The forecast

Today: Showers likely, and possibly a thunderstorm. New rainfall amounts between a quarter inch and a half inch with higher amounts possible.Thursday: A chance of showers and thunderstorms. New rainfall amounts between a tenth of an inch and a quarter-inch, except higher amounts possible in thunderstorms.Friday: A slight chance of showers and thunderstorms. Drier weather pattern sets in.Updates: Go to postandcourier.com/weather.

The streets of downtown Charleston went the way of the boats Tuesday.

Kayakers paddled through the City Market. Wakeboarders were towed over flooded pavement. And dozens of cars stalled in floodwater on the Septima P. Clark Parkway.

To blame was heavy rainfall that Tropical Storm Isaac sucked in from the tropics, and there could be plenty more this week where that came from. More than 7 inches was recorded on Daniel Island and about 5 inches downtown, according to the National Weather Service.

Meteorologists expect more downpours through Thursday.

“If you have a small sedan, you're not going to make it through this,” downtown resident Judge Kelly, 22, said as he directed cars to turn away from a flooded King Street. “I hope we don't end up like Venice.”

The parkway, where drainage improvements were touted to alleviate flooding, was still closed late Tuesday. Flower- pots, part of the effort to beautify the roadside, floated in the floodwaters.

In May, workers completed the initial phase of a $154 million drainage project for the roadway.

City officials have said Crosstown drainage will get progressively better as each part of the work moves forward toward completion in 2020.

Meanwhile, a half-dozen cars were flooded to their windows Tuesday near the Ashley Avenue intersection.

Samy Rugema had just left work at the Medical University of South Carolina when his Chevrolet Cavalier encountered 3 feet of water on the parkway, also known as the Crosstown. He regretted trying to make it through.

“All of a sudden, my car won't move,” Rugema said as he looked under the hood of his car. “It won't go forward or backward. (The water) was all the way above my tires.”

Tuesday's rainfall was concentrated in Charleston and in parts of Berkeley County.

“It's a peripheral effect of Isaac,” said Blair Holloway, a meteorologist at the Weather Service office in North Charleston. “The general circulation around the system helped push some very deep tropical moisture into the area.”

Holloway said Charleston was fortunate that the heaviest rainfall occurred near low tide, which was at 11:30 a.m. in Charleston Harbor.

“It could have been considerably worse,” he said. “But it's going to be real active the rest of the week, with lots of periods of rainfall.”

The weather ruptured a sewer line, causing traffic headaches and fouling the air near Long Grove Drive in Mount Pleasant. Long Grove, which runs south of Rifle Range Road, was expected to be closed through this afternoon, and police urged motorists to avoid the area.

During the height of the storm the Charleston Police Department recommended that motorists stay put. Downtown Charleston descended into gridlock.

Brian Boyd, 28, who lives in an apartment at the Crosstown and Kracke Street, watched traffic back up for miles as motorists feared driving through a newly formed lake.

Nearby, a Ford Taurus had been abandoned. Water flowed through an open window. Its headlights remained on.

“This is the first real big storm that's come through,” Boyd said. “I thought for sure that (U.S. Highway) 17 had been taken care of. ... Unless you have a big car, you're still going to get stuck.”

Daniel Prenner, an attorney, stepped outside his office at King and Line streets and threw sandbags against a doorway. Cars, trucks and a fire engine rushing by sent waves crashing over the sidewalk and into his building.

“This is the first time we've experienced anything like this,” Prenner said. “The main thing is the cars coming through and making a wake.”

Reach Andrew Knapp at 937-5414 or twitter.com/offlede.

Storify

[View the story "Charleston flooding" on Storify]