A flash flood watch is in effect through Friday morning, the National Weather Service reports.
The Lowcountry is also under a tropical storm warning as Andrea, the first named storm of the season, barrels up the eastern coast, the Weather Service said.
The Charleston area can expect a bulk of moisture to hit the eastern seaboard this morning and through Friday, meteorologist Julie Packett said.
The heavy rain will cause flooding issues for motorists, she said.
Charleston police Cpl. Fred Bowie said the department has personnel out surveying area thoroughfares for flooding this morning.
High water is currently on Fisburne Street near Ashley Avenue, he said. The Septima P. Clark Expressway, also known as the Crosstown, is down to one lane in each direction.
“Certainly conditions can change rapidly with changes in tides and rainfall. Motorists are advised to exercise caution and to expect delays,” Bowie said in an email.
The Weather Service reports a near 100 percent chance of thunderstorms and showers.
“We had some heavy rain showers earlier which have either diminished or moved off the coast. Expect some additional development late this morning. Anything that does develop will have the potential to cause local flooding,” Packett said.
Winds will also pick up along the coastal areas tonight through early Friday, Packett said.
Highs today will be about 80 with lows about 70. Southeast winds will be from 15 to 20 mph with gusts up to 40 mph after midnight.
Friday: Tropical storm conditions are possible with a near 100 percent chance of showers and thunderstorms. Highs will be in the mid 80s with lows in the mid 70s. Southwest winds will be from 10 to 15 mph with gusts up to 25 mph.
Saturday: Mostly cloudy skies are expected with a 20 percent chance of showers and thunderstorms. Highs will be in the mid 80s with lows about 70.