Avalanche Forecast
Issued: Jan 5th, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Persistent Slabs.
mconlan,
Avalanche Canada
Recent strong wind has formed wind slabs. Don't discount the multiple buried weak layers in the snowpack.
Summary
Confidence
High -
Weather Forecast
SUNDAY NIGHT: Partly cloudy with isolated flurries, local amounts 2 to 5 cm, moderate northwest wind, alpine temperature -10 C, freezing level below valley bottom.
MONDAY: Mix of sun and cloud with afternoon snowfall, accumulation 2 to 10 cm, light to moderate west wind, alpine temperature -8 C, freezing level 500 m.
TUESDAY: Cloudy with snowfall, accumulation 15 to 25 cm, moderate to strong southwest wind, alpine temperature -3 C, freezing level 1100 m.
WEDNESDAY: Morning snowfall and afternoon clearing, accumulation 10 to 15 cm, light northwest wind, alpine temperature -6 C, freezing level 1000 m.
Avalanche Summary
Numerous small to large storm and wind slab avalanches were triggered naturally, by humans, and by explosives on Saturday. They were generally on northwest to northeast aspects and at treeline and alpine elevations. The slabs were most commonly 10 to 20 cm thick.
Snowpack Summary
Around 40 to 60 cm of recent storm snow has been redistributed by strong westerly wind, forming wind slabs in lee terrain features. The slabs may overly a thin layer of ice formed early January.
There are multiple weak layers buried in the snowpack. A weak layer of feathery surface hoar is buried around 30 to 50 cm. Around 80 to 120 cm deep, two more surface hoar layers may be found. Near the bottom of the snowpack, weak faceted snow may be found. This fundamentally unstable snowpack structure remains a concern, as it is capable of producing large and destructive avalanches. It is possible that wind slab avalanches could step down to these deeper layers or the layers could be triggered in areas where the snowpack is relatively thin.
Terrain and Travel
- Make conservative terrain choices and avoid overhead hazard.
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
- Be aware of the potential for large avalanches due to the presence of buried surface hoar.
Problems
Wind Slabs
Recent strong westerly wind has formed wind slabs in exposed terrain features. Use particular caution near ridges, where wind slabs may be touchy to human traffic.
Aspects: North, North East, East, South East, South.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
Several persistent weak layers are buried in the snowpack. Although these layers become harder to trigger as they get deeper, the destructive potential of a triggered avalanche increases. These layers could be triggered by humans where the snowpack is relatively thin or a wind slab avalanche could step down to them.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Jan 6th, 2020 5:00PM
