Millions Brace for Potentially Serious Rain and Flooding Coming to Mid-Atlantic, Northeast

Several states have been experiencing rain on and off for days—and it doesn't look as if it's going to let up anytime soon. Forecasts up and down the East Coast show the familiar rain and thunderbolt symbols every day for the next week, with a few exceptions in some areas.

"We've had a very unusual flow that's come out of the tropical region," Ross Dickman, a meteorologist in charge of the National Weather Service in New York, told Newsweek on Tuesday. A high-pressure system responsible for the flow was expected to break down, allowing the severe weather to cross over into New York City and Long Island on Wednesday, he said.

"That will bring the potential for some heavy rain and possible flooding," Dickman told Newsweek. While on Tuesday morning, the area only had a hazardous weather outlook, the National Weather Service was considering issuing a flood watch for Wednesday, he said.

As of Tuesday morning, pockets of heavy fell over North Carolina and had spread north through Virginia, Maryland, Pennsylvania and New York state. The rain prompted the National Weather Service to issue a mix of flood watches and warnings up and down the coast, as well as hazardous weather outlooks for areas that could expect rain.

"Multiple rounds of showers and thunderstorms will continue to stream across the Carolinas and into the Northeast—with some of these storms producing heavy rain," the short-range forecast from the National Weather Service said Tuesday.

In Pennsylvania, Hersheypark and Knoebels Amusement Resort were both closed Monday due to extreme flooding. ZooAmerica was also closed Monday and was set to remain closed through Tuesday.

Flooding in central Pennsylvania was expected to continue onTuesday.

"The flash flood threat today is significant for much of Central PA. Some small streams and creeks are flooding too. Please, please, please heed all flood warnings and don't drive or walk through flood waters," Jeff Jumper, a meteorologist with the Pennsylvania Emergency Management Agency, tweeted.

Some of the heaviest rainfall was expected to fall across Pennsylvania, New York, Connecticut and New Jersey. A map from the National Weather Service showed that expected rain totals could reach six inches in some areas.

A stubborn upper trough and wealth of tropical moisture will continue to impact the East with heavy rain and flash flooding through mid-week. The left graphic shows how much precipitation fell over the last 48hrs and the right graphic shows the forecast through Thurs evening.

— National Weather Service (@NWS) July 23, 2018

Some areas in the Hudson Valley, northeastern New Jersey and the southern Connecticut interior could experience some of the worst of the storms. There, rains and thunderstorms could repeatedly pass over the same areas, but elsewhere the rain wasn't expected to fall continuously for days on end, Dickman said.

Those along the East Coast should be prepared to monitor forecasts and should pay attention to any watches or warnings issued by their local National Weather Service office. Any time a flood warning, whether it's a flash flood or regular flood warning, is issued, those in the area should be ready to flee to higher ground. A warning means a flash flood or flood is imminent or already occurring in the area. These can be hazardous and sometimes incredibly dangerous, so people should have plans to evacuate.

Flood watches and flood advisories are different from outright warnings: A flood watch means there are conditions that could possibly produce a flood, but it doesn't necessarily mean a flood will happen. A flood advisory is the least severe warning of all. It means there's a chance of a flood that could inconvenience those in the area, but that it likely wouldn't be severe enough for the National Weather Service to issue an actual warning.

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People protecting themselves from the rain along Second Avenue in New York City May 16. Heavy rains and possible flooding are expected along the East Coast July 24 and 25. Hector Retamal/AFP/Getty Images