» Tropical Storm Laura kills 11 as it moves through Hispaniola.

NEW ORLEANS — Tropical Storm Marco began falling apart Monday, easing one threat to the Gulf Coast but setting the stage for the arrival of Laura as a potentially supercharged Category 3 hurricane with winds topping 110 mph and a storm surge that could swamp entire towns.

The two-storm combination could bring a history-making onslaught of wind and coastal flooding from Texas to Alabama, all complicated by the coronavirus pandemic, forecasters said.

Still a tropical storm for now, Laura churned just south of Cuba after killing at least 11 people in the Dominican Republic and Haiti, where it knocked out power and caused flooding in the two nations that share the island of Hispaniola.

The deaths reportedly included a 10-year-old girl whose home was hit by a tree and a mother and young son who were crushed by a collapsing wall.

Laura was not expected to weaken over land before moving into warm, deep Gulf waters that forecasters said could bring rapid intensification.

Shrimp trawlers and fishing boats were tied up in a Louisiana harbor ahead of the storms. Red flags warned swimmers away from the pounding surf. Both in-person classes and virtual school sessions required because of the coronavirus pandemic were canceled in some districts.

State emergencies were declared in Louisiana and Mississippi, and shelters were being opened with cots set farther apart, among other measures designed to curb infections.

The double punch comes just days before the Aug. 29 anniversary of Hurricane Katrina, which breached the levees in New Orleans, flattened much of the Mississippi coast and killed as many as 1,800 people.

For the residents of the Louisiana coast, “they’re certainly lucky that Marco is not worse than it is,” said University of Miami hurricane researcher Brian McNoldy.

“This will come and go, and they can get ready for Laura. That’ll be the main attraction.”

Meanwhile, Laura drenched much of Cuba as it headed northwest at 20 mph with top sustained winds of 60 mph.

Photos by Dieu Nalio Chery / Associated Press A girl wades toward her flooded home Monday, the day after the passing of Tropical Storm Laura in Port-au-Prince, Haiti. Laura battered the Dominican Republic and Haiti on its way to the Gulf Coast.

Yoleine Toussaint, 22, removes mud from plates in front of her flooded house Monday after Tropical Storm Laura slammed Port-au-Prince, Haiti.