Happy New Year! Have a safe start to this new year by avoiding wind-loaded areas and practicing good travel habits. Recently formed wind slabs overlie a slick crust and are expected to remain reactive to human triggering.
A low-probability but high-consequence deep persistent slab problem should have you avoiding thin rocky areas and exposure to overhead hazards. Learn more about how to manage this problem in the avalanche summary...
Recent snowfall was accompanied by strong southwesterly winds, creating deep deposits of wind slab in lee terrain features. Wind slabs may remain reactive to human triggering, especially where they overlie a slick rain crust formed early last week.
Keep in mind that if triggered, wind slabs may step down to deeper layers resulting in very large avalanches.
A crust with weak, faceted snow above and below exists near the base of the snowpack. Human-triggering this layer is unlikely, but large loads such as cornice fall or a smaller avalanche stepping down to this layer are possible. Avoid thin, rocky, wind-affected areas were triggering this layer is most likely.
On Friday, numerous natural and human-triggered storm slabs were reported up to size 2. These slabs mainly occurred in wind-loaded terrain and failed on the underlying rain crust.
Several large (size 2 to 2.5) slab avalanches were produced during explosive control work on Thursday. All in alpine terrain on a variety of aspects. A number of avalanches slid on deep persistent weak layers, with crowns of 1.5 to 2 m deep.
The weak facet/crust interface near the base of the snowpack has begun to show reactivity to large loads in the past week. This layer now presents a low-probability but high-consequence problem that is atypical for our coastal snowpack. Learn more about the nature of this deep persistent slab problem from this forecaster blog.
Please continue to post your observations and photos to the Mountain Information Network.
This week, 20-60 cm of storm snow was accompanied by strong southwest winds, creating hard wind-affected surfaces in open areas and wind slabs in lee terrain features. This new snow overlies a rain crust formed earlier in the week. This crust is thin at higher elevations and up 2 cm thick below treeline.
The mid-snowpack consists of moist snow at lower elevations and a series of crusts and denser snow at upper elevations.
Near the base of the snowpack, a weak facet/crust layer can be found.
Total snow depths are roughly 100 to 200 cm at treeline.
Saturday night
Clear periods. Alpine temperatures drop to a low of -6 °C. Mostly light southwesterly ridge wind occasionally gusting to 30 km/h. Freezing level at valley bottom.
Sunday
A mix of sun and cloud. Alpine temperatures reach a high of -3 °C. Ridge wind light to 20 km/h from the southwest. Freezing level rises to 700 metres.
MondayA mix of sun and cloud. Alpine temperatures reach a high of -2 °C. Mostly light southerly ridge wind occasionally gusting to 40 km/h. Freezing level rises to 900 metres.
TuesdayCloudy with sunny periods and isolated flurries. Alpine temperatures reach a high of -4 °C. 20km/h gusting to 50 km/h southerly winds at ridgetop. Freezing level rises to 800 metres.
More details can be found in the Mountain Weather Forecast.
