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Avalanche Forecast

Archived

Jan 31st, 2023–Feb 1st, 2023

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.
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.

A skier-triggered deep persistent slab in the Birkenhead area on Friday suggests that a deeply buried weak layer is still in play. Avoid large steep slopes, especially where the snowpack depth is variable. Also watch for pockets of wind slabs in atypical areas.

Confidence

Moderate

Avalanche Summary

Reports from the past few days are limited to one small wind slab avalanche (size 1.5) from Sunday. It occurred naturally on a reverse-loaded feature in the Hurley area. On Friday, a size 2.5 skier-triggered deep persistent slab occurred in the Birkenhead area. This avalanche was remotely triggered, meaning the skier was a distance away from the slab when it occurred (100 m above). It occurred on a wind-loaded slope in the alpine during a period of strong solar radiation. The crown was 150 cm deep.

Please continue to share any observations or photos on the Mountain Information Network.

Snowpack Summary

Northerly winds have affected open areas in the alpine and treeline, scouring windward slopes and creating pockets of wind slabs in lee areas. In sheltered areas, 10 to 20 cm of recent storm snow is faceting with cold temperatures. A surface crust can be found below 1800 m and all elevations steep solar aspects.

In the midpack, a weak layer can be found 50 to 100 cm deep, as a decomposing crust, or in many places, it's more of a soft and weak section of the snowpack. There is a widespread weak layer of facets and depth hoar at the bottom of the snowpack.

Generally, the snowpack in this region is weak and shallow. Snowpack depths around treeline are highly variable and range between 150 to 250 cm.

Weather Summary

Tuesday night

Cloudy with light flurries bringing trace amounts of snow, 30 to 40 km/h southwest wind, treeline temperatures around -10 ˚C.

Wednesday

Mostly cloudy, isolated flurries with trace amounts of snow, 30 to 40 km/h southwest wind, treeline temperatures warm to -7 ˚C.

Thursday

Mix of sun and cloud, no precipitation, 30 to 50 km/h south wind, treeline temperatures warm to -5 ˚C.

Friday

Cloudy with scattered flurries bringing 1 to 5 cm of new snow, 40 to 60 km/h south wind, treeline temperatures warm to -3 ˚C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Watch for wind-loaded pockets especially around ridgecrest and in extreme terrain.
  • Wind slabs may be poorly bonded to the underlying crust.
  • Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
  • Be mindful that deep instabilities are still present and have produced recent large avalanches.

Problems

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.

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.