Sept. 11 (Bloomberg) -- Highways in Texas were jammed as coastal residents fled Hurricane Ike, which tripled in size in the central Gulf of Mexico and threatened the 5.6 million people of the Houston area.

The system's strongest winds extend as far as 115 miles (185 kilometers) from the eye, compared with 35 miles yesterday, the Miami-based National Hurricane Center said today. Ike's winds cover an area larger than that of Katrina, the storm that devastated New Orleans in 2005, Jeff Masters, director of meteorology at private forecaster Weather Underground Inc., said.

``The total amount of energy is more powerful than Katrina, so we could be seeing a storm surge that could rival Katrina,'' Masters said. Ike is so big ``the location doesn't matter much; it is going to inundate a huge part of the Texas coast.''

Galveston, parts of southern Houston and areas south of the city and near the Texas coast were under a mandatory evacuation order that started at noon today. Hurricane Ike is following a track similar to the 1900 Galveston hurricane that killed 8,000 people, the deadliest storm in U.S. history.

The storm is a Category 2 hurricane with sustained winds of 100 mph, up from 80 mph yesterday, the center said in an advisory at 7 p.m. Houston time.

Ike's center was 370 miles east-southeast of Galveston and moving west-northwest at 12 mph, with landfall south of Galveston forecast for early Sept. 13. Because of its size, Ike will be felt along the Texas coast long before landfall.

Packing Up

Three houses away from Galveston Bay in LaPorte, Jamie and April Ybarra packed their two children, two dogs and cat into a Chevy sports utility vehicle and prepared to leave.

``I think the call for evacuation came a little late,'' Jamie Ybarra, a 32-year-old safety coordinator, said. ``You hear the roads are crowded; you hear people are losing their cool.''

This is the third time the family has evacuated in three years, April Ybarra said. And ``we may not be coming back here for awhile.''

Ike's central pressure is more like that associated with a Category 3 or 4 storm, Masters said.

``It is a massive storm; it is impacting in terms of its scope 40 percent of the Gulf,'' said Michael Chertoff, U.S. secretary of Homeland Security, in a conference call from Washington. ``The most important message I can send is, do not take this storm lightly. This is not a storm to gamble with. It is large and powerful and carries a lot of water with it.''

The U.S. weather center's forecasters said Ike may strengthen to at least a major hurricane with Category 3 intensity, meaning sustained winds of at least 111 mph, before landfall. Other forecasters predict Ike may become a Category 4 storm, the second-strongest on the five-step Saffir-Simpson scale, packing winds from 131 to 155 mph.

Oil Fields

The storm is forecast to sweep through the center of the Gulf, missing the offshore Louisiana oil and natural gas fields. The Gulf is home to about a quarter of U.S. oil production.

Even so, about 96 percent of all oil production in the Gulf has been shut in along with 73.1 percent of natural gas plants, according to the Minerals Management Service, a bureau of the Interior Department. Some plants have been closed since Hurricane Gustav struck Louisiana last week.

Exxon Mobil Corp.'s Baytown facility, 17 miles east of Houston, is the country's biggest, with a capacity of 586,000 barrels a day. The Louisiana Offshore Oil Port, which is the largest U.S. oil-import terminal and handles 13 percent of imports, said it closed marine operations because of Ike.

Dow Chemical Co., the largest U.S. chemical maker, and competitors such as DuPont Co., LyondellBassell Industries and Texas Petrochemicals Inc. are closing plants in the Houston area. The Texas Gulf Coast produces two-thirds of the nation's ethylene, used in products from plastic bags to auto parts.

Declaring Emergency

President George W. Bush declared an emergency for Texas, his home state, and Governor Rick Perry readied 1,350 buses to evacuate residents in preparation for Ike's landfall. As many as 7,500 Texas National Guard members are on standby.

Houston's population is 2.2 million, making it the fourth- biggest U.S. city, according to the U.S. Census Bureau, and its metropolitan area, with a population of 5.6 million, is the sixth-largest in the U.S.

The Houston Texans pushed back their National Football League home-opener against the Baltimore Ravens by a day because of Hurricane Ike, while the Astros postponed two games ahead of the storm's arrival.

Officials in Harris, Brazoria, Chambers, Matagorda and Galveston counties ordered about 564,063 people to leave homes that are now in Ike's path. Television news reports showed miles-long traffic jams in the area.

`Follow Instructions'

``My message to Texans in the projected impact area is this: finish your preparations because Ike is dangerous and he's on his way,'' Perry said in a statement. ``If your local officials tell you to evacuate, follow their instructions.''

Ernest Baddeaux, a 66-year-old welder who lives a half- block from Galveston Bay in La Porte, said he wasn't going to heed the mandatory evacuation.

``The officials and media tell you to evacuate but they don't necessarily tell you where or how you're going to pay for it,'' he said as hammered plywood over his windows.

Baddeaux said he was reasonably confident his house, one of the few in the neighborhood raised on piers, would protect him. Hurricane Alicia, which hit the Houston area in 1983, brought a 12-foot storm surge that didn't reach his property.

``I think one other family on the street is staying, too,'' he said, adding that he has an electric generator, a gasoline supply and enough food and water to last for weeks.

Storm Surge

Jim Rouiller, a meteorologist with Planalytics Inc. in Wayne, Pennsylvania, said he's worried about storm surge damage around Galveston Bay, on the coast southeast of Houston, which may be in the top right quadrant of the storm field where rains and winds are most powerful.

Galveston's seawall is 17 feet high and the forecast storm surge is 20 feet high.

``If that's breached, a whole refinery complex goes under water,'' Rouiller said.

Some parts of the Texas-Louisiana coast may get as much as 15 inches of rain, the hurricane center said.

Ike could inflict between $5 billion and $15 billion of insured damage depending on how much it intensifies, said Steve Smith, atmospheric physicist for the Carvill reinsurance broker.

Union Pacific Corp. and Burlington Northern Santa Fe Corp., the two biggest U.S. railroads, halted some Texas trains in preparation for Ike, while Amtrak stopped passenger service in parts of Texas.

Operations in Houston and nearby Galveston were shutting down or already idled, Union Pacific and Burlington Northern said today. Kansas City Southern, the fifth-largest railroad, also suspended traffic headed for that region along the Gulf of Mexico.

NASA's Johnson Space Center heeded the evacuation order and prepared to shut its 1,600-acre base in Houston that houses Mission Control and the training ground for astronauts.

To contact the reporter on this story: Brian K. Sullivan in Boston at bsullivan10@bloomberg.net;

Last Updated: September 11, 2008 21:03 EDT