The famed Pineapple Express touted by skiers in the Western U.S. may not be all it’s cracked up to be. Instead of bringing fresh powder, the the atmospheric river storms, as they’re technically known, more often bring snow-destroying rain to many areas.
A new study by NASA and several other research institutions took a close look at data from satellites and ground observations from 1998 through 2014 to show the connection between atmospheric river storms and rain-on-snow events. According to the study, the atmospheric rivers are two-and-a-half times more likely than other types of winter storms to result in destructive “rain-on-snow” events, which increase flood risks in winter and reduce water availability the following summer.
Atmospheric rivers are narrow streams of very humid air that flow thousands of miles from the warm subtropical Pacific Ocean to the West Coast of North America. When the warm, moist air flows up and over the Sierra Nevada and other mountain ranges it condenses to form precipitation.