KEY WEST, Fla. – Hurricane Rita (search) strengthened into a Category 2 storm with 100-mph winds on Tuesday as it grazed the Florida Keys. The islands were apparently spared the brunt of the tempest as the massive storm took aim at the Texas coast.
Authorities issued a mandatory evacuation order for Galveston County, Texas, which will take effect Wednesday, even though Rita most likely will not affect the region until the end of the week.
"This is a dangerous storm," acting FEMA Director R. David Paulison (search) said. "We don't know exactly where it's going to land. [Local residents] need to take it very seriously. Have your evacuation plan in place. Know where you're going to go and make sure you have your food and water supply for three days."
• Click here to track Hurricane Rita.
The National Hurricane Center (search) forecasts that Rita will become a Category 4 storm in the next 24 hours, FOX News has learned.
"Once the hurricane gets out in the Gulf of Mexico, we think it has the potential to be a major hurricane," Richard Knabb, a meteorologist with the National Hurricane Center, told FOX News.
Rita, whose storm surge could get up to 6 feet, is being watched carefully because forecasters are uncertain of its path. It's headed into the Gulf of Mexico and may veer toward the areas battered by Hurricane Katrina (search) three weeks ago.
Texas Gov. Rick Perry has asked President Bush to approve a disaster declaration for his state in anticipation of Rita. Bush has taken it under advisement.
Texas was in the process of evacuating thousands of Hurricane Katrina-weary refugees from shelters in Corpus Christi, Houston and Beaumont to other states.
Galveston is no stranger to deadly storms; the city lost between 6,000 and 12,000 people when a whopping hurricane hit Sept. 8, 1900.
Rita was upgraded from a tropical storm early Tuesday, reaching hurricane status with 100-mph winds by early afternoon as it passed just south of the Keys, the National Hurricane Center said.
At 1:15 p.m. EDT, forecasters at the National Hurricane Center said a hurricane hunter aircraft flying through Rita found it had intensified as the storm's center moved through the Florida Straits between Key West and Havana, Cuba.
Category 3 storms have maximum sustained wind of 130 mph; Katrina was a Category 4 hurricane when it hit the Gulf Coast with 145 mph sustained wind.
Thousands of residents and tourists have fled the Keys in advance of Rita, which forecasters said could dump up to 15 inches of rain on parts of the low-lying island chain.
Key West Mayor Jimmy Weekley said he was cautiously optimistic that the islands would be spared the full fury of the storm, with Rita's eye forecasted to remain at sea just to the south.
"I think we did, so far, dodge a bullet," Weekley said. "We still have some time to go."
Rita promised to continue gaining strength as it crossed the warm Gulf of Mexico for a weekend landfall, most likely in Texas although Louisiana or northern Mexico could also be targets.
"Right now, we expect that Rita will remain a Category 1 hurricane as it affects the Keys," said Chris Sisko, also a meteorologist at the National Hurricane Center. "Further out, we do anticipate further strengthening up to Category 3, or major hurricane status."
Florida Gov. Jeb Bush on Tuesday told those residents who have not yet evacuated to now stay put.
"If you haven't left the Keys already, stay where you are. This is not the time to evacuate … now is the time to hunker down," Gov. Bush said. "What we say around here is: Turn around, don't drown."
Bush also warned that even if the eye of the storm directly hit the Keys, strong winds could affect areas 120 miles out from the eye and heavy rains may cause flooding in other areas.
"It's important to remember … that a hurricane is not a point on the map or a skinny black line," he said. "This is a very serious storm that is about to hit our state."
About 1,300 people were being housed in shelters in Miami-Dade and Broward counties and all three Keys hospitals had been evacuated, Bush added.
Earlier Tuesday, officials in Galveston — nearly 900 miles from Key West — were already calling for a voluntary evacuation. The mayor advised residents to only bring one suitcase and three-months' worth of medication with them.
Louisiana Gov. Kathleen Blanco (search) urged everyone in the southwest part of her state to prepare to evacuate.
"If Rita passes us by, we will thank the Lord for our blessings," Blanco told the state's storm-weary residents in a televised address.
Hurricane warnings were posted for the Keys and Miami-Dade County, the National Hurricane Center said. Residents and visitors were ordered to clear out of the Keys, and voluntary evacuation orders were posted for some 134,000 Miami-Dade residents of coastal areas such as Miami Beach.
Along the Keys, seawater splashed across U.S. 1, the highway linking the islands, and wind hurled debris across roads. Streets were nearly deserted in Marathon, about 45 miles northeast of Key West, and virtually all businesses were closed, except for the Stuffed Pig diner, where workers promised to keep serving food regardless of the weather.
"We've stayed open lots of times with no power. We've got a gas stove, so it gets awful hot in here but we can still serve up food," said Julie Gervasio, who has worked at the restaurant for five years.
North of the Keys in Broward and Miami-Dade counties, more than 13,000 customers were without power. Most schools and government offices were closed.
The Florida National Guard expects to have as many as 1,600 guardsmen activated by the end the day in preparation for Hurricane Rita; 500 guardsmen are still on duty supporting Katrina in Mississippi. Florida has more than 8,000 Guard troops available in the state to respond to any emergency.
More than 200 truckloads of ice and water were prepared for delivery to the Keys if needed and helicopters are in place for search and rescue, he said.
"There will be a significant response," Gov. Bush said.
A spokeswoman for the Guard in Texas also said they're anticipating an activation order from the governor on Tuesday. About 2,100 National Guardsmen were in New Orleans for Katrina and are returning home on Tuesday. In addition, the state is moving 13 Apache helicopters from Houston to Austin to protect them from the storm.
Not everyone had fled the Keys.
Key West resident Linda McAlarney moved to temporary quarters at a local hotel and walked her dog, Onyx, just after daybreak Tuesday during a lull in the storm. Few others were out amid Key West's boarded-up shops and bars.
"I think evacuating is the right thing to do, and I probably should have done that," McAlarney said.
South Floridians kept a wary eye on Rita. The state has been battered by six hurricanes since August of last year.
"I've lived in Florida all my life," said James Swindell, 37, who shopped along a cleared-out Miami Beach on Monday. "You always have to be worried about a storm because they are too unpredictable and they can shift on you at the last minute. Nobody knows what they are going to do."
In New Orleans, Mayor Ray Nagin (search) suspended his plan to start bringing residents back to the city after forecasters warned that Rita could follow Hurricane Katrina's course into the Gulf of Mexico and shatter his city's already weakened levees.
"The levee systems are very wet, they're somewhat weakened, and any type of storm surge would cause flooding both in our parish and in other parishes. So we're not taking any chances," Nagin said.
Forecasters said 3 to 5 inches of rain was possible across southern Florida.
In the Bahamas, no serious damage was reported after Rita passed to the south. However, fishermen had dragged their boats to dry land and some people shuttered their windows — a sign that normally laid-back islanders were concerned.
"After what happened to New Orleans and the Gulf area, nobody is taking this storm lightly," said Ray Mackie, the owner of Tranquility Hill fishing lodge on Andros.
Rita is the 17th named storm of the Atlantic hurricane season, making this the fourth-busiest season since record keeping started in 1851. The record is 21 tropical storms in 1933.
The last hurricane to directly hit Key West was 1998's Hurricane Georges (search), which slammed the city with 105-mph winds, damaging hundreds of homes and closing the island to tourists for two weeks.
Rita brought new gyrations in the oil markets, including a $4-per-barrel increase Monday. Some companies, including Chevron and Shell, began evacuating employees from offshore oil and gas platforms. About 56 percent of the Gulf's oil production was already out of operation because of Katrina.
Elsewhere in the Atlantic, Hurricane Philippe (search) was far out at sea and posed no immediate threat to land. The hurricane season started June 1 and ends Nov. 30.
The Associated Press contributed to this report.
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