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 will become a concern. They can potentially trigger persistent slabs on the slopes below. Carefully manage your exposure to overhead hazards, during the warmest part of the day.
Weak layers of surface hoar and facets in the upper snowpack have recently produced large avalanches. 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 Monday, a few wet loose avalanches were seen from steep terrain features. Where a thick, supportive surface crust is found, we expect that triggering avalanches on buried weak layers is unlikely.
Evidence from last week's natural avalanche cycle continued to be reported with very large slab avalanches (to size 4) failing on buried persistent weak layers.
A melt-freeze crust has formed on most surfaces. Dry snow persists on northerly aspects at upper elevations.
Three persistent weak layers remain notable in the snowpack and have been responsible for recent large avalanches. Surface hoar that formed in mid-March can be found 50 to 100 cm below the snow surface. Below this, another layer of surface hoar that formed in early March can be found at a depth of 100 to 150 cm. Additionally, a layer of facets, surface hoar, and/or a crust from mid-February is buried 100 to 200 cm deep.
Friday Night
Cloudy. 20 to 30 km/h southeast ridgetop wind. Treeline temperature 0 °C. Freezing level 1200 m.
Saturday
Cloudy with 0 to 1 mm/cm of rain/snow. 20 to 40 km/h southeast ridgetop wind. Treeline temperature 1 °C. Freezing level 1500 m.
Sunday
Mix of sun and cloud. 40 to 60 km/h south ridgetop wind. Treeline temperature +4 °C. Freezing level 2000 m.
Monday
Mostly cloudy with 5 to 10 cm of new snow. 30 to 40 km/h southwest ridgetop wind. Treeline temperature 0 °C. Freezing level 1400 m.
More details can be found in the Mountain Weather Forecast.
