Tropical Storm Sally strengthened off the west coast of Florida on Sunday and was poised to become a hurricane, bringing the threat of dangerous storm surges and high winds to the U.S. Gulf Coast, the National Hurricane Center (NHC) said.
The storm track was disrupting oil production in the U.S. Gulf of Mexico for a second time in less than a month. The Miami-based NHC said the storm was likely to reach hurricane strength on Monday, and approach the north-central Gulf Coast late on Monday and Tuesday.
Hurricane conditions were expected by early Tuesday from Grand Isle, Louisiana to Ocean Springs, Mississippi, including New Orleans, the center said.
As of 2 p.m. ET (1800 GMT) on Sunday, Sally was about 140 miles (230 km) south-southwest of Apalachicola, Florida, and heading west-northwest with top sustained winds of 60 miles per hour (95 kph).
Sally carried the danger of storm surges – when the ocean rises at the coast over normal tide levels – of up to 11 feet (3.35 m), and rainfall of up to 12 inches (30 cm), the center said.
The storm follows Laura, which rampaged across the Gulf of Mexico three weeks ago and grew into a Category 4 hurricane with 150 mph (240 kph) winds. It shut hundreds of offshore oil facilities, leveled coastal Louisiana towns and left residents of Louisiana and Texas without power for weeks.
Oil companies evacuated staff from some offshore platforms on Saturday as Sally reached warm Gulf of Mexico waters.
Chevron Corp and Murphy Oil Corp evacuated offshore production platforms, and Chevron was preparing to halt output at two, spokespeople said. Chevron said its Pascagoula, Mississippi, refinery was following storm preparedness procedures.
Offshore oil producers Hess, BP, BHP and Occidental Petroleum said they were monitoring the storm and prepared to take actions. Laura halted up to 1.5 million barrels per day of output and a half dozen refineries, two of which are still in the process of making repairs.
Grand Isle, Louisiana went from voluntary to mandatory evacuation on Sunday.
Further off in the Atlantic Ocean, Hurricane Paulette was moving closer to Bermuda, and was expected to move near or over the island on Monday morning, the NHC said. Paulette was carrying top sustained winds of 75 mph (120 kph) and was expected to strengthen during Sunday.