/northeast winds, no significant precipitation expected.

Thursday: Mostly sunny, alpine temperature -15 C, light easterly wind, no precipitation.

Friday: Mostly sunny, alpine temperature -10 C, light easterly wind, no precipitation.

Saturday: Mostly sunny, alpine temperature -8 C, light variable wind, no precipitation.

Avalanche Summary

Observations are limited this time of year, so there is a fair bit of uncertainty about the extent of current avalanche activity. This small, skier-triggered avalanche was reported Monday following the weekend storm. The most likely place to trigger avalanches right now is where the wind previously drifted snow into wind slabs. If you see anything while out in the field, please consider sharing that information with us and the backcountry community via the Mountain Information Network.

Snowpack Summary

Snow line sits around 1200 m, and snow depths range from 90-140 cm at treeline elevations.

With this week's clear, cold, and dry weather, the weekend storm snow is likely losing strength, except where it has been drifted into wind slabs in the alpine. Variable winds have redistributed the 20-30 cm of recent snow into wind slabs that may still be possible to trigger. In some areas, this snow sits on a crust with surface hoar (feathery crystals). This "Nov. 23 crust" has produced repeatable sudden or propagating results in snowpack tests.  

A variety of crusts from late October are buried deeper in the snowpack (down 60 to 100 cm). The inactive weather pattern this week also promotes a decreasing trend in reactivity for these layers.

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.