Flood advisories were issued for the Carolinas, Virginia, West Virginia, Maryland, Pennsylvania, New York, Vermont, and New Hampshire, as well as Washington.
The storm is forecast to weaken as it moves into the Carolinas but will “produce an additional 4 to 8 inches of rainfall with locally higher amounts, across portions of southeastern North Carolina leading to maximum storm total amounts as high as 15 inches,” the agency said.
In Virginia, 3 to 7 inches of rainfall with local amounts of up to 10 inches are expected through Friday, it said. And from portions of Maryland into upstate New York and Vermont, between 2 and 4 inches of rainfall, with local amounts of up to 6 inches are expected through Friday evening, according to the NWS.
“Rain, wind, and thunderstorms should come to an end on Saturday when Debby gets swept up into a powerful upper low propagating across southern Canada,” forecasters said.
While Debby produced less rain on Wednesday than the previous days, it could pick up again on Thursday, said Rich Bann, a meteorologist with the NWS.
“Moisture has pulsed back into Debby,” Bann said, as it spent the last day parked over the Atlantic Ocean. “As Debby makes its way inland … the threat of heavy rains will lead to flooding concerns,” he added.
More than 141,000 customers were without power in the Carolinas and Virginia on Thursday morning, according to the tracking site Poweroutage.us. About 17,000 remained without power in Florida, down from a peak of 350,000.
An apparent tornado killed one man when his house collapsed as it tore through eastern North Carolina and damaged at least 10 houses, a church, and a school in Wilson County early on Thursday morning, county officials reported on social media.
The system could spawn tornadoes in the region on Thursday, the National Hurricane Center (NHC) said.
Emergency management officials are keeping a close watch as rainwater drains into the numerous river systems in the Carolinas over the coming days, posing the risk of major flooding long after the storm exits.
The Virginia Department of Emergency Management posted on social media that locals should be alert for potential tornadoes on Thursday and Friday.
More than 140,000 customers were without power in the Carolinas and Virginia on Thursday morning, according to Poweroutage.us. About 13,000 remained without power in Florida, down from a peak of 350,000.
As Debby continues to churn its way up the East Coast, the NHC wrote Thursday that it will be monitoring a developing system near a grouping of islands east of the Caribbean Sea. There is a 30 percent chance of a named storm being formed for the coming week, it said.
“An area of low pressure could form in the central or western tropical Atlantic Ocean early next week. Some development of this system is possible while it approaches the Lesser Antilles during the early to middle part of next week and moves generally west-northwestward toward the Greater Antilles thereafter,” the NHC said.
Reuters contributed to this report.