STEINHATCHEE, Fla. -- A growing tropical depression in the Gulf of Mexico spawned heavy rain across Florida on Thursday, further dampening areas already soaked by one of the wettest summers in years.

As much as 15 inches of rain was expected during the weekend as the depression, likely to become a tropical storm, moves across the state toward the Atlantic Ocean.

"It's just raining. It hasn't kicked up yet," said Charles Norwood, an employee at the Sea Hag Marina at the mouth of the Steinhatchee River, about 125 miles north of Tampa. "I hope that's all we get -- wet."

The tropical depression was expected to build into Tropical Storm Henri by the time it hits the coast late today in the Cedar Key area and begins its slosh through the Florida Peninsula, forecasters said.

"But it's taking it's sweet time doing it," said Jack Beven, a hurricane specialist at the National Hurricane Center in Miami. The system's lingering in the gulf could lead to more rain in areas that don't need it, he added.

A tropical storm warning was issued for Florida's west coast from Englewood, south of Sarasota, north to the Aucilla River in the Panhandle, 20 miles southeast of Tallahassee.

Another 60 miles of coastline to the north was dropped from the warning late Thursday.

A tropical storm warning means that tropical storm conditions -- including wind speeds of at least 39 mph -- are expected within 24 hours.

At 8 p.m. EDT, the depression had maximum sustained winds near 35 mph. It was centered about 150 miles south-southwest of Apalachicola and was moving eastward at 7 mph, with a turn to the east-northeast expected by Friday evening, forecasters said.

Forecasters said the main concern was not wind but rain, unwelcome news in Florida cities that have had incessant summer downpours. The rainfall in Orlando and Tampa in August nearly doubled their historical averages for the month.

Thunderstorms on Florida's east coast were creating problems, as well. Up to 3 inches of rain fell on Orange, Osceola and Indian River counties during an hour-long span Thursday afternoon.

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On the Net:

National Hurricane Center: http://www.nhc.noaa.gov/