Tropical Storm Isaias forecast to hit U.S. Gulf coast as hurricane early Saturday

Tropical Storm Isaias formed early Wednesday in the warm waters off eastern Mexico and forecasters said it was expected to strengthen into the first hurricane of the Atlantic season before hitting the U.S. Gulf Coast later in the week.

Isaias was located about 285 miles (460 kilometers) west of Progreso, Mexico, and about 580 miles (935 kilometers) southwest of the Mississippi River's mouth, according to the Miami-based National Hurricane Center. It had maximum sustained winds of 40 mph (65 kph) and was moving east-northeast at 8 mph (13 kph).

It was not immediately known where the storm may make landfall on the Gulf Coast. The hurricane center's initial projections said the center of Isaias could come onshore somewhere between eastern Louisiana and the western Florida Panhandle. People in those areas were urged to prepare for the storm.

"There is an increasing risk of dangerous wind and storm surge impacts along portions of the northern Gulf Coast," the hurricane center said. "Residents from Louisiana to the Florida Panhandle should closely monitor the latest forecast updates and ensure they have their hurricane plan in place."

Isaias also will bring areas of heavy rain to portions of the Gulf Coast and much of the U.S. Southeast on Friday and into the weekend, forecasters said.

The storm comes as the Atlantic hurricane season has been unusually quiet this year due to a strong El Niño, which disrupts storm formation over that ocean. Storm activity in the Pacific has been above average.