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Avalanche Forecast

Archived

Feb 16th, 2023–Feb 17th, 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 possible, human triggered probable.
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.

AM UPDATE: More snow fell overnight than expected. Watch for reactive storm slabs at all elevations.

Manage cornices and our complicated snowpack by selecting routes that avoid or limit exposure to large avalanche paths with overhead hazards.

Confidence

Moderate

Avalanche Summary

Several natural, cornice, and human-triggered wind slabs up to size 2 were reported across the region on Wednesday.

A large size 3 avalanche was triggered by a rider in the Esplanades area on the deep persistent weak layer buried in November. Another reminder that this layer is still a player in this region.

Snowpack Summary

Storm totals reach 40 cm in the Monashees and up to 20 cm in the Selkirks. Some wind redistribution of snow isolated to direct lees. New snow will bury a melt-freeze crust that can be found on steep south-facing slopes. Cornices continue to build new overhanging edges with this new snow and winds.

The mid-pack is generally well consolidated with a few operations reporting continued snowpack results on a spotty surface hoar layer down roughly 80 cm. Reports of large avalanches involving various layers of surface hoar/crusts and facets within the mid-pack depth are sporadic but are a reminder of the complicated snowpack across this region.

In the lower snowpack, a layer of large and weak facets from November near the base of the snowpack is slowly gaining strength but there continues to be low confidence in this layer. Large destructive avalanches are the result if this layer is triggered.

Weather Summary

Thursday night

Cloudy with continued flurries tapering Friday morning, 5 to 10 cm accumulations, 10 to 20 km/h

Friday

Mainly cloudy, flurries with 2 to 5 cm accumulation during the day, with a short break before the snow starts again overnight. 15 to 20 km/h southwest winds, treeline temperatures -8 °C.

Saturday

Mainly cloudy, flurries with 5 to 10 cm accumulation, 20 to 30 km/h southwest winds, treeline temperatures -7 °C.

Sunday

Cloudy with flurries, 5 to 10 cm accumulation, 15 to 20 km/h southwest winds, treeline temperatures -6 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Avoid shallow snowpack areas, rock outcroppings and steep convex terrain where triggering is most likely.
  • Recent new snow may be hiding windslabs that were easily visible before the snow fell.
  • Be especially cautious as you transition into wind affected terrain.

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.

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.

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.