Tropical Storm Gordon is continuing to strengthen and is expected to become a hurricane later on Tuesday when it hits the central US Gulf Coast.
Gordon formed into a tropical storm near the Florida Keys early on Monday as it lashed the southern part of the state with heavy rains and high winds.
The storm was centred 230 miles east-southeast of the mouth of the Mississippi River, forecasters said early on Tuesday morning. Maximum sustained winds were recorded at 65mph.
A hurricane warning was put into effect for the area stretching from the mouth of the Pearl River in Mississippi to the Alabama-Florida border.
As much as eight inches of rain could fall in some parts of the Gulf states through to late Thursday.
The Miami-based National Hurricane Centre said the storm is also expected to bring “life-threatening” storm surge to portions of the central Gulf Coast.
A storm surge warning has been issued for the area stretching from Shell Beach, Louisiana, to Dauphin Island, Alabama. The warning means there is danger of life-threatening inundation. The region could see rising waters of 3-5 feet.
“The deepest water will occur along the immediate coast near and to the east of the landfall location, where the surge will be accompanied by large waves,” the centre said.
Louisiana Gov John Bel Edwards declared a state of emergency on Monday and said 200 National Guard troops will be deployed to south-eastern Louisiana.
The storm’s predicted track had shifted slightly east as of Monday evening, meaning Louisiana is currently just outside the area under the hurricane warning.
But the south-eastern part of the state remains under a tropical storm warning and residents need to be prepared for the storm to shift west, Mr Edwards said.
“This storm has every possibility to track further in our direction,” Mr Edwards said during a news conference on Monday evening.
New Orleans Mayor LaToya Cantrell held an afternoon news conference and said the city has “the pumps and the power” needed to protect residents.
But authorities issued a voluntary evacuation order for areas outside the city’s levee protection system, including the Venetian Isles, Lake Saint Catherine and Irish Bayou areas.
Miami Beach Police said via Twitter that the Labour Day holiday was “NOT a beach day,” with rough surf and potential rip currents.
Red flags flew over Pensacola-area beaches in Florida’s Panhandle, where swimming and wading in the Gulf of Mexico was prohibited.
The National Weather Service said conditions were “possible” for tornadoes in the affected parts of South Florida on Monday night.