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Avalanche Forecast

Archived

Dec 4th, 2019–Dec 5th, 2019

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

Regions

Kootenay Boundary.

Human triggered avalanches remain likely in parts of the region that received more than 20 cm of snow in the recent storm.

Confidence

Moderate - Uncertainty is due to how quickly the snowpack will recover and gain strength.

Weather Forecast

WEDNESDAY NIGHT: Clearing skies overnight, light wind from the northwest, alpine temperatures drop to -8 C.

THURSDAY: Increasing cloud throughout the day, 30 km/h wind from the southwest, alpine high temperatures around -2 C.

FRIDAY: Scattered flurries bring 5-10 cm of new snow, 30-50 km/h wind from the southwest, alpine high temperatures around -1 C.

SATURDAY: Flurries continue with another 5-10 cm of snow, 40 km/h wind from the southwest, alpine high temperatures around -1 C.

Avalanche Summary

New snow and wind has formed fresh slabs that will be most reactive in wind affected terrain. Several small (size 1) human triggered slab avalanches were reported on Tuesday and Wednesday. These slabs were between 10 to 30 cm thick and occurred on all aspects.

Snowpack Summary

The past few days delivered about 15-30 cm of snow to most parts of the region, with the exception of the Kootenay Pass area that received closer to 40 cm of snow. This snow has been blown around by southwest wind and sits above hard layers of wind pressed snow and crusts. These hard layers could provide a bed surface for avalanches to slide on. The lower snowpack contains several 'sandwiched' layers of facets and crusts as well as a potential surface hoar layer (see video here). These type of layers can potentially develop into avalanche problems, but recent observations suggest they are unreactive at the moment. Snowpack depths are about 120 cm at treeline and taper quickly below treeline.

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.