Thousands of tourists jammed a highway after they were told to evacuate the lower Florida Keys because Tropical Storm Rita developed over the Bahamas and moved toward the vulnerable, low-lying island chain.
A hurricane watch was posted Sunday for the entire Florida Keys, which means hurricane conditions of winds of at least 74 mph (119 kph)are possible by late Monday.
In Tallahassee, Gov. Jeb Bush declared a state of emergency for Florida, which gives the state authority to oversee evacuations and activate the National Guard, among other powers.
"It does look like that there is the potential for it to become a hurricane, near or just before it reaches the Florida Keys," said Daniel Brown, a meteorologist at the National Hurricane Center.
Long-term forecasts show the system heading generally toward the west in the Gulf of Mexico toward Texas or Mexico later in the week, but such forecasts are subject to large errors. That means that areas ravaged by Hurricane Katrina could potentially be in the storm's path.
"Once it reaches the Gulf, really everybody should pay attention at that point," Brown said.
As the storm strengthened hundreds of miles away, the lone highway in the Keys was packed with sport utility vehicles, RVs and motorcycles heading north to the mainland. The exodus caused a miles-long traffic jam in the two-lane section of U.S. 1 connecting Key Largo to Florida City.
Erik Juzman, 36, was among the evacuees when he stopped at a convenience store Sunday to take a break from the road.
"I take every storm seriously, so I always pack up and go," Juzman said. "Hurricane Andrew taught me this ... I'm not taking any chances."
Rita is the 17th named storm of the Atlantic hurricane season. That makes this season the fourth-busiest since record keeping began in 1851 21 tropical storms formed in 1933, 19 developed in 1995 and 1887 and 18 formed in 1969, according to the hurricane center.
At 8 p.m. EDT (0000 GMT), Rita had top sustained winds of about 50 mph ( 80 kph). It was centered about 330 miles (530 kilometers) east-southeast of Nassau, Bahamas, and about 580 miles (933 kilometers) east-southeast of Key West. It was moving to the northwest near 9 mph (14 kph).
Tropical storm force winds extended outward up to 70 miles (113 kilometers) from the storm's center.
Monroe County emergency management officials told visitors to leave islands extending from the Dry Tortugas west of Key West to the Seven Mile Bridge near Marathon. The islands are connected to each other and the mainland by a single highway.
Hundreds of motorcyclists were in the Keys for an annual event, but most were leaving Sunday, senior emergency management director Billy Wagner said.
County officials also urged residents of mobile homes to prepare for possible evacuation.
Michael Knowles, general manager of the Hampton Inn Resort in Key West, told his guests to leave Sunday but said he wasn't too worried about the latest weather system because it wasn't as strong as Katrina.
"These are like rehearsal drills for us," Knowles said. "I'm originally from the Bahamas so this is like my 25th hurricane."
Residents of South Florida and central and western Cuba also should closely monitor the system's progress, Brown said.
Katrina hit the Miami-Fort Lauderdale area last month as a Category 1 storm, killing 14 people and flooding some suburban and farming areas for days. The hurricane only caused minor damage in the Keys before destroying parts of Louisiana and Mississippi as a much stronger Category 4.
Hurricane Dennis brushed by the Keys in July, flooding some Key West streets, toppling trees and knocking out power. Dennis then struck a direct blow on the Florida Panhandle.
Katrina and Dennis were among six hurricanes to hit Florida in the last 13 months. Last year's four hurricanes killed dozens of people and caused $19 billion (€15.5 billion) in insured losses in Florida alone.
Peak storm activity typically occurs from the end of August through mid-September. The season began June 1 and ends Nov. 30.
Farther out in the Atlantic, Tropical Storm Philippe formed late Saturday well east of the Lesser Antilles. Philippe had maximum sustained winds near 50 mph, up 10 mph from Saturday. It was centered about 400 miles (644 kilometers) east of the Leeward Islands and was moving to the north-northwest near 8 mph (13 kph).