Hurricane Laura was expected to cause catastrophic damage and “unsurvivable storm surge” to the Gulf Coast near the Texas and Louisiana border after strengthening on Wednesday to a Category 4 storm, the National Hurricane Center said.

Laura, located 200 miles (320 km) south-southeast of Port Arthur, Texas, on Wednesday afternoon, had maximum sustained winds of 140 miles per hour (220 km per hour) and was expected to pack winds of up to 145 mph (233 kph) before landfall on Wednesday night, the Miami-based forecaster said.

Some 620,000 people were under mandatory evacuation orders in Louisiana and Texas.

The catastrophic storm surge could penetrate up to 30 miles (48 km) inland from the coastline between Sea Rim State Park, Texas, and Intracoastal City, Louisiana and could raise water levels as high as 20 feet (6 m) in parts of Cameron Parish, Louisiana, the NHC said.

“To think that there would be a wall of water over two stories high coming on shore is very difficult for most to conceive, but that is what is going to happen,” said National Weather Service meteorologist Benjamin Schott at a news conference. Most of Louisiana’s Cameron Parish would be underwater at some point, Schott added.

“The word ‘unsurvivable’ is not one that we like to use, and it’s one that I’ve never used before,” Schott said of the storm surge.

Temporary housing was being hastily erected outside the storm surge zone for evacuated residents, and emergency teams were being strategically positioned, state and federal emergency management agencies said.

Federal Emergency Management Agency (FEMA) Administrator Pete Gaynor posted pictures of portable shelters on Tuesday at Camp Beauregard, Louisiana, about 115 miles (185 km) north of the Gulf Coast.

Texas Governor Greg Abbott said his state’s National Guard was in place with high-water vehicles and rescue helicopters.

While Houston had earlier in the week feared Laura would deliver a direct hit to the fourth-largest U.S. city, the storm has shifted east and Houston, which was devastated by Hurricane Harvey in 2017, looked likely to escape the worst of it.

Louisiana Governor John Edwards said that the state’s entire National Guard had been activated for the first time since 2012. (Ernest Scheyder Gabriella Borter; editing by Jonathan Oatis and Marguerita Choy and Cynthia Osterman)

Topics Catastrophe Natural Disasters Texas Windstorm Louisiana Hurricane