WASHINGTON - The first tropical storm of the year formed in the Pacific Ocean southwest of Mexico on Monday and was named Aletta, the Miami-based National Hurricane Center said. 

The storm had maximum sustained winds early Tuesday near 40 mph with additional strengthening forecast during the next day or so followed by gradual weakening. 

The storm is swirling far out over the Pacific and is not posing a danger to land. Aletta is centered about 640 miles south-southwest of Manzanillo, Mexico, and is moving west-northwest near 9 mph.

The storm's forecast track shows it going farther out to sea. 

The Atlantic storm season has yet to begin. June 1 is the official start of the Atlantic season, though storms can form before or after that date.

For Pacific storms, the other names being used this year are: Bud, Carlotta, Daniel, Emilia, Fabio, Gilma, Hector, Ileana, John, Kristy, Lane, Miriam, Norman, Olivia, Paul, Rosa, Sergio, Tara, Vicente, Willa, Xavier, Yolanda and Zeke.

Reuters contributed to this report.

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