(Bloomberg) -- Severe thunderstorms forced the Federal Aviation Administration to reroute airplanes across the eastern US Monday while warning that departing flights might be paused as a line of heavy rains stretched from the Deep South to New England. 

Flights out of Atlanta, Charlotte, Washington, Philadelphia and the New York City area could all see their departures delayed, the FAA cautioned in a post on the X social media platform formerly known as Twitter. The worst of the storms were expected to develop in southern Pennsylvania, West Virginia, Virginia, Maryland, the US Storm Prediction Center said.“This is a really potent storm system coming through especially for this time of year,’’ said Brian Hurley, a senior branch forecaster at the US Weather Prediction Center.The National Weather Service issued tornado and severe thunderstorm watches Monday afternoon for large swaths of the Eastern US from Pennsylvania to South Carolina. Some areas are warned to look out for damaging winds up to 75 miles (121 kilometers) per hour and hail that could reach 1.5 inches (3.8 centimeters) in diameter.

David Roth, a forecaster at the agency, said the storms may consolidate as they move east into a squall line, a group of storms arranged in a band.

“This should be ending tonight,” Roth said. “But when depends on where you are.” The Washington area can expect to be on watch until about 9 p.m. local time, while watches issued further north in New Jersey are effective until 11 p.m.Across the eastern US, 49.4 million people faced an enhanced risk of dangerous storms and flooding Monday, with an additional 38 million facing a slight risk, including New York City and Pittsburgh. The worst threat will likely be high winds, Hurley said.The West Virginia Emergency Management Division is warning residents to prepare for the storms and cautioning people to charge cell phones and have a way of receiving weather alerts, according to a social media post.

In other weather news:

Southern Europe: Extreme heat is returning to southern Europe this week, with the potential for record temperatures in parts of Spain, while further north a destructive storm is lashing the Nordic region.

Central Europe: Slovenia is beginning to assess the human and economic toll from flooding that’s inundated parts of the country as the Alpine nation of 2.1 million took the brunt of record rainfall in central Europe. 

China: Heavy rains lashing China’s northeast are ravaging crops in some areas of the country’s grain basket, threatening to increase imports at a time of rising food insecurity across the globe.

Tropics: Tropical Storm Khanun now looks to be veering away from Kyushu, the most south western of Japan’s main islands, and headed for Korea.

--With assistance from David R Baker and Cailley LaPara.

(Adds more details, including timing for East Coast storms, starting in fourth paragraph)

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