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Avalanche Forecast

Archived

Dec 25th, 2018–Dec 26th, 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.

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

Confidence

High -

Weather Forecast

TUESDAY NIGHT: Cloudy with light snowfall, freezing level below valley bottom.WEDNESDAY: Cloudy with light snowfall, accumulation 5 cm, moderate southwest winds, alpine temperature -9 C, freezing level below valley bottom.THURSDAY: Mix of sun and cloud, light northwest winds, alpine temperature -7 C, freezing level below valley bottom.FRIDAY: Increasing clouds over the day, light to moderate southwest winds, alpine temperature -6 C, freezing level below valley bottom.

Avalanche Summary

No avalanches were observed in the region on Monday. 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

Wind slabs may linger in lee terrain features at high elevations. Otherwise, reports suggest that the recent snow is bonding well to the snowpack. Below around 1800 m, expect recent storm snow to sit on a melt-freeze crust. Although limited reports are available, recent MIN posts suggest that the snow is bonding relatively well to the crust.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. There has not been reports of avalanche activity on this layer for 5 days. Although this layer is likely gaining strength, field observations show that slab avalanches remain possible on this layer where it exists. 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. A very large trigger, such as a cornice fall, would likely be needed to form an avalanche on this layer.

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.