Forecasters warned residents along the northern Gulf of Mexico coast to rush preparations Saturday ahead of an intensifying Hurricane Ida, which is expected to bring winds as high as 130 mph (209 kph), life-threatening storm surge and flooding rain when it slams ashore in Louisiana on Sunday.

Coastal highways saw heavy traffic as people moved to get out of the path of Ida, which the National Hurricane Center warned could grow to an extremely dangerous Category 4 storm. Trucks pulling saltwater fishing boats and campers streamed away from the coast Interstate 65 in south Alabama. Traffic jams clogged Interstate 10 heading out of New Orleans.

“We’re going to catch it head-on,” said Bebe McElroy, who was preparing to leave her home in the coastal Louisiana village of Cocodrie. “I’m just going around praying, saying, ‘Dear Lord, just watch over us.’”

A tropical depression two days earlier, Ida was strengthening so quickly that New Orleans officials said there was no time to organize a mandatory evacuation of the city’s 390,000 residents, a task that would require coordinating with the state and neighboring locales to turn highways into one-way routes away from the city.

New Orleans Mayor LaToya Cantrell called for a voluntary evacuation and reiterated Saturday that the time to safely leave was growing short. City officials also were preparing to open shelters for anyone displaced by the storm. They also warned those who stayed to be prepared for long power outages amid sweltering heat in the days ahead.

In Washington, President Joe Biden called Ida “very dangerous” and urged Americans “to pay attention and be prepared.” He spoke Saturday at the start of a virtual briefing with Federal Emergency Management Agency administrator Deanne Criswell on storm preparation.

Ida was poised to strike Louisiana 16 years to the day after Hurricane Katrina devastated the Mississippi and Louisiana coasts. The Category 3 storm caused levee breaches and catastrophic flooding in New Orleans, which took years to recover.

Ramsey Green, the city’s top infrastructure official, stressed that the levee and drainage systems protecting the city have been much improved since Katrina.

“That said, if we see 10 to 20 inches of rain over an abbreviated period of time, we will see flooding,” he said.

Lines at gas pumps and car rental agencies grew long as residents and tourists alike prepared to leave Saturday.

“We were willing to wait it out but the hotel said we had to leave,” said visitor Lays Lafaurie of Fort Worth, Texas, waiting in a rental car line at the city’s airport. “They said we had to leave by 7 tomorrow morning. But if we’d waited that long there wouldn’t have been any cars left.”

Ida posed a threat far beyond New Orleans. A hurricane warning was issued for nearly 200 miles (320 kilometers) of Louisiana’s coastline, from Intracoastal City south of Lafayette to the Mississippi state line. A tropical storm warning was extended to the Alabama-Florida line, and Mobile Bay in Alabama was under a storm surge watch.

Alabama Gov. Kay Ivey declared a state of emergency Saturday for the state’s coastal and western counties, warning Ida could bring flooding and tornadoes there.

Meteorologist Jeff Masters, who flew hurricane missions for the government and founded Weather Underground, said Ida is forecast to move through “the just absolute worst place for a hurricane.”

“”There’s hundreds of major industry sites there, I mean petrochemical sites, three of the 15 largest ports in America, a nuclear power plant,” Masters said. “You’re probably going to shut down the Mississippi River for barge traffic for multiple weeks.”

Phillips 66 said it was shutting operations at its refinery in Belle Chasse, Louisiana, based on Ida’s projected path.

Many gas stations in and around New Orleans were out of gas, and the few still open had lines more than a dozen cars deep.

Mike Laurent of Marrero, Louisiana, was filling up about a dozen gas canisters to fuel his generator and those of friends and family. Laurent said he and his family will be riding out the storm at home despite concerns about whether the nearby levee would hold. It was reinforced after Katrina in 2005.

“I don’t think it’s ever been tested like it’s going to be tested tomorrow or Monday,” Laurent said. “I bought a dozen life jackets, just in case.”

By midday Saturday, Ida was a Category 2 hurricane with maximum sustained winds of 100 mph 100 mph (155 kph). The storm was centered 380 miles (610 kilometers) southeast of coastal Houma, Louisiana, and was traveling northwest at 16 mph (26 kph).

In New Orleans, city officials said residents need to be prepared for prolonged power outages, and asked elderly residents to consider evacuating. Collin Arnold, the city’s emergency management director, said the city could be under high winds for about 10 hours.

Some ordinarily bustling businesses were closed Saturday. One popular breakfast spot was locked up tight with sandbags against the door to guard against flash floods.

Ida’s storm surge may overtop some coastal levees protecting parts of New Orleans on the west bank of the Mississippi River, said Heath Jones, emergency manager of the Army Corps of Engineers’ New Orleans District. However, he said they are designed to be overtopped and have protections in place to prevent more damage. He said there does not appear to be any danger of surge coming over levees protecting the city’s east bank, which makes up most of the city.

Cuba started to clean up Saturday after Ida tore through Isla de la Juventud and then western parts of the mainland. The storm toppled trees and damaged crops and buildings. There were no reported deaths.