Avalanche Forecast
Issued: Feb 1st, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs and Persistent Slabs.
astclair,
Avalanche Canada
While refrozen surfaces at lower elevations pose little avalanche hazard, large avalanches may be triggered in areas with deep or drifted snow at higher elevations. Be prepared to assess conditions and adjust your travel as you gain elevation.
Summary
Confidence
Weather Forecast
Saturday night: Mostly cloudy, isolated convective flurries with up to 5 cm of accumulation, moderate west winds, alpine temperature -12 C.
Sunday: Increasing cloud, isolated convective flurries with up to 10 cm of accumulation, moderate southwest winds, alpine high temperature around -8 C.
Monday: Mostly clear, light northwest winds, alpine high temperature -9 C.
Tuesday: Mostly cloudy, 5-10 cm of snow, moderate southwest winds, alpine high temperature --9 C.
Avalanche Summary
Throughout the storm, there have been reports of large (size 2-3) natural avalanches releasing in the new snow. Most of these have been storm and wind slab avalanches, on all aspects, at all elevations. They have been triggered by humans, explosives, and naturally. Cornices may also be reaching their breaking point and may act as triggers for these avalanches. Below tree line, small wet loose avalanches were releasing naturally on Saturday up to 1800 m.
With continuous stormy weather over the past week, operators have reported three persistent slab avalanches that were both naturally and skier-remote triggered. These very large (size 2.5-4) avalanches were breaking 100-200 cm deep across a variety of aspects above 1900 m. Easier-to-trigger storm slab avalanches or cornice fall may have the potential to step-down to this layer.
Snowpack Summary
30-60 cm of storm snow has accumulated at upper elevations (generally above 1800 m). Higher snow totals fell in the southeastern parts of the region. Moderate south winds with strong gusts have drifted the snow into deeper, stiffer slabs in wind-exposed areas and have rapidly loaded cornices. During a warming event Saturday night, rain saturated snow surfaces up to around 1800 m that have since refrozen with cooling temperatures.
The mid and lower snowpack are generally well settled and strong, however there is a weak layer of surface hoar currently buried 70 to 130 cm deep. This layer has recently shown signs of instability in the region. New snow, rain, and warming have added considerable strain to this weak layer, and it may require more time to adjust to the recent load.
Terrain and Travel
- Storm snow and wind is forming touchy slabs. Use caution in lee areas in the alpine and treeline.
- Continue to make conservative terrain choices while the storm snow settles and stabilizes.
- If triggered, storm slabs in-motion may step down to deeper layers and result in very large avalanches.
Problems
Storm Slabs
Ongoing snowfall and wind will continue to build touchy storm slabs at treeline and alpine elevations. Expect this problem to be more pronounced in wind-drifted areas with deeper, stiffer slabs.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
The combination of rapid snowfall, strong winds, and fluctuating temperatures have added considerable strain to a deeper weak layer buried in the snowpack. Easier-to-trigger storm slab avalanches or large cornice triggers could step down to this persistent slab problem resulting in a very large avalanches.
Aspects: All aspects.
Elevations: Treeline, Below Treeline.
Likelihood
Expected Size
Valid until: Feb 2nd, 2020 5:00PM
