Bands of rain from Tropical Storm Erin fell along Texas' coast early Thursday, while Hurricane Dean formed in the open Atlantic, becoming the first hurricane of the Atlantic season.

Click here to track Hurricane Dean.

Dean headed toward the Lesser Antilles in the Caribbean and could close in on the islands by Friday, forecasters said.

In flood-weary southern Texas, some vacationers packed up while others vowed to wait out Erin and its torrential rainfall.

The storm was not expected to gain hurricane strength before making landfall Thursday morning, which was why some said they wouldn't abandon long-planned trips to Texas' coast.

"It's not a hurricane. I ain't worried. If they say don't evacuate, I'm not going to worry about it," said Matt Sandlin of Amarillo, who was on a beach near Corpus Christi with his family on Wednesday as the wind whipped up and the horizon darkened with clouds. "Unless I see a shark or whale go flying by, I'm good."

Gov. Rick Perry ordered emergency vehicles and personnel, including National Guard troops, to the Harlingen and Corpus Christi areas.

"Because storms have saturated much of our state this summer, many communities in this storm's projected path are at high risk of dangerous flash flooding," Perry said in a statement.

Early Thursday, the National Weather Service issued flash flood warnings for six counties along the Texas coast near the anticipated landfall of the storm.

Cameron County Judge Carlos Cascos, the top elected official for the state's southernmost county, urged residents to evacuate trailers and mobile homes on South Padre Island.

Corpus Christi hadn't asked for any evacuations, said Ted Nelson, a city spokesman, and was keeping only a handful of people at the emergency operations center overnight.

"We're just advising folks to review their own personal emergency plans and look around your yard and remove any loose items," he said.

Nelson said that with 3 1/2 months left in the Atlantic hurricane season, the incoming storm was "a nice little wake-up call" for people to make sure they are prepared for more severe weather.

Some weren't taking any chances.

"We came out to get as much beach time in as possible," said John Cullison of the Dallas area, who was vacationing with his family and planned to leave southern Texas Thursday instead of Friday. "After the hurricanes from a few years ago, you have to take it kind of serious."

Erin formed late Tuesday as the fifth depression of the Atlantic hurricane season and was upgraded to a tropical storm Wednesday when its maximum sustained speed hit 40 mph. The threshold for tropical storm status is 39 mph.

At 5 a.m. EDT, the storm was centered about 55 miles southeast of Corpus Christi and about 180 miles southwest of Galveston, according to the National Hurricane Center in Miami. Its top wind speed remained at 40 mph.

Click here to visit the National Hurricane Center.

Erin was moving toward the west-northwest at around 12 mph and was expected to continue following that track for at least 24 hours.

The storm was likely too close to land to gain enough wind speed to become a hurricane, which would require sustained winds of at least 74 mph, said National Weather Service forecaster Tony Abbott in Brownsville. But the center said late Wednesday it could strengthen slightly before landfall.

Isolated tornadoes were possible along the middle Texas Gulf Coast on Thursday, the center said.

Forecasters at the National Hurricane Center in Miami said early Thursday they were beginning to see an eye form at Dean's center.

In the Caribbean, hurricane warnings were issued for the islands of Dominica and St. Lucia by their local governments as Hurricane Dean approached. Hurricane watches were in effect for the islands of Martinique and Guadeloupe and its dependencies, Saba and St. Eustaties.

Weather service of Barbados issued tropical storm warning for Barbados, and tropical storm watch for St. Vincent and St. Maarten. A warning means conditions expected within 24 hours, a watch means 36 hours.

At 5 a.m. EDT, Dean was centered about 485 miles east of Barbados and about 590 miles east of Martinique, according to the National Hurricane Center. It was moving west near 24 mph, and was expected to continue the same path for the next 24 hours.

Maximum sustained winds were near 75 mph, above the threshold for a hurricane. Dean is a Category 1 hurricane and is expected to strengthen during the next 24 hours, forecasters said.

Out in the Gulf, Shell Oil Co. evacuated 188 people from offshore facilities in the path of Tropical Storm Erin.

A tropical storm warning was posted for the Texas coast from San Luis Pass, about 50 miles southwest of Houston, southward to Port Mansfield, while the warning was canceled for the tip of the southern Texas coast. A tropical storm warning means that tropical storm conditions are expected within 24 hours. A tropical storm watch for northern Mexico was canceled.

Three to 8 inches of rain was possible along the middle Texas coast, the hurricane center said, with a storm surge of up to 3 feet above normal tide levels north of where the center makes landfall.

The U.S. Census Bureau said Wednesday that 4 million people could feel the storm's effects.

A series of storms this summer poured record rainfall across Texas and parts of Oklahoma and Kansas, with one July storm dropping 17 inches of rain in 24 hours. Flooding was widespread across all three states. It brought Texas out of drought status for the first time in more than a decade.

At least 16 deaths have been blamed on flooding since mid-June.

In the Pacific, Flossie was downgraded from a tropical storm to a tropical depression, a day after sideswiping Hawaii's Big Island with only intermittent rain and moderate winds.

Hurricane specialists expect this year's Atlantic hurricane season — June 1 to Nov. 30 — to be busier than average, with as many as 16 tropical storms, nine of them strengthening into hurricanes. Ten tropical storms developed in the Atlantic last year, but only two made landfall in the United States.