Mario Leiva, 75, uses a stick in an attempt to unblock the sewer drainage in Miami on Saturday. AP
Officials in Miami warned drivers about road conditions as many cars were stuck on flooded streets.
"This is a dangerous and life-threatening situation. Travelling during these conditions is not recommended. It’s better to wait. Turn around, don’t drown,” the city of Miami Mayor tweeted.
The city was towing stranded vehicles from flooder roadways.
Miami Beach Mayor Dan Gelber said the storm tested the system of drainage pumps the city has recently installed as climate change has increasingly made flooding an issue in the low-lying area.
Rainfall from Tropical Storm Alex floods the Brickell area near downtown Miami on Saturday. AP
"We moved the water off pretty quickly, but in some areas, obviously, it was really challenging,” Gelber said. "There were some problems getting through on some streets, one of the main arteries was unpassable, but by and large water is dissipating.”
The National Hurricane Center in Miami said the storm once known as Agatha in the Pacific Ocean will be known as Alex in the Atlantic Ocean basin, if it reaches tropical storm status.
As of about 11pm on Saturday, the storm was centered about 145 miles (235 kilometres) east-northeast of Fort Pierce, Florida. It was moving northeast near 20 mph (31 kph). Tropical storm warnings that had been in effect for Florida's east coast and the northwestern Bahamas were discontinued. A tropical storm watch was in effect for Bermuda. Maximum sustained winds were clocked near 45 mph (75 kph) with higher gusts.
The storm was expected to reach tropical storm strength off Florida’s eastern coast Saturday night and strengthen through Monday as it moves away from Florida and into the Atlantic Ocean.