The first tropical storm of the season raked northern Florida with rain and powerful wind gusts Tuesday but didn't blow up into a hurricane as forecasters had feared.

A hurricane warning that had been issued for more than 100 miles of Florida's Gulf Coast was downgraded to a tropical storm warning before Alberto made landfall near Adams Beach, southeast of Tallahassee.

The storm's top sustained winds were 50 mph, well below the 74 mph threshold for a hurricane.

Click here to track Tropical Storm Alberto.

Click here to see the three-day storm prediction from the NOAA.

"The big concern now is going to be shifting to the rainfall and the tornado threat as it moves along the southeastern [U.S.] coast line," said National Hurricane Center director Max Mayfield.

A flood watch was issued for southeastern South Carolina, where more than 5 inches of rain was possible. Forecasters said parts of Florida and southeastern Georgia could get 4 to 10 inches of rain — welcome news to crews that have been battling wildfires for weeks in several parched Florida counties.

The storm's center came ashore around 12:30 p.m. about 50 miles southeast of Tallahassee, the National Hurricane Center said.

In nearby Steinhatchee, a small fishing town in the Big Bend, life already appeared to be returning to normal.

"The locals consider this a mosquito breeze," said Bruce Tayco, 33, who works at a restaurant. "When it's a tropical storm, we don't even consider it."

Alberto's wind and rain littered yards with tree limbs, tore off singles and flooded streets from Tampa Bay up to the Panhandle, but no major damage was immediately reported. A small construction barge hit the Howard Frankland Bridge in Tampa Bay, but not structural damage was reported.

Statewide, about 21,000 homes and businesses were without power.

Some streets were flooded near Crystal River, where residents gathered in calf-deep water and dropped sandbags in preparation for the afternoon high tide.

"We're trying to keep everybody from making waves," said Ron McNally, who stood outside his waterfront home urging passing motorists to slow down on the flooded street. "The water's right at the door. It can't take much more."

A wind gust of 60 mph was reported in Tampa before dawn, while a gust of about 50 mph was recorded to the north in Cedar Key, meteorologists said. Cedar Key City Commissioner Pat O'Neal said he was cautiously optimistic for the island village, but high tide there was also still a worry.

"We dodged a bullet," O'Neal said.

Even though Alberto wasn't expected to become a major storm — it wasn't until Monday, when it jumped from 50 mph to 70 mph in a three-hour period, that forecasters thought it might become a hurricane — Florida officials weren't taking any chances after last year's deadly hurricane season.

Gov. Jeb Bush signed a declaration of emergency allowing him to call up the National Guard and put laws against price gouging in place if necessary, and evacuation orders were posted for people in mobile homes or low-lying areas in at least five coastal counties including about 21,000 residents of Citrus, Levy and Taylor counties.

Homeowners gassed up their vehicles and stocked up on chain saws, plywood and other emergency supplies. Alberto also prevented the crew of space shuttle Discovery from flying Monday to the Kennedy Space Center from Houston for several days of dress rehearsals for their expected launch in July.

The tropical depression that produced Alberto formed Saturday, nine days after the June 1 start of the hurricane season. The storm's winds accelerated with startling speed Monday from 50 mph to 70 mph in just three hours. The minimum for a named storm is 39 mph.

Scientists say the 2006 season could produce as many as 16 named storms, six of them major hurricanes. Last year's hurricane season was the most destructive on record and the busiest in 154 years of storm tracking, with a record 28 named storms and a record 15 hurricanes.