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Avalanche Forecast

Archived

Feb 10th, 2015–Feb 11th, 2015

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.
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.

What will all the forecast warming do to the snowpack? I'm honestly not sure. With this much uncertainty sticking to conservative terrain may be the only reasonable course of action.

Confidence

Poor - Due to the number of field observations

Weather Forecast

The big story for the next few days is the freezing level which should be on the rise throughout the period. Wednesday: Freezing level around 1800m, no precipitation, Light variable winds at all elevations. Thursday: Freezing level starts near 1800m, rising to around 2500m by the afternoon. Winds light at treeline, strong west at upper elevations. No precipitation. Friday: Freezing should be hovering around 3000m all day. Light winds at treeline, moderate SW winds at ridgetop. No precipitation.

Avalanche Summary

Observations have been essentially non-existent in recent days. This likely speaks more to a lack of observers rather than actual conditions. I'm confident recent storm loading has produced large storm slab avalanches at higher elevations, while loose wet or wet slab avalanche activity occurred at lower elevations where rain fell.

Snowpack Summary

Since February 5th, moderate to heavy precipitation fell throughout the region. The rain line during the storms generally hovered around 1700m, although there were periods where rain fell into the alpine. In the alpine, heavy accumulations of moist, dense snow have been pushed by strong southwest winds into much deeper deposits in upper elevation lee terrain. The recent storm snow overlies a hard crust layer (which may have overlying surface hoar) which was formed in late January. At lower elevations, continuous rain has saturated the snowpack. I suspect cornices are large and fragile.In the mid to lower snowpack, you may find the mid-December crust/facet/surface hoar combo. At lower elevations rain has likely destroyed what was left of this layer. At higher elevations recent storm loading may have produced very large avalanches at this interface, although observations have been extremely limited.

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.

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.