GALVESTON, Tex. (CBS NEWSPATH) — 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 (August 26) to a Category 4 storm, the National Hurricane Center said.

Gaido’s Seaside Inn in Galveston had windows boarded up and a sign that said, “First Virus Now This.”

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.

More than 420,000 Texas residents and another 200,000 people in neighboring Louisiana were under mandatory evacuation orders.

Crude oil production in the Gulf of Mexico has been paralyzed as companies batten down operations. Output cuts are nearing 90%, a level not seen since Hurricane Katrina in 2005.

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