U.S. National Hurricane Center (NHC) warns Harvey is “rapidly intensifying” and creating a potential for “life-threatening and devastating” floods.

A large swath of the U.S. Gulf Coast hunkered down on Thursday as Hurricane Harvey barreled towards Texas and Louisiana — an area that processes some seven million barrels of oil a day.

The U.S. National Hurricane Center (NHC) warned that Harvey was “rapidly intensifying” and creating a potential for “life-threatening and devastating” floods.

The storm’s center was due to make landfall sometime early Saturday, with preceding strong winds arriving as early as 8 am (1300 GMT) Friday.

Harvey’s maximum sustained winds Thursday were about 85 miles (140 km) per hour, but the NHC said the category one hurricane could hit land as a much more powerful category three, with winds of 130 miles (209 kilometers) per hour.

If forecasts hold, Harvey would be the strongest hurricane to hit the U.S. mainland in 12 years.

“For anyone who has not already evacuated, please hurry to do so,” the city of Portland, Texas declared on its website in capital letters.

The storm was menacing one-third of the U.S. refining capacity, forcing several energy companies to take precautions and evacuate personnel from oil and gas platforms in the heart of the US “Refinery Row.”

One oil drilling rig in the Gulf of Mexico was evacuated Thursday, as well as 39 manned oil and natural gas production platforms, according to the Bureau of Safety and Environmental Enforcement.

Those evacuations represented an estimated 9.5 percent of oil production and 14.7 percent of natural gas production in the Gulf, the Bureau said.

Floods, storm surges expected

The storm was expected to dump as much as 35 inches (89 centimeters) of rain in some parts of Texas. Dangerous storm surges were also forecast to reach between six to 12 feet (1.8 to 3.7 meters) above ground level in the worst-hit regions.

Texas Governor Greg Abbott issued disaster declarations in 30 counties, saying the preemptive move would allow the State “to quickly deploy resources for the emergency response effort.”

Officials in Houston, the biggest city in the path of the storm, said they did not anticipate issuing evacuation orders, but expected heavy rainfall to last up to five days. City schools canceled classes through Monday.

“Houston will see close to 20 inches of rainfall,” officials said in a statement. “This is likely to cause dangerous flash flooding, and will cause area flooding throughout the entire Houston region.”

Corpus Christi — a major oil refining center where the hurricane was projected to make landfall Saturday morning — issued voluntary evacuation orders. The nearby coastal hamlets of Port Arkansas and Arkansas Pass both ordered mandatory evacuations.

A number of other municipalities in Texas also ordered evacuations.

Refining hub

US President Donald Trump weighed in with a tweet: “As #HurricaneHarvey intensifies - remember to #PlanAhead.”

In neighboring Louisiana where the storm was forecast to hover for many days and could deluge flood-prone New Orleans, Governor John Bel Edwards said he spoke with the president who “offered his full support.”

“This is going to play out over the next week or so,” Edwards told a news conference, “which makes it particularly dangerous... because the longer it sits in one place the more rain that it will drop.”

Edwards issued an emergency declaration for his entire state, as hundreds of boats were made ready for potential rescues along with more than half a million sandbags to hold back flood waters.

In New Orleans, where Hurricane Katrina in 2005 caused widespread flooding and killed more than 1,800 people, Mayor Mitch Landrieu told journalists that high-water rescue vehicles and boats were at the ready.

“We just need to make sure that we’re prepared for heavy rain over the course of the next week,” Landrieu said, adding that there were no evacuations planned.

This is the first major storm of the annual Atlantic hurricane season.

The Gulf region is only midway through the season, and has so far had eight storms that did not cause much concern, said Phil Klotzbach, an atmospheric scientist at Colorado State University.

“The tropical Atlantic remains warmer than normal,” Klotzbach told AFP, “so we are expecting an above-average overall season.”

According to analyst Phil Flynn of the Price Futures Group, the region in Harvey’s path is vital to the U.S. refining industry “running about seven million barrels a day.”

“Harvey’s greatest risk to refiners is not just wind damage to the refineries, but also the associated rainfall and the potential for electric power failure,” said James Williams of WTRG Economics.

Should a refinery shut down, he said it could take a week to get it up and running again.