New Orleans is prepping for a hurricane. The flooding has already hit.

On the same day that a National Oceanographic and Atmospheric Administration report warned Americans of a "floodier" future, some streets in Louisiana's largest city, including in the famed French Quarter, looked more like rivers.

Lines of thunderstorms associated with a weather system that is predicted to develop into a hurricane by Friday struck New Orleans with as much as 7 inches of rain within a three-hour period Wednesday morning, forecasters said.

The city was engulfed with water, leaving residents to contend with swampy streets, overturned garbage cans and flooded vehicles. Some even paddled their way down the street in kayaks.

Chandris Rethmeyer said she lost her car to the flood and had to wade through water about 4 feet deep to get to safety.

Rethmeyer said she was on her way home after working an overnight shift when she got stuck behind a car accident in an underpass and the water began to rise.

“I was going to sit in my car and let the storm pass,” she said. “But I reached back to get my son’s iPad and put my hand into a puddle of water.”

And Valerie R. Burton woke up Wednesday to what looked like a lake outside her door.

“There was about 3 to 4 feet of water in the street, pouring onto the sidewalks and at my door," Burton said. "So, I went to my neighbors to alert them and tell them to move their cars."

The tides were reminiscent of sudden flooding that took the city by surprise in August 2017. That flood not only required major repair efforts, but also exposed significant problems within the agency overseeing street drainage and lead to personnel changes at the New Orleans Sewerage and Water Board.

Forecasters said that Louisiana could see up to 12 inches of rain by Monday, with some isolated areas receiving as up to 18 inches.

That heavy rain could push the swollen Mississippi River dangerously close to the top of the city's levees, officials cautioned.

A spokesman for the Army Corps of Engineers in New Orleans said the agency was not expecting widespread overtopping of the levees, but there are concerns for areas south of the city.

The river was expected to rise to 20 feet by late Friday at a key gauge in New Orleans. The area is protected by levees 20 to 25 feet high, he said.

Louisiana Gov. John Bel Edwards declared a state of emergency: "The entire coast of Louisiana is at play in this storm," Edwards said.

Contributing: The Associated Press.