Already blamed for one death in Alabama, Cindy was expected to keep churning seas and spin off bands of severe weather from eastern Texas to northwestern Florida.
The storm's maximum sustained winds had decreased to near 40 mph (64 kph) Thursday morning with additional weakening expected, the U.S. National Hurricane Center said.
A boy on an Alabama beach was struck and killed Wednesday by a log washed ashore by the storm. Baldwin County Sheriff's Capt. Stephen Arthur said witnesses reported the 10-year-old boy from Missouri was standing outside a condominium in Fort Morgan when the log, carried in by a large wave, struck him. Arthur said the youth was vacationing with his family from the St. Louis area and that relatives and emergency workers tried to revive him. He wasn't immediately identified.
It was the first known fatality from Cindy. Otherwise, the storm was blamed for widespread coastal highway flooding, rough seas and scattered reports of power outages and building damage caused by high winds. There were numerous reports of waterspouts and short-lived tornadoes spawned by the storm.
National Weather Service forecasters estimated the storm had dumped anywhere from 2 to 10 inches (50 to 250 millimeters) of rain on various spots along the Gulf Coast from southern Louisiana to the Florida panhandle as of Wednesday. And more rain was on the way.
Alek Krautmann of the National Weather Service in Slidell, Louisiana, said Thursday's pattern would likely be much like Wednesday's: Bands of intermittent, sometimes heavy rain spinning onto the coast.
In Gulfport, Mississippi, Kathleen Bertucci said heavy rainfall Wednesday sent about 10 inches of water into her business, Top Shop, which sells and installs granite countertops.
"It's pretty disgusting, but I don't have flood insurance because they took me out of the flood zone," said Bertucci, whose store is near a bayou. "We're just trying to clean everything up and hope it doesn't happen again."
In nearby Biloxi, a waterspout moved ashore Wednesday morning. Harrison County Emergency Management Director Rupert Lacy said there were no injuries but fences, trees and power lines were damaged.
Storms also downed trees in the Florida Panhandle. Fort Walton Beach spokeswoman Jo Soria said fallen trees hit houses and cars in what she called "pockets of wind damage" in two or three residential neighborhoods.
The White House said President Donald Trump was briefed on the storm Wednesday by Homeland Security Adviser Tom Bossert.
Louisiana Gov. John Bel Edwards declared a state of emergency, like his Alabama counterpart a day earlier. He was among authorities stressing that the storm's danger wasn't limited to the coast.
In Knoxville, Tennessee, the power-generating Tennessee Valley Authority, said it was drawing down water levels on nine lakes it controls along the Tennessee River and its tributaries in Tennessee, Alabama and Kentucky, anticipating heavy runoff from Cindy's rains once the storm moves inland. The TVA manages 49 dams to regulate water, provide power and help control downstream flooding.
In Alabama, streets were flooded and beaches were closed on the barrier island of Dauphin Island. Some roads were covered with water in the seafood village of Bayou La Batre, but Becca Caldemeyer still managed to get to her bait shop open at the city dock. If only there were more customers, she said.
"It's pretty quiet," Caldemeyer said by phone from Rough Water Bait and Tackle. "Nobody can cast a shrimp out in this kind of wind."
Rough seas also led to the rescue of a shrimp trawler in danger of sinking off the coast of Texas. The U.S. Coast Guard said crew of the trawler Footprint was about 80 miles (130 kilometers) southeast of Galveston when the crew radioed that the vessel was taking on water faster than onboard pumps could clear it. A helicopter crew lowered and extra pump that enabled the shrimp boat crew to clear enough water to stay afloat. A Coast Guard cutter escorted the vessel to Freeport, Texas.
Associated Press writers Janet McConnaughey in New Orleans; Melinda Deslatte in Baton Rouge, Louisiana; Jeff Amy and Emily Wagster in Jackson, Mississippi; Jay Reeves in Birmingham, Alabama; Kimberly Chandler in Montgomery, Alabama; and Brendan Farrington in Tallahassee, Florida, contributed to this report.