A new study by NASA, Scripps Institution of Oceanography at UC San Diego, and other partners has found that in California’s Sierra Nevada, atmospheric river storms are two-and-a-half times more likely than other types of winter storms to result in destructive “rain-on-snow” events, where rain falls on existing snowpack, causing it to melt. Those events increase flood risks in winter and reduce water availability the following summer.

The study, based on NASA satellite and ground-based data from 1998 through 2014, is the first to establish a climatological connection between atmospheric river storms and rain-on-snow events.