Airlines canceled more than 500 flights Saturday morning, including some to and from Miami and Fort Lauderdale airports, according to FlightAware.
The City of Miami-Fire Rescue tweeted a video of cars trapped in the water and said six high-water vehicles were helping motorists.
The National Weather Service (NWS) extended sudden flood warnings for Miami and Fort Lauderdale at least until 1 p.m.
“Between 6 and 11 inches of rain has fallen. Additional amounts of 2 to 5 inches may fall in the alerted area,” the NWS office in Miami said.
The potential Tropical Cycle One is poorly organized and has begun to traverse southern Florida, the National Hurricane Center (NHC) said. At 11 a.m. ET, it was about 35 miles northeast of Naples and about 100 miles southwest of Vero Beach.
Tropical storm warnings have been canceled for Cuba and parts of West Florida. Tropical storm warnings remain in effect for more than 7 million people along the east coast of Florida from the Volusia / Brevard County line to Card Sound Bridge and the northwestern Bahamas.
Cities under notice include Naples, Miami, Fort Lauderdale, West Palm Beach and Melbourne.
The disturbance is unlikely to become the first so-called storm of the Atlantic hurricane season before it ends across Florida on Saturday, the NHC says.
“The disturbance is expected to turn into a tropical storm off the east coast of Florida on (Saturday night) and some strengthening is expected tonight on Monday as the system moves away from Florida by the “Western Atlantic,” the NHC said.
Some places could see up to 15 inches before the end of Saturday; Miami was 11 inches at 9 p.m. The NHC also says “considerable and sudden urban flooding is expected” across the region.
“Over the past few hours, a Fowey Rocks weather station near Miami, Florida, has reported sustained winds of 46 mph and a gust of wind of 56 mph,” the NHC said.
A tropical storm warning means tropical storm conditions are possible.
A tropical storm warning was in effect Saturday morning in the Cuban provinces of Matanzas and Youth Island. This means that tropical storm conditions are expected.
And finally, a couple of tornadoes are possible on the southeast coast of Florida throughout Saturday.
Airlines canceled 841 flights on Friday amid multiple storm systems, FlightAware data show.
U.S. airlines have warned that disruptions at Florida airports would last until the weekend.
CNN’s Greg Wallace contributed to this report.