The storm will likely sweep quickly through the Gulf, keeping production impacts shortlived. But it could drop as much as 10 inches (25 centimeters) of rain in Louisiana and Mississippi over seven days, according to the U.S. Weather Prediction Center in College Park, Maryland.

“This system could produce storm surge and tropical-storm or hurricane-force winds across portions of the Louisiana, Mississippi and upper Texas coasts later this week, and interests there should closely monitor its progress,” Stacy Stewart, a senior hurricane specialist at the center, wrote in a bulletin.

The Gulf offshore region accounts for 17% of U.S. crude oil output and 5% of dry natural gas, according to the Energy Information Administration. More than 45% of U.S. refining capacity and 51% of gas processing is along the Gulf coast.

Chevron Corp. said Tuesday that it began shutting in five of its platforms in the Gulf and is starting to evacuate all associated personnel. Royal Dutch Shell Plc slightly reduced production on two platforms and is evacuating non-essential personnel. BP Plc also began removing offshore personnel and shutting in some production.

“Tropical storm or hurricane watches likely to be issued across the northern Gulf,” Jim Rouiller, chief meteorologist at the Energy Weather Group in Philadelphia, said in an email. “This will spark widespread shut-ins across the entire production region.”