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Avalanche Forecast

Archived

Feb 17th, 2017–Feb 18th, 2017

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

Regions

South Columbia.

The best riding right now is probably on high north aspects, which is also where the hazard is the highest. Don't let your guard down when searching for fresh powder.

Confidence

Moderate - Forecast snowfall amounts are uncertain

Weather Forecast

SATURDAY: Cloudy with flurries bringing another 5-10 cm overnight, light winds and freezing levels around 1300 m.SUNDAY: Cloudy with light flurries, light southerly winds and freezing levels around 1400 m.MONDAY: Cloudy with light flurries bringing another 5-10 cm, moderate southwesterly wind and freezing level around 1400 m.

Avalanche Summary

Reports from Thursday and Friday morning include natural, ski-cut and explosives controlled 15-40 cm thick storm and wind slab avalanches up to Size 2.5. Other reports include continued natural wet avalanche activity up to Size 2.5 at lower elevations below the rain line. A MIN report from Sunday describes a remotely triggered size 3 avalanche on London Ridge. Click here for more details. Touchy new storm slabs are sensitive to light triggers and have the potential to step down and trigger persistent slab avalanches.

Snowpack Summary

Expect to find 25-40 cm of fresh snow bonding poorly to buried surface hoar and/or a crust, and blown into touchy wind slabs at higher elevations. At lower elevations the snow surface is wet and cohesionless and should soon freeze into a solid crust. Rapidly settling storm snow from last week is still bonding poorly to the previous snow surface from early February, which is now down 60-80 cm and includes a sun crust on steep sun-exposed slopes, faceted snow, as well as surface hoar on sheltered open slopes. The mid and lower snowpack are generally well settled and stable in deeper snowpack areas but may be faceted and weaker in shallower areas.

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.