Avalanche Forecast
Issued: Dec 22nd, 2019 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs and Persistent Slabs.
mconlan,
Avalanche Canada
The storm has quieted but avalanche conditions remain very dangerous. The recent snow will remain touchy and it is resting on a few weak layers. Read more about this concern here. Avoid alpine avalanche terrain and conservative decision-making is essential at and below treeline.
Summary
Confidence
Moderate - Uncertainty is due to how quickly the snowpack will recover and gain strength.
Weather Forecast
SUNDAY NIGHT: Mostly cloudy with isolated flurries, accumulation 1 to 3 cm, light southwest wind, alpine temperature -3 C, freezing level 1400 m.
MONDAY: Cloudy with light snowfall, accumulation 2 to 5 cm, light southwest wind, alpine temperature -5 C, freezing level 1200 m.
TUESDAY: Mostly cloudy with isolated flurries, accumulation 1 to 3 cm, light southwest wind, alpine temperature -8 C, freezing level below valley bottom.
WEDNESDAY: Mix of sun and cloud, light north wind, alpine temperature -9 C, freezing level below valley bottom.
Avalanche Summary
A widespread avalanche cycle occurred on Saturday and potentially continued into Sunday. Many of the avalanches released within the storm snow, producing large avalanches on all aspects and generally above 2000 m. One avalanche was triggered by explosives on the late-November layer described in the Snowpack Summary. It is likely that more occurred on this layer as well, but were not observed due to limited visibility.
Snowpack Summary
The storm is calming down but has deposited around 60 to 90 cm of snow in the region, with strong west wind. This snow has loaded multiple weak layers, including:
- a feathery surface hoar layer buried around 60 to 100 cm.
- a surface hoar layer buried about 80 to 120 cm, with an associated melt-freeze crust on steep south aspects.
- a complex layer of weak and sugary faceted snow, surface hoar, and melt-freeze crusts in the bottom half of the snowpack buried late November.
There is uncertainty on which of these layers will remain a problem after the storm. However, given the weak nature of these layers, it is prudent to expect that they could still produce large and destructive avalanches.Â
Terrain and Travel
- Travel in alpine terrain is not recommended.
- Don't let the desire for deep powder pull you into high consequence terrain.
- Continue to make conservative terrain choices while the storm snow settles and stabilizes.
Problems
Storm Slabs
Snowfall totals will reach around 60 to 90 cm across the region from the weekend's storm. The snow (and rain at lower elevations) fell with strong west wind, forming touchy slabs that have produced large and destructive avalanches. Storm slabs are expected to remain reactive to skier traffic on Monday.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
Three different weak layers may be found in the snowpack. It is uncertain whether the rapid loading from the storm cleaned them out and hence whether they will remain a concern in the distant future. Until more evidence exists, it is prudent to assume the layers are present and capable of forming very large, destructive avalanches. Best to avoid alpine terrain until the uncertainty about these layers decreases.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Dec 23rd, 2019 5:00PM
