Miami - Tropical Storm Ana has formed over the Atlantic and could strengthen as it heads toward the Leeward Islands, forecasters said Saturday.

The National Hurricane Center in Miami said Ana could trigger a tropical storm watch for parts of the Leeward Islands later Saturday. It may pick up speed and approach the islands by Monday, the hurricane center said. It was 1,010 miles east of the islands early Saturday.

Ana, the first named storm of the Atlantic season, could slowly strengthen in the next couple of days as it moves to the west at 16 mph. Maximum sustained winds are near 40 mph.

Meanwhile, Hurricane Guillermo was swirling in the Pacific as a Category 3 storm. Winds were near 115 mph as the hurricane moved to the west-northwest at 16 mph. It was about 1,450 miles west of the southern tip of Mexico's Baja California peninsula early Saturday morning.

However, Guillermo was expected to weaken Saturday and become even less powerful Sunday as it moves over cooler waters.