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Avalanche Forecast

Archived

Dec 19th, 2013–Dec 20th, 2013

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

Regions

Northwest Inland.

Forecasters are working with very little field data at this time. If you are traveling in the backcountry and have information, we'd love to hear about it! [email protected]

Confidence

Poor - Due to the number of field observations

Weather Forecast

Synopsis: Upper NW flow brings significant precipitation to the North Coast over the next few days. This should result in a bit of a snow accompanied by strong winds for the Inland region.Friday: Freezing Level: 700m Precip: 2/4mm 4/8cm Wind: Lht gusting Strong, NW Saturday: Freezing Level: 700m Precip: Trace Wind: Lht gusting Strong, NWSunday: Freezing Level: 1800m Precip: Trace Wind: Mod gusting Extreme, SW

Avalanche Summary

A few small wind slabs just below ridge crest were reported on Dec. 15. No other avalanches have been reported. This likely speaks more to the lack of observations than actual conditions.

Snowpack Summary

We're relying on a shoe string worth of data for this forecast! There is significant variation in snow depths across the region. In the Smithers area the ski hill is reporting an 85 cm base.  Treeline depths vary between 100 - 180 cm.It sounds like a bit of cold dry snow has fallen in the last two days. The weekend storm finished very warm, as a result a crust can be found near the snow surface below 1100m. The best guess is that the last storm produced around 10 - 50 cm of snow. This snow now overlies the layer of  facets/surface hoar that sit above old wind slabs and melt-freeze crusts which were formed during the December cold/dry spell. We don't have great wind stations in the region, but the coast saw a lot of strong wind during the last storm & I suspect this region was similarly hammered by wind. The mid and lower snowpack is still structurally weak due to facets, potentially even depth hoar and an early season crust near the ground.

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.

Deep Persistent Slabs

Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.