Mel Evans, Associated Press
New Jersey Gov. Chris Christie listens to a question as he announces preparation plans for a possible weekend rainstorm Thursday, Oct. 1, 2015, in Trenton, N.J. Governors up and down the East Coast are warning residents to prepare for drenching storms as flooding killed one person Thursday in South Carolina. The rains could cause power outages and close roads in a region already walloped by rain. Hurricane Joaquin's approach could intensify the damage, but rain is forecast across the region regardless of the storm's path. Listening in the background are Elizabeth Connolly, left, Acting Commissioner of Department of Human Services, Richard S. Mroz, second left, President of the New Jersey Board of Public Utilities, and Dr. Chris Rodriguez, right, Director of New Jersey Office of Homeland Security.

RALEIGH, N.C. — One person died Thursday as heavy flooding submerged cars and closed streets in South Carolina, and the drenching storms were expected to move up the East Coast, a region already swamped by rain.

Governors up and down the coast warned residents to prepare. The rains could cause power outages and close more roads. The approach of Hurricane Joaquin — a major Category 4 storm set to wallop the Bahamas and move toward the U.S. — could intensify the damage, but rain is forecast across the region regardless of the storm's path.

New York Gov. Andrew Cuomo said Thursday that the state is already moving equipment, including generators and pumps, into position while state emergency officials watch the storm's progress. Upgrades and repairs made after Superstorm Sandy and Hurricane Irene have made New York and New York City better prepared for the next tropical storm, Cuomo said.

In Spartanburg, South Carolina, the heavy rains flooded and closed streets. Several cars were submerged in flash floods. One man was rescued Thursday morning after his vehicle was swept off the road where a culvert had washed out, Doug Bryson with Spartanburg County Emergency Management told local news outlets. The man managed to cling to a tree and was taken to a hospital for treatment, though there was no immediate word on his condition.

Spartanburg County Coroner Rusty Clevenger said 56-year-old Sylvia Arteaga of Spartanburg died Thursday morning. She was driving underneath an overpass just outside city limits when her car flooded "to capacity" inside.

Meanwhile, Hurricane Joaquin was bearing down on the Bahamas, and forecasters said the storm is likely to strengthen as it makes its way toward the U.S.

But no matter which way Joaquin heads, an area of low pressure in the Southeast and a front stalled over the East Coast will pull moisture from the Atlantic Ocean, causing rain over the next few days, said Bruce Terry, lead forecaster for the government's Weather Prediction Center. The National Weather Service predicts as much as 10 inches for some areas.

"The bottom line is: We are expecting very heavy rains all the way from the Carolinas up into New England," he said.

The heaviest rain is expected in wide swaths of North Carolina and Virginia, along with parts of Maryland, Delaware and New Jersey, according to a National Weather Service forecast map.

The National Weather Service issued flash flood watches for Washington D.C., northern Virginia, southern Maryland and the Eastern Shore from Friday morning through late Saturday. Coastal flood warnings and advisories are in effect during the same period in central and southern Delaware and on the Eastern Shore.

In North Carolina, Gov. Pat McCrory declared a state of emergency Thursday and said emergency management officials are preparing for expected floods by readying supplies and going over readiness checklists.

Virginia Gov. Terry McAuliffe declared a state of emergency Wednesday afternoon, which allows emergency responders to begin to prepare for the storms.

He also issued tips to residents, including that "when roads are flooded, turn around and drive to a safe location.

"It may save your life."

In New Jersey, Gov. Chris Christie also declared a state of emergency. New Jersey has been hit by intermittent heavy rains and strong on-shore winds the last few days, and that's expected to continue, especially Friday and Saturday.

Officials were closely watching the progress of the hurricane, though its path was far from certain. So far, there's been little consensus among computer-prediction models for the hurricane.

The National Hurricane Center in Miami sent a plane aloft Wednesday to gather data about Joaquin that will hopefully "get those models into better agreement," said Rick Knabb, the center's director.

"We're going to be throwing a lot more aircraft resources at this problem over the next few days," he said.

In New England, hundreds of cars were damaged by high water around the region, with some of them totaled and others needing expensive repairs, officials said Thursday. More than 6 inches of rain fell Wednesday in Maine, while New Hampshire got more than 5 inches. Vermont also got heavy rain, but not as much.

Associated Press video journalist Tony Winton in Miami and AP writers Martha Waggoner in Raleigh; John Raby in Charleston, West Virginia; Meg Kinnard in Columbia, South Carolina; and Amy Anthony in Providence, Rhode Island, contributed to this report.