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Avalanche Forecast

Archived

Dec 23rd, 2018–Dec 24th, 2018

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

Regions

South Coast Inland.

Wind slabs may linger at higher elevations. For the north of the region, be diligent around treeline, where a buried weak layer still lingers. See the forecaster's blog, which describes this persistent problem: www.avalanche.ca/blogs/persistent-slab

Confidence

Moderate - Due to the number of field observations.

Weather Forecast

SUNDAY NIGHT: Mostly cloudy, freezing level 1000 m. MONDAY: Clearing over the day, light south winds, alpine temperature -8°c, freezing level 900 m. TUESDAY: A mix of sun and cloud, light northwest winds, alpine temperature -9°c, freezing level below valley bottom. WEDNESDAY: Mostly cloudy, light southwest winds, alpine temperature -9°c, freezing level below valley bottom.

Avalanche Summary

No avalanches were observed in the region on Saturday. The last large cycle was on Thursday in the north of the region, with large avalanches up to size 3. These avalanches ran within the storm snow as well as on the weak layer described in the snowpack summary.

Snowpack Summary

Around 10 cm of snow fell in the region on Sunday with associated strong winds, likely forming small wind slabs in the immediate lees of ridges. Below around 1800 m, expect the storm snow to sit on melt-freeze crust formed by rain from Thursday's storm. In the north portion of the region and possibly the far south, a weak layer of facets and surface hoar lies below all this storm snow, around 100 to 150 cm deep. The weak layer appears most prominent around treeline, up to 2000 m. While the layer is likely gaining strength, field observations show that slab avalanches remain possible on this layer where it exists. See this MIN post for snowpack test results around the Duffey on this layer. Near the base of the snowpack, a crust exists with weak and sugary facets beneath it. This could potentially still be of concern in high north-facing aspects where the snowpack rests on very smooth ground cover.

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.

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.