Triggering a persistent slab can lead to serious consequences.
It's critical to stay disciplined and choose only well-supported, low-consequence lines.
Moderate to gusty winds will likely form wind slabs in localized open terrain and near ridge tops. Watch for newly formed and reactive small slabs as you transition into wind-affected terrain. Slabs in motion may step down to deeper weak layers, resulting in large avalanches.
The mid-December widespread weak layer is now down 50 to 75 cm. Numerous and continued remote-triggered avalanches were reported to have failed on this layer since Wednesday. Other weak layers are also found deeper within the top 1.5 m of the snowpack. Use extra caution where the snowpack varies from thick to thin, near rock outcrops and convexities. Larger-than-expected avalanches are possible due to the presence of a deeper weak layer.
Few natural and human-triggered storm and wind slabs (up to size 2) were reported Friday in Revelstoke area. They have released on thin convex rolls and /or steep unsupported slopes around treeline.
Since Wednesday, continuous occurrences of very large natural and human-triggered persistent slabs (size 2 to 3) failing on the mid-December weak layer. Some were remotely triggered. Few stepped down to deeper buried weak layers. Many of these human-triggered avalanches were a surprise to the individuals triggering them.
Please continue to share any observations or photos on the Mountain Information Network.
Between 20-25 cm of light snow is now overlying the recent dense storm snow. New snow has been redistributed to northerly aspects at higher elevations and fresh soft slabs may not bond well to previous surfaces.
The mid-December widespread weak layer of sugary faceted grains and/or small surface hoar is found down 50-75 cm. This layer was responsible for numerous large natural and human-triggered avalanches since Dec 27. At lower elevations, a significant rain crust can be found down 40-50 cm.
In the mid-snowpack, up to three weak layers created earlier in December can be found. Some of these may not exist in all areas of our region. The November weak layer can be found anywhere between 100 and 150 cm down. The very large avalanches reported since Dec 27 step down into these deeper weak layers.
The bottom of the snowpack is generally weak and faceted.
Periods of snow will persist overnight as the coastal system weakens. Greater amounts are expected in the western sections. An upper ridge will be bringing widespread subsidence late Sunday and fair weather for the weekdays.
Saturday night
Light snow up to 5 cm except up to 10 cm over the Monashees and Cariboos, southerly ridge winds up to 40 km/h, treeline temperatures -5 °C. Freezing level around 500 m.
Sunday
Cloudy, lingering flurries, northwesterly ridge winds up to 25 km/h, treeline temperatures -4 °C. Freezing level around 750 m.
Monday
Mainly sunny, no precipitation, southwesterly ridge winds at 20 km/, treeline temperatures around -8 °C. Freezing level at valley bottom.
Tuesday
Mainly sunny, no precipitation, southwesterly ridge winds at 20 km/, treeline temperatures around -10 °C.
More details can be found in the Mountain Weather Forecast.
