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Avalanche Forecast

Archived

Feb 13th, 2023–Feb 14th, 2023

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

Regions

North Columbia, South Columbia, Esplanade, Jordan, North Selkirk, Shuswap, Badshot-Battle, Central Selkirk, Goat, Gold, Kokanee, North Okanagan, Retallack, Valhalla, Whatshan.

Recent snow will take some time to stabilize, avoid steep, open terrain and back off if you see evidence of nearby avalanches, or if you notice cracks appear in the snow surface or other signs of instability.

Confidence

Moderate

Avalanche Summary

Natural and human triggered wind slabs and storm slabs continue throughout the region. Avalanche activity last week on the deep persistent weak layer continues to remind us that these layers are taking time to heal and continue to require diligence.

Going forward storm and wind slabs developed with the most recent new snow and moderate to strong winds will take some time to bond to previous surfaces. Triggering these layers in the upper snow pack could step down to weak layers deeper in the snowpack.

Snowpack Summary

10 to 30 cm of new snow accumulated in the region over the past few days with the highest amounts in the north of the region. This new snow has been redistributed by moderate to strong southwest winds at upper elevations building wind slabs in lee features in open alpine and treeline terrain.

These new wind slabs will be forming over previous surfaces of soft snow in sheltered terrain and old wind slabs in open terrain and continue to build over a melt-freeze crust that extends up to 1800 m in the northern part of the region and up to 2000 m further south. Small facets may be found above the crust. This layer warrants close monitoring as we move through the period where a critical load and slab properties may develop over it.

Deeper in the snowpack two layers of surface hoar which formed in early January are now roughly 80 to 140 cm deep. Although snowpack tests are indicating strengthening here, these weak layers are still being watched closely by local operators and may be associated with recent isolated step-down avalanches.

Large and weak facets from November are near the base of the snowpack and although avalanche activity on this basal weakness has been on a bit of a decline, it still figures prominently in the assessments and terrain use (and avoidance) of professionals throughout the region.

Weather Summary

Monday night

Cloudy with easing but convective flurries, 2 to 5 cm of new snow, 5 to 10 km/h northwest winds, treeline temperatures around -10 °C.

Tuesday

A mix of sun and cloud with isolated flurries, 5 to 10 km/h west winds, treeline temperatures around -11 °C.

Wednesday

Mainly cloudy, 5 to 10 km/h southwest winds, trace accumulations, treeline temperatures -7 °C.

Thursday

Mainly cloudy, flurries 5 to 10 cm of accumualtion, 20 to 30 km/h winds, treeline temperatures -8 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Use careful route-finding and stick to moderate slope angles with low consequences.
  • Storm slabs in motion may step down to deeper layers resulting in large avalanches.
  • Avoid shallow snowpack areas, rock outcroppings and steep convex terrain where triggering is most likely.

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.

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.

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.