As rain decreases on the East Coast, the threat of flooding increases.
The heaviest rain from a widespread storm that drenched the eastern United States appeared to have ended across much of the Mid-Atlantic and Northeast on Wednesday morning, but meteorologists said the risk of flooding was just beginning.
“The worst time for flooding is right after the rain stops,” said Patrick Wilson, a meteorologist at the National Weather Service office in Blacksburg, Virginia, in a region of the state where heavy rain closed roads on Tuesday. “It takes time for all the water to drain.”
After the storm wrenched moisture from the Gulf of Mexico, rain began to trickle down mountains into creeks and accumulate in tributaries and streams, from where it can eventually overflow rivers, he said.
Flood warnings, which indicated that flooding was imminent or reported along a river, were in effect early Wednesday for millions of people in much of Virginia and parts of Connecticut, Delaware, Massachusetts, New Jersey, New York, Pennsylvania, West Virginia, North Carolina and other parts of Virginia. parts of several other southern states, according to the National Weather Service.
Many of these warnings were expected to last until late Wednesday morning, but forecasters said flooding could continue through Thursday.
Coastal flood warnings were also in effect in major cities along the East Coast, including Baltimore, New York, Philadelphia and Washington.
Officials echoed meteorologists’ warnings. New York Governor Kathy Hochul said Tuesday evening that she was concerned about the threat of flooding in her state, especially in the Hudson Valley, where a rainstorm had killed one person last summer.
In Annapolis, Maryland, where parts of the downtown area were underwater Tuesday evening, emergency officials said the flood was expected to increase by another foot around 3 a.m. Wednesday. Authorities in nearby Baltimore issued a similar warning.
In the Appalachians, the storm dumped more than two inches of rain on Tuesday, prompting flood warnings across central Virginia, said Mr. Wilson of the National Weather Service. By Wednesday morning, roads near creeks, streams and low-lying areas were flooded. He said he expected the swell to reach population centers such as the city of South Boston within hours.
Mr Wilson said residents should take care when driving. “The biggest risk of danger during floods is driving on flooded roads,” he said. “That’s why you hear: ‘Turn around, don’t drown.’”
Threats to America’s aging flood infrastructure are increasing due to climate change. Researchers say climate change is intensifying rainstorms: warmer air can hold more moisture. So storms are expected to produce more rain than local pipes and culverts can handle.