Tropical Storm Isaias has formed in the Gulf of Mexico and could reach the U.S. Gulf Coast as a hurricane on Friday, according to the National Hurricane Center.

Hurricane, tropical storm and storm surge watches cover parts of the coast. The hurricane watch extends from Bay St. Louis, Mississippi, to Indian Pass, Florida. The storm surge watch runs from the mouth of the Mississippi River to Yankeetown, Florida.

Forecasters expect Isaias to pass north of Mexico’s Yucatan Peninsula on Thursday and strengthen rapidly before approaching the U.S. coast. If it becomes a hurricane, it would be the Atlantic basin’s first of the season. Isaias is the season’s ninth named storm.

The hurricane center forecasts 3 to 6 inches of rain from southeastern Louisiana to the Florida Panhandle, with up to 10 inches in some places. Rain could spread across the Southeast this weekend and into early next week.