What is an atmospheric river? With millions of people under flood alerts, a hydrologist explains the good and bad of these storms and how they’re changing
- Written by Qian Cao, Hydrologist, Center for Western Weather and Water Extremes, University of California, San Diego

Millions of people were under flood alerts and winter storm warnings on Jan. 31 and Feb. 1, 2024, as a series of atmospheric rivers brought heavy downpours and the threat of flooding, mudslides and avalanches to the Pacific Northwest and...