MEXICO CITY — Adrian, the first tropical storm of the eastern Pacific hurricane season, formed Tuesday off Mexico’s western Pacific coast.

The U.S. National Hurricane Center said Adrian had sustained winds of 45 mph. The storm was expected to strengthen, but keep heading out to sea.

On Tuesday afternoon, the storm’s center was located about 280 miles south-southwest of the Pacific coast seaport of Manzanillo, Mexico.

The center said Adrian was moving west at about 15 mph, and that general motion was expected to continue. Adrian was expected to build to hurricane strength by Wednesday, but would likely weaken again to a tropical storm by the weekend.