A stricken cargo ship with 28 Americans on board that vanished during Hurricane Joaquin remained missing early Saturday as forecasters warned a separate storm would bring a once-in-200 year rainfall event to South Carolina.

As much as 12 inches of rain fell overnight in Wilmington, North Carolina, and numerous water rescues were reported. Heavy rain was expected over cities including Charleston, Columbia and Charlotte.

The National Weather Service warned that South Carolina could even face a “once every 500 years” drenching this weekend, adding that “record rainfall and life-threatening flash flooding” were possible through Sunday.

“A significant flooding event is developing across southern South Carolina and portions of eastern Georgia,” the NWS said. “A powerful low-pressure system over the southeast United States will slowly move northeast across the area through Sunday. Accompanying this storm will be several weather hazards, most notably the potential for dangerous flooding from heavy rainfall and high tides.”

The NWS predicted “several rounds of abnormally high tides” in South Carolina and Georgia from Friday night through Sunday.

“The highest tides are expected early Saturday afternoon, potentially into Saturday night,” it added.

“Periods of heavy rain will affect southern South Carolina and eastern portions of Georgia,” the NWS said. “There is increasing confidence that a significant heavy rainfall event will occur through Sunday with some locations seeing record rainfall amounts.”

A stretch from Charleston, South Carolina, to Washington, D.C., is expected to be deluged as a result of a weather pattern called a “Rex Block,” which is forecast to bring heavy rain to the area’s already-oversaturated grounds.

Meanwhile, there was still no sign of the cargo ship El Faro, which was last heard from around 7:20 a.m. Thursday when a distress call from the ship indicated it had lost power and was taking on water.

The 735-foot vessel was bound for San Juan in Puerto Rico from Jacksonville, Florida, at the time. It was carrying 28 Americans and five Polish nationals.

Around 850 square nautical miles were searched on Friday and the effort was due to continue from first light Saturday, the coast guard said.

When the El Faro left Jacksonville on Tuesday Joaquin was just a tropical storm. It quickly grew in intensity and was declared a Category 4 storm Thursday as it approached the Bahamas carrying winds of 130 mph.

Anthony Chiarello, president and CEO of ship owner TOTE, said late Friday that he had met with the crew members’ families.

Image: Cargo ship El Faro missing in Hurricane Joaquin

Image: Cargo ship El Faro missing in Hurricane Joaquin

“Our number one priority … is the safe return of the 33 people on the vessel,” he told a press conference.

Chiarello said the firm was working with the coast guard and that everything “humanly possible” was being done to find and recover the ship.

Company officials noted that the El Faro’s captain “is a man of incredible experience” who has spent more than two decades at sea.

The El Faro had lost propulsion and was listing at 15 degrees when it was last heard from. At the time, its crew said the vessel had taken on water but all flooding had been contained, the coast guard said.

TOTE said the majority of the Americans aboard were based around Jacksonville, Florida.

Joaquin remained a Category 3 hurricane early Saturday and by 5 a.m. ET was centered about 120 miles northeast of San Salvador, Bahamas, and about 700 miles southwest of Bermuda. It had maximum sustained winds of 125 mph and was moving northeast at 13 mph.

Earlier models showed the U.S. could possibly get a direct hit from the storm in the coming days, but the latest predictions show Joaquin offshore.

A hurricane warning was still in effect for parts of the Bahamas.