Large-scale slushflow event in West Greenland - magnitude, triggers and drivers

Climate models project a strong increase in Arctic precipitation with rain becoming the dominant form, as well as an advanced start of the snow melting period in the coming century. This will heavily impact the Cryosphere and likely the frequency and magnitude of slushflow and wet snow activity, commonly occurring in the Arctic. Slushflows are a type of wet snow avalanche releasing from a strength loss within oversaturated snowpacks caused by rain-on-snow events and rapid spring snow melting. Wet snow avalanches in general are highly destructive due to their potential in entraining an entire, high-density snowpack as well as surface sediments, transporting these masses over large distances. On 11 April 2016 we observed high slushflow and wet snow avalanche activity at the environmental monitoring station Kobbefjord (KF) in W-Greenland. Here we show that the avalanches released as a result of snow wetting induced by rain-on-snow in combination with a large air temperature rise. The causing synoptic weather situation influenced large parts of W-Greenland which lead to the largest-scale avalanche event recorded, with more than 800 slushflows and wet snow avalanches detected using spaceborne radar remote sensing.