Flash flooding

Scenes from the Houston area looked like the aftermath of a hurricane in early May 2024 after a series of powerful storms flooded highways and neighborhoods and sent rivers over their banks north of the city. Hundreds of people had to be rescued from homes, rooftops and cars during storms, according to The Associated Press. Huntsville registered nearly 20 inches of rain from April 29 to May 4. More storm systems over the following weeks blew out windows in Houston high rises and caused more flash flooding on urban streets and already saturated ground in the region. Floods are complex events, and they are about more than just heavy rain. Each community has its own unique geography and climate that can exacerbate flooding. On top of those risks, extreme downpours are becoming more common as global temperatures rise. I work with a center at the University of Michigan that helps communities turn climate knowledge into projects that can reduce the harm of future climate disasters. F...

Tropical Storm Hilary made landfall on Mexico’s Baja peninsula, and its damaging wind and heavy rainfall moved into Southern California on Aug. 20, 2023. For the first time ever, the National Hurricane Center had issued a tropical storm watch for large parts of Southern California. Forecasters warned of a “potentially historic amount of rainfall,” and the governors of California and Nevada declared states of emergency. Hurricane scientist Nick Grondin explained ahead of landfall why the storm, with help from El Niño and a heat dome over much of the country, could bring flash flooding, wind damage and mudslides to the region. How rare are tropical storms in the Southwest? California had only one confirmed tropical storm landfall in the past. It was in September 1939 and called the Long Beach Tropical Storm. It caused about US$2 million dollars in damage in the Los Angeles area – that would be about $44 million today. A hurricane in 1858 came close bu...

Powerful storm systems that hit the U.S. Northeast starting July 9, 2023, dumped close to 10 inches of rain on New York’s Lower Hudson Valley in less than a day and sent mountain rivers spilling over their banks and into towns across Vermont. Vermont Gov. Phil Scott said he hadn’t seen rainfall like it since Hurricane Irene devastated the region in 2011. Extreme water disasters like this have disrupted lives in countries around the world in the past few years, from the Alps and Western Europe to Pakistan, India and Australia, along with several U.S. states in 2022 and 2023. The role of climate change is becoming increasingly evident in these types of deluges. Cars were stranded in floodwater on the campus of the United States Military Academy at West Point, N.Y., on July 10, 2023. U.S. Military Academy via AP Studies by scientists around the world show that the water cycle has been inte...

Heavy downpours and a thick snowpack in the Western mountains and Upper Midwest have put communities in several states at risk of flooding this spring – or already under water. Flooding is the costliest type of natural disaster in the U.S., responsible for about 90% of the damage from natural disasters each year. It happens almost every day somewhere in the country. Yet, much of the aging infrastructure meant to protect U.S. communities is in bad shape and, in some cases, failing. The American Society of Civil Engineers gave the nation’s dams, levees and stormwater infrastructure a D grade in its latest report card, in 2021. Help is coming. Congress authorized billions of dollars for infrastructure projects under the Infrastructure Investment and Jobs Act in 2021. But there’s a problem: New infrastructure planning frequently relies on historical flood patterns for its benchmarks rather than forecasts of changing risks as the climate warms. We study flood ris...

The year 2022 will be remembered across the U.S. for its devastating flooding and storms – and also for its extreme heat waves and droughts. The nation saw 18 disasters that caused more than US$1 billion in damage each, well above the average. The year started and ended with widespread severe winter storms from Texas to Maine, affecting tens of million of people and causing significant damages. Then, March set the record for the most reported tornadoes in the month – 233. During a period of five weeks over the summer, five 1,000-year rainfall events occurred in St. Louis, eastern Kentucky, southern Illinois, California’s Death Valley and Dallas, causing devastating and sometimes deadly flash floods. Severe flooding in Mississippi knocked out Jackson’s troubled water supply for weeks. A historic flood in Montana, brought on by heavy rain and melting snow, forced large areas of Yellowstone National Park to be evacuated. In the fall, hurricanes Ian and Fio...