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Avalanche Forecast

Archived

Jan 3rd, 2018–Jan 4th, 2018

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

Regions

North Columbia.

Tricky conditions warrant a conservative approach. A little warming, precipitation and/or wind-loading could be all we need to awaken a volatile persistent slab, especially at treeline.

Confidence

Moderate - Freezing levels are uncertain

Weather Forecast

Thursday: Mix of sun and cloud, with flurries possible in the valleys. A layer of warm air is expected between 2000-2500m, while it remains cold in the valleys. Light variable winds.Friday: Cloudy with flurries. Moderate southwesterly winds.Saturday: Light snow (5-10 cm). Light to moderate south-westerly winds.More details can be found in the Mountain Weather Forecast.

Avalanche Summary

There have been a several recent reports of remote-triggered (triggered from a distance) and naturally triggered persistent slab avalanches to size 2 on all aspects between 1400-2300m. Several loose dry and a few solar-triggered loose wet avalanches have also been reported. Reactivity of the persistent slab is likely to increase with warmer temperatures as the upper snow becomes denser.

Snowpack Summary

Warming is starting to turn dry powder into a cohesive slab in some areas. The main troublemaker in the snowpack at the moment is a layer of feathery surface hoar down 50-70 cm, buried in mid-December. In places this interface exists as a crust/facet combo. It is most prevalent around treeline, but it may be more widespread in some locations. A little more warming, precipitation and/or wind-loading could be all that is needed to turn powder into an easy-to-trigger slab above this touchy interface. It's tricky to predict and even professionals are scratching their heads a bit about exactly when and where this beast will wake up. It's a good time for conservative decision-making.Deeper in the snowpack (about 80-120 cm down), a rain crust from November remains in the back of our minds, but it is considered dormant for now. If you have any recent observations, please share them through the Mountain Information Network.

Problems

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 Dry

Loose Dry avalanches are the release of dry unconsolidated snow and typically occur within layers of soft snow near the surface of the snowpack. These avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs.