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Avalanche Forecast

Archived

Dec 19th, 2013–Dec 20th, 2013

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

Regions

Kootenay Boundary.

Confidence

Fair

Weather Forecast

Friday: Cloudy with light to moderate snowfall – around 5 cm. The freezing level is at valley bottom and ridgetop winds are moderate but gusty from the west-northwest. Saturday: Mainly cloudy with a chance of flurries and sunny breaks. The freezing level could jump to 700 m and moderate gusty northwest winds continue. Sunday: Possible sunny breaks and flurries. The freezing level could climb to 1200 m and the upper flow continues to be northwesterly.

Avalanche Summary

No avalanches have been reported in the last few days.

Snowpack Summary

It's been an exceptionally dry December so far. The total monthly precipitation in Nelson is 40 mm, and 30 mm of that fell in one storm at the beginning of the month. Hopefully the weather pattern changes soon!Recent light snowfall and strong westerly winds formed pockets of soft wind slab on lee slopes and scoured windward slopes in exposed terrain. Between 35 and 50cm below the surface you may find a weak layer of surface hoar on sheltered slopes or a melt-freeze crust on steep solar aspects. Most reports indicate this layer is "stubborn" to trigger, or there may not be a deep enough overlying slab to create a significant hazard. That said, I'd remain curious about this interface, especially as the snow load above gradually increases.In general, snowpack depths are below seasonal average and many slopes below treeline are reported to be below threshold for avalanche activity. Deeper snow is likely in the northern part of the region.

Problems

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind 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.