The Atlantic hurricane season gathered pace on Sunday as forecasters said Tropical Storm Claudette -- the third system to form in two days -- swirled off northwestern Florida, expected to dump heavy rains.
Ana, which just weakened from a tropical storm to a tropical depression, meanwhile raced toward the Caribbean, prompting storm watches from Puerto Rico to the Leeward Islands, while a slower-moving but potentially more menacing Tropical Storm Bill followed in the open Atlantic.
The trio had formed the season's first three named storm systems in the Atlantic. Forecasters said at least one of them, Bill, was expected to become a hurricane.
The US National Hurricane Center (NHC) said Claudette was gathering steam, with winds increasing to near 50 miles per hour (85 kilometers per hour), and expected to make landfall late Sunday near the northern Gulf Coast of Florida.
"There is the potential for some additional strengthening prior to landfall," the NHC cautioned, with rainfall of three to six inches (7.6 to 15.2 centimeters) expected in northwestern Florida, central and southern Alabama and southwestern Georgia. Up to 10 inches (25.4 cm) of rain was expected in isolated areas.
The storm was located about 40 miles (60 km) west-southwest of Apalachicola, Florida at 5:00 pm (2100 GMT), and about 120 miles (190 km) southeast of Pensacola, Florida, the NHC said.
More threatening was Bill, which strengthened in the open Atlantic and was to continue doing so through Tuesday, as the Miami-based Center warned it was "expected to become a hurricane later tonight or tomorrow."
Bill was still far from land, at about 1,440 miles (2,315 km) east of the Lesser Antilles. It was moving west-northwest at about 16 mph (26 kmh), with maximum sustained winds near 65 mph (100 kmh) and higher gusts.
Meanwhile, much further west, Ana weakened to a tropical depression, moving west at about 23 mph (37 kmh) at 170 miles (270 km) east of Dominica.
"On this track, the depression will cross the northern Leeward Islands tonight and enter the northeastern Caribbean Sea on Monday," the Center noted.
A tropical storm watch remained in effect for Puerto Rico, the US and British Virgin Islands, Montserrat, Antigua, Barbuda, St. Kitts, Nevis, Anguilla, St. Maarten, St. Martin, Saba, St. Eustatius, Guadeloupe and St. Barthelemy, it said.
In the Pacific, Hurricane Guillermo weakened and was about to cross into the Central Pacific, with its center located 995 miles (1,600 km) east of Hilo, Hawaii, moving west-northwest at about 14 mph (22 kmh), according to the NHC.
With winds having decreased to near 85 mph (140 kmh), it was forecast to weaken to a tropical storm by Monday.
A tropical storm becomes a hurricane when its winds reach at least 74 mph (119 kmh).
The Atlantic hurricane season began on June 1 and continues through November 30.