The National Hurricane Center (NHC) said Sally has been downgraded to Category 1 and is moving forward with maximum sustained winds of 140 kilometers per hour.
“Sally may produce potentially life-threatening flash floods through Wednesday,” the Miami-based NHC warned.
At 12:00 GMT, Sally was 170 km southeast of Biloxi on the Mississippi coast, heading northwest at 3.2 km / h. The hurricane is expected to make landfall on Tuesday night or early Wednesday morning.
President Donald Trump compared Sally to Hurricane Laura, which hit Texas and Louisiana, as well as the Caribbean, just a few weeks ago.
“This one is smaller but it’s a little more direct, but we have everything under control,” he said. “We are monitoring it very rigorously.”
He also said on Twitter that “my team and I are monitoring the extremely dangerous Hurricane Sally.”
“We are in close contact with State & Local Leaders to assist the great towns of Alabama, Louisiana and Mississippi,” he added, urging people living in the path of the hurricane to attend to authorities.
Alabama and Mississippi declared a state of emergency.
Mississippi Governor Tate Reeves said Hurricane Sally is expected to make landfall around Biloxi at 0200 local time (0600 GMT) on Wednesday.
“Storm surge projections continue to be worrisome, with coastal storm surges between five and eight feet (1.5 to 2.4 meters),” Reeves wrote.
“We remain very concerned about the amount of rain,” he added, detailing that some areas could receive up to 50 centimeters.
Louisiana Governor John Bel Edwards, whose state has not yet recovered from Laura’s scourge, which struck as a Category 4 hurricane, urged residents to be prepared.
“Be smart and stay safe,” he tweeted.
But the NHC predicts that Sally will turn north, away from southeastern Louisiana, to make landfall along the southern coast of neighboring Mississippi and Alabama.
There have been so many tropical storms in the Atlantic this year that the UN World Meteorological Organization, which names them, is about to run out of names for the second time in history.
The last time was in 2005, the year Hurricane Katrina devastated New Orleans.
Sally, which formed in southern Florida, where it produced heavy rains over the weekend, is one of five cyclones currently active in the Atlantic, a phenomenon that was only recorded once before, in September 1971, according to meteorologists. .
The others are Hurricane Paulette, Tropical Storms Teddy and Vicky, and Tropical Depression Rene.
Paulette hit the island of Bermuda on Monday with Category 2 winds and heavy rain, according to the NHC.
The center also expects Teddy to become a hurricane on Tuesday.