Another warm-up brings rising avalanche risk. Read the new forecasters' blog.
Uncertainty is due to how buried persistent weak layers will react to the upcoming warm weather.
As temperatures rise, large cornice falls are becoming a concern. They can potentially trigger persistent slab avalanches on the slopes below. Carefully manage your exposure to overhead hazards, during the warmest part of the day.
Several weak layers persist in the snowpack. These layers are most likely to be reactive at upper elevations where no surface crust has formed. Surface instabilities or large triggers may step-down to these deeper layers.
Periods of sun will likely trigger avalanches on steep south facing slopes.
On Wednesday, a natural cornice fall pulled a large slab avalanche (size 2.5) on a north alpine slope below.
Continuous wet loose avalanches are being reported (size 1.5 to 2) from steep sunny slopes at all elevations, with some stepping down to deeper instabilities.
Where a thick, supportive surface crust is found, we expect that triggering avalanches on buried weak layers is unlikely.
Variable wind affected snow covers open terrain at upper elevations. A crust is found up to 1800 m and higher on solar slopes. Recent surface hoar up to 10 mm has formed on treeline and alpine features sheltered from the sun and wind.
Three layers of concern currently exist in the upper-mid snowpack. Surface hoar and a crust that formed in mid-March can be found 30 to 70 cm below the snow surface. Below this, another layer of surface hoar that formed in early March can be found at a depth of 60 to 100 cm. Additionally, a layer of facets, surface hoar, and/or a crust from mid-February is buried 120 to 200 cm deep.
The remainder of the snowpack is well consolidated, and there are no current concerns.
Friday Night
Cloudy. 20 to 30 km/h southeast ridgetop wind. Treeline temperature -1 °C. Freezing level 1100 m.
Saturday
Cloudy with 0 to 1 mm/cm of rain/snow. 20 to 40 km/h southeast ridgetop wind. Treeline temperature 0 °C. Freezing level 1300 m.
Sunday
Mostly cloudy with isolated flurries. 30 to 50 km/h south ridgetop wind. Treeline temperature + 3°C. Freezing level 1600 m.
Monday
Cloudy with 5 to 10 cm of wet snow. 20 to 30 km/h south ridgetop wind. Treeline temperature + 2°C. Freezing level 1600 m.
More details can be found in the Mountain Weather Forecast.
