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Avalanche Forecast

Archived

Dec 16th, 2022–Dec 17th, 2022

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, 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, Birkenhead, Duffey, South Chilcotin, Stein, Taseko.

Danger ratings have decreased but concern still remains for deeper weak layers and lingering wind loaded features. Maintain your awareness as you travel.

Deep persistent slab problem are uncommon in the region. Good travel habits and conservative terrain choices are tools to manage this problem.

Confidence

Moderate

Avalanche Summary

As northerly winds are expected to continue to redistribute snow, rider triggered wind slabs remain possible.

On Monday near Pemberton, a skier-triggered persistent slab avalanche occurred on a northwest aspect in the alpine. The bed surface of this avalanche was reported as a crust with large surface hoar above. Interestingly, this avalanche triggered a size 2 on a nearby slope, which failed on facets and depth hoar near the ground level. Settlements (a sign of instability) have been reported in shallow and rocky features where weak layers sit shallower and closer to the surface.

If you head out into the mountains, please share your photos or observations on the Mountain Information Network. Your information helps us understand local conditions!

Snowpack Summary

In exposed terrain at higher elevations, pockets of wind slab sit in wind loaded features. Strong winds have pushed this snow into features lower on slopes than typically seen. Large surface hoar has been reported on the surface in sheltered areas, with a crust present on solar aspects.

A layer of weak surface hoar sits buried around 20-40 cm deep. The upper snowpack is generally low density and weak. The mid and lower snowpack consist of crusts and facet layers, with depth hoar observed near the ground, which is very weak and highly uncommon for this region. These layers are the primary concern for this area.

The snowpack is currently weak and shallow for mid December. In deeper areas, snowpack depths only reach 100-130 cm.

Weather Summary

Friday Night

Increasing cloud. With light to moderate northwest winds. Freezing level below valley bottom.

Saturday

Mostly cloudy with 2 cm of snow possible. Moderate westerly winds continue. Freezing level below valley bottom. Alpine high of -10 °C.

Sunday

Around 5 cm of snow possible overnight. A mostly cloudy with a trace to 3 cm of snow possible. Light and variable winds. Temperatures drop further, with alpine highs of -20°C.

Monday

Mostly cloudy with moderate southwest winds. Freezing level below valley bottom. Alpine high of -20 °C. Isolated flurries possible.

Sunday

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Avoid freshly wind loaded terrain features.
  • Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
  • If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
  • The best and safest riding will be on slopes that have soft snow without any slab properties.

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.

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.