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Avalanche Forecast

Archived

Jan 12th, 2019–Jan 13th, 2019

Alpine
Natural and human triggered avalanches likely.
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 possible, human triggered probable.
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

Kootenay Boundary.

A major input of heat into the snowpack can wake up buried weak layers. A lot of uncertainty exists as to what will happen when temperatures climb. Uncertainty is best managed with conservative terrain.

Confidence

Low - Freezing levels are uncertain

Weather Forecast

SATURDAY NIGHT: Mostly cloudy. Light southwest wind. Alpine temps +2 C, temperature inversion with above freezing layer between 1500-2600 m.SUNDAY: Mainly cloudy. Light west-southwest wind with occasional moderate gusts. Alpine temps reaching +4 C, temperature inversion with above freezing layer between 1500-2900 m.MONDAY: Sunny with cloudy periods. Light west wind. Alpine temps reaching +4 C, temperature inversion with above freezing layer between 1500-3000 m.TUESDAY: Sunny with cloudy periods. Light south wind. Alpine temps reaching +2 C, freezing level 2000 m.More details can be found in the Mountain Weather Forecast.

Avalanche Summary

A wind-loaded NW slope was triggered remotely by skiers on Copper Mountain on Friday. The avalanche was reported to have failed on a layer of surface hoar. See the MIN report here. Around the region, several size 1- 2 avalanches had failed naturally within the last 48 hours occuring on steep and unsupported features on north aspects. Solar input Friday afternoon triggered loose wet avalanches on south and east aspects to 2200 m near Kootenay Pass. On Thursday, explosives triggered storm slab avalanches to size 2 and skier traffic triggered size 1-2 storm slabs. Most of these avalanches are reported to have failed within the most recent 20-30 cm storm snow although a few reports suggest some failures on North aspects down 50-60 cm representing accumulated snowfall since December 31. On Wednesday on Mt Kirkup near Red Mountain a backcountry skier was caught in a avalanche, a storm slab is suspected to have been triggered. The same day, natural avalanches to size 2 were reported around the Whitewater area. Explosives triggered storm slab avalanches to size 2 and ski cuts triggered storm slab avalanches to size 1.5.

Snowpack Summary

On Friday, pin wheeling and tree bombs were noted with warming temperatures through the day. Surface snow became moist to 1700 m. At higher elevations, strong southerly winds have redistributed recent storm snow creating variable storm slabs and wind slabs. Wind slabs were observed at all elevations on Monday and may be hidden under the most recent snowfall. Isolated layers of surface hoar and or crusts may be found in the upper snowpack. A weak layer buried early December is down 60-120 cm in the alpine and treeline elevations. It consists of a rain crust, surface hoar, and facets (sugary snow). Professionals are continuing to monitor this interface and although the likelihood of triggering has gone down, if triggered this weak layer has the potential to produce large avalanches. This layer is most likely to be triggered from thin, rocky areas with a variable snowpack or with a large load, like cornice fall.A major input of heat into the snowpack can stress deeper instabilities and buried weak layers may be activated. Use caution as the snowpack responds to the initial punch of rapid warming and spiking freezing levels.

Problems

Loose Wet

Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.

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.