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DEVELOPING: Tropical Storm Claudette, the third of the Atlantic hurricane season, formed in the eastern Gulf of Mexico Sunday, according to the National Hurricane Center.

Claudette is expected to move ashore within hours in the Florida panhandle, and a tropical storm warning was issued Sunday for parts of Florida.

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A tropical storm warning was issued Sunday for parts of Florida as a newly formed depression swirled about 90 miles off the coast.

The warning was issued for areas east of the Alabama state line to the Suwanee River. The warning means tropical storm conditions are likely within the next 24 hours.

Forecasters at the National Hurricane Center said the depression was expected to be near Florida's northern Gulf Coast by Sunday afternoon. It was moving to the north-northwest at about 16 mph, with maximum sustained winds around 35 mph. It was about 90 miles from Tampa early Sunday morning.

Meanwhile, Hurricane Guillermo was swirling in the Pacific as a Category 2 storm. And tropical storms Ana and Bill were moving over the Atlantic.

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Guillermo had weakened slightly, with maximum sustained winds dropping to 100 mph. It was expected to lose more steam and dwindle to a tropical storm in the next day or two. It was moving west at 15 mph, about 1,150 miles east of Hilo, Hawaii.

Tropical Storm Bill had strengthened some, with winds picking up to 45 mph. It was expected to build momentum and become a hurricane in the next few days. But Bill was still far out in the Atlantic, moving west at 13 mph about 1,640 miles east of the Lesser Antilles.

The Leeward Islands were keeping a close eye on Ana, as the storm was expected to make landfall there early Monday. It was packing winds of about 40 mph as it churned about 560 miles east-southeast of the islands. It was speeding west at about 20 mph.

Ana triggered a tropical storm watch for Puerto Rico, and watches remained in effect for the U.S. and British Virgin Islands, Montserrat, Antigua, Barbuda, St. Kitts, Nevis, Anguilla, St. Maarten, Saba and St. Eustatius. That means tropical storm conditions are possible within the next 36 hours.

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The Associated Press contributed to this report.