Warm air and solar input are mainly driving the danger. The likelihood of triggering cornices and loose wet avalanches will increase over the day and there is uncertainty as to whether deeper weak layers could reactivate during this diurnal cycle period.
Cornices are large and looming along many ridgelines. Cornices may weaken during daytime heating, increasing the likelihood of being naturally triggered or failing from the weight of a human.
Persistent weak layers that were buried in January and February could reactivate during this relatively warm period. Assess for these layers and look for clues of instability.
Warm temperature and periods of sunshine will increase the likelihood of triggering wet loose avalanches, particularly on solar aspects.
SATURDAY NIGHT: Clear skies, 20 to 30 km/h south wind, alpine temperature 0 C, freezing level 2300 m but cooling at lower elevations.
SUNDAY: Sunny with increasing afternoon cloud, 20 to 30 km/h south wind, alpine temperature 0 C, freezing level 2200 m.
MONDAY: Mix of sun and cloud, 10 km/h northeast wind, alpine temperature 0 C, freezing level 2100 m.
TUESDAY: Mix of sun and cloud, 10 km/h northwest wind, alpine temperature 0 C, freezing level 2100 m.
Small wind slabs were triggered naturally and by skiers on Friday out of steep northerly alpine terrain.
A relatively high freezing level and sunny periods may weaken the snowpack in the coming days and increase the likelihood of loose wet avalanches, cornice failures, and perhaps a reactivation of deeper weak layers.
We are in the midst of a melt-freeze cycle, with freezing levels heightening above 2000 m. The snow surface is expected to freeze during the night and heat up during the day, particularly on southerly aspects during sunny periods. Dry snow may still be found at high elevations on north aspects. An overall weakening trend of cornices is expected during this diurnal cycle.
Deeper in the snowpack, a persistent weak layer from late January is buried around 80 to 150 cm and is composed of a combination of surface hoar, facets, and crusts. There is uncertainty about whether this problem will reactive during this diurnal cycle, but it remains possible.
As always, best to avoid shallow, rocky areas where a weak and faceted snowpack may be found.
