Avalanche Forecast
Issued: Dec 21st, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs and Persistent Slabs.
wlewis,
Avalanche Canada
Keep decision making conservative in the wake of the storm. Storm snow needs time to stabilize and buried weak layers will be sensitive to this new load
Stick to simple and supported terrain
Summary
Confidence
Moderate
Avalanche Summary
On Thursday numerous size 2 wind slabs were reported, naturally and human triggered. We expect widespread natural activity occurred on Friday as the wind and snow continued.
Several slab avalanches up to size 2 have been reported this week on the buried surface hoar layers, primarily on north facing slopes around treeline. These reports include natural and remote human triggers.
Snowpack Summary
30-60 cm of new snow will have fallen by midday Friday, with strong winds creating deeper deposits in north and east facing terrain.
A buried layer of weak surface hoar buried mid-December can be found 35 to 60 cm from the surface. An additional layer of buried surface hoar may exist deeper in the snowpack, roughly 70 to 100 cm below the surface.
The remaining mid and lower snowpack contains several crusts from early in the season that are generally well-bonded to the surrounding snowpack. Snow depth decreases significantly at lower elevations.
Weather Summary
Thursday Night
Cloudy with another 20-30 cm of snow possible, favouring coastal areas as usual. Winds strengthen to 60-80 km/h from the south. Freezing levels sit around 1000 m.
Friday
Cloudy with 10 cm of snow, southerly winds 40-60 km/h, treeline temperature -2 °C. Freezing level 700 m.
Saturday
Cloudy with 1-3 cm of snow, southerly winds increase, 60 km/h. Freezing levels rise over the day to 1500 m treeline temperature -1 °C.
Sunday
Cloudy with light snowfall. Freezing levels rise to 1500 m, and southerly winds strengthen to above 100 km/h.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Approach steep open slopes at and below treeline cautiously, buried surface hoar may exist.
- Storm slabs in motion may step down to deeper layers resulting in large avalanches.
- Don't be too cavalier with decision making, storm slabs may remain sensitive to human triggering.
Problems
Storm Slabs
Storm snow and wind continues to build fresh and reactive slabs.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
Two layers of surface hoar may be found 30 and 90 cm below the snow surface. New snow will increase reactivity of these layers.
Aspects: All aspects.
Elevations: Treeline, Below Treeline.
Likelihood
Expected Size
Valid until: Dec 22nd, 2023 4:00PM
