The images of Laura's destruction in Santo Domingo 3:59
(CNN) - As one storm heading toward the US Gulf Coast weakens, another grows stronger.
Louisiana is likely to be spared the double hit of consecutive hurricanes this week, as Marco downgraded to a tropical storm Sunday night. But the state is still in the path of Tropical Storm Laura, which is expected to become a hurricane before making landfall in the United States.
Previously, both storms were predicted to hit the Louisiana coast as hurricanes just miles apart and within a 48-hour period, an event unlike any other in modern meteorological history, said National Weather Service meteorologist Benjamin. Schott.
But Marco is currently facing unfavorable conditions that make a return to hurricane force unlikely, CNN meteorologist Robert Shackelford said. And although it could reach Louisiana with a landfall Monday night or Tuesday morning, the storm could disappear as it moves parallel to the coast, he said.
LOOK: Hurricane Marco degrades to a tropical storm while a double threat points to Louisiana
Meanwhile, tropical storm Laura, which has already proven to be deadly in the Dominican Republic, is strengthening in the warm waters of the Caribbean and is likely to become a hurricane the Tuesday. By Wednesday, Laura could hit Louisiana as a Category 2 storm.
'There may not be much margin'
If the conditions are right for both Marco and Laura to hit land, the effects could pose a challenge to Louisiana officials and residents.
With such a tight time frame, "there may not be much scope" for rescuers or power restoration teams to respond to casualties between the two storms, Louisiana Gov. John Bel Edwards said.
In the early hours of Monday, Tropical Storm Marco was about 150 miles south-southeast of the mouth of the Mississippi River with maximum sustained winds of 104 miles per hour. The storm is moving at 12 miles per hour toward the river's mouth, according to the National Hurricane Center.
Also with sustained winds of 104 kilometers per hour, Tropical Storm Laura was about 96 kilometers south of Camagüey, Cuba, on Monday morning. The storm was moving from west to northwest at 33 kilometers per hour.
Before Marco weakened, mandatory evacuations were issued Sunday for Plaquemines Parish, Louisiana, and Grand Isle, Louisiana. Hurricane warnings have been suspended and warnings off the Louisiana coast have been changed to tropical storm warnings.
Meanwhile, Tropical Storm Laura has parts of Cayman, Cuba, and the Florida Keys under tropical storm watches and warnings. Hurricane warnings will likely be issued on Monday.
MIRA: Three people die from floods caused by Laura in Santo Domingo
Life-threatening storm surge
The hurricane center issued a storm surge warning for coastal cities from Morgan City, Louisiana, east to Ocean Springs, Mississippi, and forecasters warned that storm surge could be "life threatening."
"Ultimately, the big concern will be storm surge," said CNN meteorologist Allison Chinchar.
Although degraded, Marco is still expected to be a dangerous storm, bringing tropical force winds, heavy rain, flash floods and isolated tornadoes. It could even bring a swell of up to 6 feet on the Gulf Coast, along with "an enormous amount of rain," Chinchar said.
And Laura is expected to come shortly after.
"Even on Monday and Tuesday, in Key West, Miami, you'll get some of those outer bands from Laura that will produce very heavy rain and very gusty winds," Chinchar said.
Before it reaches the US, Laura is expected to bring up to a foot of rain to parts of the Caribbean.
The Dominican Republic already experienced Laura's wrath on Sunday. At least nine people have died in the Caribbean from the storm, at least three in the capital Santo Domingo, according to the country's Emergency Operations Center.
The victims in the capital include a 7-year-old boy who died with his mother after a wall collapsed in their house and a third person who died after a tree fell on a house.
LOOK: Tropical storm Laura: the images of the destruction caused in Santo Domingo
Dominican Republic President Luis Abinader said Sunday that an army corporal died while helping with rescue efforts in Pedernales province.
Five people died in Haiti, according to the country's Civil Protection, including a 10-year-old girl.
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