Flash flooding

Rivers of muddy water from heavy rainfall raced through city streets as thousands of people evacuated homes downhill from California’s wildfire burn scars amid atmospheric river storms drenching the state in early January 2023. The evacuations at one point included all of Montecito, home to around 8,000 people – and the site of the state’s deadliest mudslide on record exactly five years earlier. Wildfire burn scars are particularly risky because wildfires strip away vegetation and make the soil hydrophobic – meaning it is less able to absorb water. A downpour on these vulnerable landscapes can quickly erode the ground, and fast-moving water can carry the debris, rocks and mud with it. After the 2018 mudslide in Montecito, firefighters checked homes. Twenty-three people died in the disaster. Wally Skalij/Los Angeles Times via Getty Images With more storms expected through mid...

The summer of 2022 started with a historic flood in Montana, brought on by heavy rain and melting snow, that tore up roads and caused large areas of Yellowstone National Park to be evacuated. It ended with a record-breaking heat wave in California and much of the West that pushed the power grid to the breaking point, causing blackouts, followed by a tropical storm that set rainfall records in southern California. A typhoon flooded coastal Alaska, and a hurricane hit Puerto Rico with more than 30 inches of rain. In between, wildfires raged through California, Arizona and New Mexico on the background of a megadrought in Southwestern U.S. that has been more severe than anything the region has experienced in at least 1,200 years. Near Albuquerque, New Mexico, a five-mile stretch of the Rio Grande ran dry for the first time in 40 years. Persistent heat waves lingered over many parts of the country, setting temperature records. At the same time, during a period of five weeks between...