Hurricane Ike gathered strength as it churned through the Gulf of Mexico's warm waters today on a track that would skirt the heart of the US offshore oil patch before hitting the Texas coast late tomorrow or early on Saturday.
Ike is a Category 2 storm with 100 miles per hour winds and could come ashore as a ferocious Category 4 storm on the five-step intensity scale with winds of 132 mph, the National Hurricane Center said.
But the latest projections pointed Ike toward the middle of the Texas coast, skirting to the west of the main region for offshore production in the Gulf, which provides a quarter of US oil and 15 per cent of its natural gas.
At 5am EDT (0900 GMT) today, the hurricane centre said in its latest advisory Ike was 620 miles east of Brownsville, Texas, and about 285 miles south-southeast of the mouth of the Mississippi River. It was moving west-northwest at 9 mph.
New Orleans, still scarred by Hurricane Katrina, which killed 1,500 people and caused $80bn in damage on the US Gulf Coast in 2005, appeared to be out of danger.
However, the centre early today extended a tropical storm warning as far east as the Mississippi-Alabama border, including New Orleans and Lake Pontchartrain. A hurricane watch remained in effect from Cameron, Louisiana west to Port Mansfield, Texas.
Texas officials ordered some residents in low-lying Matagorda and Brazoria counties to evacuate. Mandatory evacuations had been illegal in Texas but the state changed its laws after Hurricane Rita in 2005. So far evacuation totals are nowhere near the two million people who fled Louisiana coastal cities in the path of Hurricane Gustav.
Other residents were boarding up homes and businesses to prepare for hurricane-force winds that could arrive tomorrow.
"Right now, we have people coming in and out," said Steve Probert, who works at a hardware store in the resort community of Port Aransas, across the Laguna Madre from Corpus Christi. "They're buying everything we have under the sun."
President George Bush declared a federal emergency for Texas, allowing some federal disaster assistance.
Ike's current track would see it hit the Texas coast just north of Corpus Christi, a major Gulf Coast oil refining hub.
About 250 miles of Texas coastline from Matagorda Bay to Brownsville on the Mexico border are on alert for possible mandatory evacuations due to wide uncertainty over the storm's path. A line of buses made their way from Corpus Christi to inland shelters as the city evacuated some elderly and sick residents.
Some residents in Brazoria County south of the low-lying coastal city of Galveston were ordered to evacuate.
Texas Govenor Rick Perry said that some residents would likely resist evacuation calls but said he wants to see "buses, not body bags." Perry put 1,350 buses on standby to carry possible evacuees.
"We must have passed 50 or more people taking their boats and probably every mobile home in the state was on the road," said Margaret Romero, 67, who evacuated from Corpus Christi yesterday. "Our entire street - every house on our street was boarded up."
Torrential rains from the storm could be more damaging than its wind blasts, especially for heavily populated areas in the Rio Grand Valley which already took a soaking from Hurricane Dolly in July.
Ike could unleash up to four inches of rain on southern Louisiana, and produce storm surges up to five feet above normal tide levels, along with large and battering waves in some parts of the Gulf today, the centre forecast.
In Cuba, big waves and storm surges were expected to subside, but heavy rains on the island's western end could produce flash floods and mudslides, it said.
Ike has already caused widespread damage in Cuba.
Few official figures have emerged, but state-run media showed a panorama of destruction across the island, still reeling from the more powerful Hurricane Gustav 10 days ago.