New snow at higher elevations could form fresh slabs. If triggered, they could step down to deeper weak layers.
Continue to make conservative terrain choices.
Multiple persistent weak layers in the snowpack have been stressed and are primed for human triggering, including remotely from flat terrain.
New snow at higher elevations could form fresh slabs. If triggered, they could step down to deeper weak layers.
Expect strong solar radiation to trigger small wet loose avalanches.
Keep in mind that small avalanches in motion may step-down to deeper weak layers.
A significant avalanche cycle swept through the Columbia Mountains from Monday to Thursday, producing many full-path, size 3 and 4 avalanches. These included persistent slab, storm slab, wet slab, wet loose, and cornice failures.
While natural avalanche activity is expected to decrease, the snowpack remains unstable and untrustworthy after enduring extreme stress from rapidly rising freezing levels and snow/rain.
Convective flurries Friday night may deposit 10 to 25 cm of dry snow at upper elevations, but accumulations will be highly variable. This snow will fall on a wet, rain-soaked upper snowpack. Expect a frozen crust to form across most terrain, except possibly on north alpine slopes.
Recent avalanche activity has involved multiple persistent weak layers. The most common failure layer is the early March surface hoar, facet, and crust layer, buried 70 to 150 cm deep. Many avalanches have also stepped down to deeper weak layers from February and January, buried 150 to 200 cm deep. These layers are still adjusting to recent stress and remain a serious concern for human-triggering and step-down avalanches.
Friday Night
Cloudy with 10 to 25 cm of snow above 1100 m, rain below. 10 to 20 km/h west ridgetop wind. Treeline temperature -3 °C. Freezing level 1400 m.
Saturday
Mix of sun and cloud with 0 to 10 cm of snow above 1500 m, rain below. 10 to 20 km/h west ridgetop wind. Treeline temperature -1 °C. Freezing level 1900 m.
Sunday
Sunny. 10 to 20 km/h southeast ridgetop wind. Treeline temperature 0 °C. Freezing level 2000 m.
Monday
Mostly cloudy. 10 to 20 km/h southeast ridgetop wind. Treeline temperature -2 °C. Freezing level 1800 m.
More details can be found in the Mountain Weather Forecast.
