Tropical storm Sally will move over the north-central Gulf of Mexico on Monday before becoming a hurricane as it heads toward south eastern Louisiana, the United States National Hurricane Center (NHC) said.

“Strengthening is expected over the next day or so, and Sally is forecast to become a hurricane by tonight, with additional strengthening possible before the center crosses the northern Gulf Coast,” the Miami-based weather forecaster added.

The second storm in less than a month to threaten the region, Sally is forecast to strengthen on Monday and bring heavy rains and winds of up to 85 miles per hour (137 km/h).

Mississippi and Louisiana issued mandatory evacuation orders to residents of low-lying areas, and Louisiana Governor John BelEdwards appealed for a federal disaster declaration and advised people living in Sally’s path to flee.

Residents of southwest Louisiana are still clearing debrisand tens of thousands of homes are without power after Hurricane Laura left a trail of destruction.

Energy companies scrambled to pull workers from offshore oil and gas production platforms. Chevron Corp, Equinor and Murphy Oil Corp shut in wells as a precaution, and refiner Phillips 66 halted processing at its Alliance refinery on the Louisiana coast.

At 7 am CDT, Sally was 115 miles southeast of the mouth of the Mississippi River, packing winds of 65 miles per hour, according to the NHC.

It warned the storm’s advance would slow in the next two days, dumping 8- to 16-inches (20-40 cm) on the coast and causing widespread river flooding.