This satellite image released by the National Oceanic and Atmospheric Administration (NOAA) shows Hurricane Laura churning in the Gulf of Mexico, Wednesday, Aug. 26, 2020. Forecasters say Laura is rapidly intensifying and will become a "catastrophic" Category 4 hurricane before landfall. (NOAA via AP)

Hurricane Laura rapidly gained strength on Wednesday, forecast to become a "catastrophic" Category 4 hurricane before striking the Texas and Louisiana coasts with wind and water now swirling over much of the Gulf of Mexico.

Satellite images show Laura's remarkable intensification into "a formidable hurricane" that can smash homes and sink entire communities, "and there are no signs it will stop soon," the National Hurricane Center said.

"Some areas, when they wake up Thursday morning, they're not going to believe what happened," said Stacy Stewart, a senior hurricane specialist.

"We could see storm surge heights more than 15 feet in some areas," Stewart said. "What doesn't get blown down by the wind could easily get knocked down by the rising ocean waters pushing well inland."

Laura grew nearly 70% in power in just 24 hours to reach Category 3 status, with maximum sustained winds around 115 mph (185 kph) on Wednesday morning. It was about 280 miles (450 kilometers) out from Lake Charles, Louisiana, moving northwest at 15 mph (24 kph).

Top winds of 130 mph (209 kmh) are now predicted before landfall, pushing water onto more than 450 miles (724 kilometers) of coast from Texas to Mississippi.

"Heed the advice of your local authorities. If they tell you to go, go! Your life depends on it today," said Joel Cline, tropical program coordinator at the National Weather Service. "It's a serious day and you need to listen to them."

Cody Cloud takes a picture of the waves Wednesday, Aug. 26, 2020, in Galveston, Texas, as Hurricane Laura moves toward the Gulf Coast. Forecasters say Laura is rapidly intensifying and will become a "catastrophic" Category 4 hurricane before landfall. It's churning toward Texas and Louisiana, gathering wind and water that swirls over much of the Gulf of Mexico. (AP Photo/David J. Phillip)

Hurricane warnings were issued from San Luis Pass, Texas, to Intracoastal City, Louisiana, and reached inland for 200 miles (322 kilometers). Storm surge warnings were in effect from Freeport, Texas, to the mouth of the Mississippi River.

A Category 4 hurricane can cause damage so catastrophic that power outages may last for months in places, and wide areas could be uninhabitable for weeks or months, posing a new disaster relief challenge for a government already straining to deal with the coronavirus pandemic.

"We need to be concerned about the federal capacity to respond to a major hurricane disaster, particularly in light of failings that are all too obvious in the public health area," said Kathleen Tierney, former director of the Natural Hazards Center at the University of Colorado. "I really worry: Who's minding the store?"

A man walks along the beach Wednesday, Aug. 26, 2020, in Galveston, Texas, as Hurricane Laura moves toward the Gulf Coast. Forecasters say Laura is rapidly intensifying and will become a "catastrophic" Category 4 hurricane before landfall. It's churning toward Texas and Louisiana, gathering wind and water that swirls over much of the Gulf of Mexico. (AP Photo/David J. Phillip)

In the largest U.S. evacuation during this pandemic era, more than half a million people were ordered Tuesday to flee from their homes near the Texas-Louisiana state line, including the Texas cities of Beaumont, Galveston and Port Arthur, and the low-lying Calcasieu and Cameron parishes in southwestern Louisiana, where forecasters said storm surge topped by waves could submerge whole communities.

A National Weather Service meteorologist in Lake Charles, Louisiana—in the bullseye of Laura's projected path—took to Facebook Live to deliver an urgent warning for people living south of Interstate 10 in southwest Louisiana and southeast Texas. "Your life will be in immediate and grave danger beginning this evening if you do not evacuate," Donald Jones said.

Laura also is expected to quickly dump massive rainfall as it moves inland, causing widespread flash flooding in states far from the coast. Flash flood watches were issued for much of Arkansas, and forecasters said heavy rainfall could move to parts of Missouri, Tennessee and Kentucky late Friday, Laura is so powerful that it's expected to become a tropical storm again, menacing the northeastern United States, once it reaches the Atlantic Ocean.

Beachgoers sit on the beach Tuesday, Aug. 25, 2020, in Galveston, Texas, as Hurricane Laura heads toward the Gulf Coast. (AP Photo/David J. Phillip)

Urging people in southwest Louisiana to evacuate before it's too late, Louisiana Gov. John Bel Edwards said they need to reach wherever they intend to ride out the storm by noon Wednesday. In Galveston and Port Arthur, many people boarded buses to Austin and other inland cities.

"If you decide to stay, you're staying on your own," Port Arthur Mayor Thurman Bartie said.

Officials urged people to stay with relatives or in hotel rooms to avoid spreading the virus that causes COVID-19. Buses were stocked with protective equipment and disinfectant, and they would carry fewer passengers to keep people apart, Texas officials said.

Even before dawn Wednesday, officials in Austin said the city had run out of free hotel rooms to offer evacuees and had begun directing families fleeing the storm to a shelter nearly 200 miles farther north.

Owner Nick Gaido, top left, and Miguel Andrade secure a strap over a giant crab on the roof of Gaido's Seafood Restaurant, Tuesday, Aug. 25, 2020, in Galveston, Texas, as Hurricane Laura heads toward the Gulf Coast. The crab has been on display since 1960. (AP Photo/David J. Phillip)

"Everyone's recent memory is Harvey. We want them to evacuate," said Bryce Bencivengo, a spokesman for the Austin's homeland security and emergency management office.

Becky Clements, 56, evacuated from Lake Charles after hearing that it could suffer a direct hit, almost exactly 15 years after Hurricane Rita destroyed the city. She and her family found an AirBnb hundreds of miles inland.

"The devastation afterward in our town and that whole corner of the state was just awful," Clements said. "Whole communities were washed away, never to exist again. ... So knowing how devastating the storms are, there was no way we were going to stay for this."

Clements, a church educator, said she fears for her office, which is in a trailer following recent construction.

"I very much anticipate that my office will be gone when I get back. It will be scattered throughout that field."

  • John Prekosovich, left, and Joel Canales load a portable generator into A customer's vehicle at a Home Depot store as residents prepare for the possible landfall of Hurricane Laura, Tuesday, Aug. 25, 2020 in Houston. (Brett Coomer/Houston Chronicle via AP)

  • Gigi Hlavink purchases gas cans and other supplies at a Home Depot store while preparing for the possible landfall of Hurricane Laura on Tuesday, Aug. 25, 2020 in Houston. (Brett Coomer/Houston Chronicle via AP)

  • man, assistant operations manager, wheels a portable generator to the checkout stand for a customer at a Home Depot store as residents prepare for the possible landfall of Hurricane Laura on Tuesday, Aug. 25, 2020 in Houston. (Brett Coomer/Houston Chronicle via AP)

  • Houston SPCA staff members Linnea Wood, foreground, and Calista Stover carry pets from the Galveston Island Humane Society, onto a Wings of Rescue plane headed to Dallas/Fort Worth Tuesday, Aug. 25, 2020, in Houston, as Hurricane Laura threatens the Texas coast. (Steve Gonzales/Houston Chronicle via AP)

  • Municipal workers fill sandbags for the elderly and those with disabilities ahead of Hurricane Laura in Crowley, La., Tuesday, Aug. 25, 2020. (AP Photo/Gerald Herbert)

  • John Ray, top, boards up his house in Pirates Beach on the West End of Galveston with help from his friend Bryan Everett as Hurricane Laura tracks toward the upper Texas coast Tuesday, Aug. 25, 2020. (Jennifer Reynolds/The Galveston County Daily News via AP)

  • People wait in front of the Galveston Housing Authority offices to board charter busses that will evacuate them from Galveston Island to Austin in anticipation of impact from Hurricane Laura, Tuesday, Aug. 25, 2020, in Galveston. (Mark Mulligan/Houston Chronicle via AP)

  • Issac Alvarado, right, and Kevin Enriquez board up windows on coastal decor store Bayside Chic, Tuesday, Aug. 25, 2020, in Galveston, Texas, as Hurricane Laura heads toward the Gulf Coast. (AP Photo/David J. Phillip)

  • Evacuees board buses Tuesday, Aug. 25, 2020, in Galveston, Texas. The evacuees are being taken to Austin, Texas, as Hurricane Laura heads toward the Gulf Coast. (AP Photo/David J. Phillip)

The hurricane also threatens a center of the U.S. energy industry. The government said 84% of Gulf oil production and an estimated 61% of natural gas production were shut down. Nearly 300 platforms have been evacuated. Consumers are unlikely to see big price hikes however, because the pandemic has decimated demand for fuel.

Laura took aim at the U.S. after killing nearly two dozen people on the island of Hispaniola, including 20 in Haiti and three in the Dominican Republic, where it knocked out power and caused intense flooding. It's just days before the Aug. 29 anniversary of Hurricane Katrina, which breached the levees in New Orleans, flattened much of the Mississippi coast and killed as many as 1,800 people in 2005. Hurricane Rita struck southwest Louisiana weeks later as a Category 3 storm.