Careful terrain choices are needed to manage uncertainty about buried weak layers and the ongoing impact of strong wind.
Strong wind is forecast to shift from northeast to southwest on Friday, which will leave fresh wind slabs on a wide variety of aspects in the alpine and along ridges.
A layer of facets that formed during the arctic outbreak in December is buried 30 to 60 cm deep. This layer produced natural avalanches last week, and recent snowpack observations suggest it could still be reactive to human triggering on steep rocky slopes.
Preliminary reports from Thursday include a large (size 2) wind slab avalanche that occurred on a southwest slope at treeline during a period of strong wind from the northeast.
Over the weekend and last week, there were several reports of larger (up to size 2.5) natural avalanches at all elevations releasing on a 30 to 60 cm deep facet layer. Triggering an avalanche on this weak layer is still possible under the current conditions.
Strong to extreme wind is forming drifts and wind slabs in alpine terrain and along ridges, while sheltered terrain has 10 to 15 cm of low density snow. This snow may sit above a layer of small surface hoar that will sluff easily in steep terrain. A weak layer of facets that formed during the arctic outbreak in December is buried 30 to 60 cm deep. Recent avalanche activity and snowpack tests suggest human-triggering is possible for this layer. We are uncertain about the layer's spatial distribution, but observations suggest it is fairly widespread.
Thursday night
Mostly cloudy, isolated flurries with up to 3 cm of snow, 40 to 50 km/h wind from the southeast, treeline temperatures around -10 °C.
Friday
Cloudy with afternoon flurries brining up to 5 cm of snow, 40 to 60 km/h wind from the southwest, treeline temperatures warm to -5 °C.
SaturdayMix of sun and cloud, no precipitation, 30 to 50 km/h wind from the south, treeline temperatures around -5 °C.
SundayMix of sun and cloud, no precipitation, 30 to 50 km/h wind from the southeast, treeline temperatures around -8 °C.
More details can be found in the Mountain Weather Forecast.
