MIAMI (AP) — The first tropical storm of the season has formed in the eastern Pacific off Guatemala and is headed for land.

The U.S. National Hurricane Center in Miami says Tropical Storm Agatha has maximum sustained winds of 40 mph (64 kph) and some strengthening is expected.

It is centered about 170 miles (275 kilometers) southwest of Puerto de San Jose, Guatemala, and moving toward the northeast at 5 mph (8 kph).

The center says the storm could dump 10 to 20 inches (25 to 50 centimeters) of rain and as much as 30 inches (75 centimeters) in isolated areas, threatening dangerous floods and mudslides.

A tropical storm warning was in effect Sunday for a stretch of coastline from El Salvador to far-southern Mexico.